How and why did I come to specialize in designing and building with Autoclaved Aerated Concrete (AAC)?

What is Autoclaved Aerated Concrete Designs(AAC)?

Autoclaved aerated concrete designs is made with completely inorganic, sustainable materials and there is no waste byproduct in its production. Unlike conventional formed concrete blocks (CMU) which is made with cement and course fine aggregate it is made with sand, lime a special kind of white clay and cement.

It is mixed with water in large square forms and aluminum oxide is added to the slurry and this causes a chemical reaction to occur. This reaction causes thousands of tiny hydrogen bubbles to rise in the mix and the slurry rises like yeast in bread dough. The result is millions of tiny air pockets are trapped in the concrete as it begins to cure. It is then placed in autoclaves to provide heat and pressure to cure it to its intended compression strength.

Though it requires a certain amount of energy in this process it is still less than half the energy that is consumed in the production of bricks and concrete blocks or even in kiln drying wood. When it is completely cured it is wire cut into dimensionally accurate blocks unlike CMU blocks which are not dimensional accurate and thus require being put together with thick bed mortar which can deteriorate and weaken the structure.

All the shavings from cutting the block are captured and used to make thinnest mortar for putting the blocks together and to also make lightweight stucco which is an ideal finish for the exterior or a lightweight plaster for the interior walls. In this process it is completely sustainable with no waste by-products since everything is recycled.

I became very fascinated with this product and yet skeptical as usual, and so I continued to research the product looking for performance reports. I read about a chemical factory in Germany made of Autoclaved Aerated Concrete Designs, which had a fire, and the fire was so intense the firefighters had to stand back and watch it burn for 4 days straight.

It was assumed that the exterior structure made of AAC was compromised so engineers checked it out and took core samples and it was as sound as the day it was completed even though the steel internal structure was vaporized. In 8 weeks, the factory was back in business.

I have seen what happens to CMU block structures when exposed to such intense heat. It just crumbles under this kind of stress.

I found another article and saw pictures of a house that survived a wildfire. The picture showed hundreds of slabs and basements all around except for this one house made of Autoclaved Aerated Concrete Designs and had a clay tile roof was the only thing still standing.

I also found an article and pictures of two Autoclaved Aerated Concrete Designs houses that were the only structures still standing after massive flood had swept all the other structures away.

Later I read about an Autoclaved Aerated Concrete Designs house in Indonesia that survived a class 4 cyclone. The pictured showed a vast expanse of vacant slabs and rubble and this one house standing unscathed. It had not only survived the high winds, but also the storm surge of water.

It is often the case that a house may survive the high winds of a hurricane/cyclone and even the objects that fly around and hit the structure during the storm, but when the seas recede, they finish off the houses already impacted. This Autoclaved Aerated Concrete Designs house had survived all these harsh elements that had destroyed all the other neighboring homes.

I was truly impressed and began to wonder if this material was available in the United States. I had read that one of the manufacturers, Hebel had plans for production of their Autoclaved Aerated Concrete Designs blocks in America and that they already had a factory in Monterey, Mexico and shipped their products worldwide.

I decided to make a call to Hebel in Germany to learn as much as I could. I learned they were building a manufacturing plant in Adel, Georgia, which is about a 4 ½ hour trip from Atlanta. I asked for all the literature they have on their products and asked the engineer who I was speaking to me to let me know when they would start production in Adel.

I learned all I could about building with Autoclaved Aerated Concrete Designs and decided I would design and build a house for my own family using this product. Twelve weeks later I got a call from the German engineer whom I had spoken with earlier.

He told me that he was in Adel, Georgia and they were starting production of their blocks. I made an appointment to meet him down there. In the meantime, I came up with at least a hundred questions I jotted down that I wanted to ask while I was there.

I took my house plans down with me and spent 2 ½ days there. I got a tour of the plant and watched a slurry being made and the chemical reaction when they introduced the aluminum to the mix. It was a marvel to behold, seeing the batch rise.

They had a two-day class for me to attend, which included building a small room with Hebel blocks and mortar.  This was a great hands-on experience, seeing how easy it was putting the blocks together and sawing the block with a basic hand saw.

I spent at least half a day going over my building plans and learning what alterations I needed to make and the reinforcement necessary to make this house a strong solid monolithic structure. I got a certification as a Hebel approved builder. I was convinced enough to make the investment of my time and financial resources to build my first AAC house for my own home for my family.

I had known even before I had finished my research that I would be building a house different and superior to conventional stick framed construction and that I would have to find a lot that stood alone outside a typical subdivision. I knew that my house would be appraised like all the other houses in such a subdivision.

We had found a 5-acrelot in an estate lot subdivision with lots of 2 ½ to 20 acres and all the lots had custom built homes. I had picked out a site on the lot and staked it out for grading with the front of the house to be facing solar south. I began designing the house for this site and it seemed like we went through endless revisions as my wife and I had differing visions of what we wanted for our floor plan.

I had decided to design and build our house out of Insulated Concrete Form construction, though I had still had certain misgivings about building the entire house out of this system. I still wanted to utilize this material for my basement even after I had discovered Autoclaved Aerated Concrete Designs.

I knew after seeing and working with AAC that it would not be suitable for a basement mostly below grade especially given our heavy red clay and the enormous hydraulic loads upon the foundation when the ground is saturated. Though AAC is a very strong system as compared to framed construction it is not as strong as poured concrete. However, especially now poured concrete is more expensive than Autoclaved Aerated Concrete Designs and AAC has a higher thermal mass relative to its width than ICF construction.

Unfortunately, I was not going to be able to get ICF forms from Georgia in time for our construction schedule. The closest forms were in Oregon, and I would have to wait for them to be shipped and pay that expense to use for our foundation. Also, I had a very good friend whom I have known for over 15 years who had been in the business of pouring concrete and waterproofing for longer than I can remember.

Since then, I became acquainted with a manufacturer/distributor for American Poly steel Forms here in Georgia and subsequently planned and built basements using their product and were pleased with the results.

I knew that my site would need a full basement where three sides would be mostly underground, and I planned to utilize the insulating value of the earth to make the basement a heat/cool closet to integrate into our heating cooling system. We formed and poured a steel reinforced monolithic slab installing vertical rods 16” on center for the subsequent reinforcement of the foundation walls.

We waited 28 days for the concrete to cure to its strongest strength which you can imagine is a very important thing to do when you are building an all-concrete house. Afterwards we poured a full surround 10” thick concrete wall and waited another 20 days before beginning Autoclaved Aerated Concrete Designs construction.

We set engineered wood web style floor joists for the first floor. I knew this was not the best option, since wood and concrete are not particularly compatible. If I had had a choice, I would have used 8” thick engineered floor panels from Hebel, but panels were not yet in production in Adel.

In fact, I received some of the very first blocks produced by the Hebel plant in Adel, Georgia. Since then, I have always specified in my plans the use of floor panels for floors and when possible, for roof panels.  In fact, they make panels up to 20’ long which can give you a clear span width up to 19’ 8” and as long as you want.

Our walls were built with standard 8”x 8” x 24” blocks which are the minimum for a load bearing wall. For residential construction they also make 8” x 12” x 24” blocks and for interior walls they have 4” and 6” blocks.  The blocks are less than 1/5 the weight of standard concrete blocks.

An 8”x8”x24” block weighs approximately 40 lbs.  Why are they so light?  It is because of the millions of small pockets of air trapped in the concrete in the chemical reaction process. This also is the reason for its high thermal mass and the reason it is fireproof. The blocks are 60-80% air.

It is approximately R-4 per inch of thickness. So an 8” thick block finished with light weight stucco and plaster has a thermal resistance of R-32. To give you a point of reference, a standard wood 2×4 stick framed wall with fiberglass insulation between the studs has a heat resistance of R-13.

To get anywhere near the same thermal resistance using stick framing you would have to use 2” x 8” studs and 1” of 2 lb density polystyrene double kraft faced aluminum thermal sheathing for the outside and 8” of fiberglass insulation between the studs

Especially now with the high cost of wood framing materials, thermal sheathing, and fiberglass insulation you would at least be spending 2 ½ times more than using Autoclaved Aerated Concrete designs.

Evenif you decided to build that way you will have created a new problem by making your structure so airtight.  You would be trapping in toxic vapors inside the house such as the gassing off off or maldehyde that is present in sheetrock, carpet and other building material such as OSB; and what about carbon monoxide from your gas fired furnace, gas water heater and gas stove?

A house needs to breathe especially in climates that have a high relative humidity. The fact that  Autoclaved Aerated Concrete Designs is porous, giving it its high thermal mass but it also allows the walls to release gases. Many people, including me are allergic to fiberglass insulation and it has been proven to cause many people to develop respiratory diseases over time.

You may have gathered earlier in my comments above that it is not a good idea to apply polystyrene foam thermal sheathing against a wood framed structure, because it traps condensation moisture between the foam sheathing and the wood frame, which for obvious reasons is not a good combination.

Furthermore, building primarily with wood is not sustainable. This is already the issue with non-regional lumber being used in climates that are not suitable. Here in the U.S we are already importing most of our lumber from places like Canada, Finland, and Norway to keep up with our demand for framing materials. Has it even occurred to you what kind of carbon footprint this is making on our planet?

If you are convinced that wood framing is your only option for construction for whatever reason, then use lumber that is grown, harvested, and milled in your state or at least in your region.

Now just a note here. Most of the stock plans found on my website are specified for primarily steel framed construction, because I know it is hard to find a builder that knows about any alternative construction method other than conventional framed construction and even fewer are willing to change or ask their crews to change to a new system.

Framing with light gauge steel construction is not much of a threshold of learning to overcome and many commercial framing crews do use light gauge steel construction. I have aimed in these plans to provide as high of thermal mass as possible using a standard 2×4 frame system and solid 2lb density foam thermal sheathing and sprayed in foam insulation between the studs.

This gives a thermal rating of R-22 as compared to the standard R-13. This type of application is completely appropriate for light gauge steel construction. I specify the roofs to be R-24- R-40. Well, you ask,’ is this not basically an airtight system?’ The answer is no because in every plan natural convection air flow is integrated into the over all heating and cooling system allowing the system to breathe

Furthermore, I integrate the use of Evacuated Tube Solar Thermal collectors(ETSTC) for domestic hot water and quiet and clean water source heating and cooling.

It was a challenge at first to find construction workers that were willing to learn how to build with AAC and this included skilled contractors in plumbing, electrical and HVAC. I promised these specialists that I would guide them through the whole process and pay them on a cost-plus basis since they had no idea how to estimate the cost of their application to the system.

I had the hardest time with the HVAC engineer. I calculated all the heating and cooling loads for him and confirmed these calculations through the Hebel engineers with whom I was working. For the size of 3040 square feet of conditioned space and our high cubic feet of air with our high ceilings and cathedral ceilings on the second floor that rose to 14 feet he was baffled with the load calculations I provided.

He specified a 3 -ton AC unit for each floor and I had to fight him to put in a single 3 ton unit for both floors.  Then I told him I wanted to use a very energy efficient heat pump water heater to provide endless domestic hot water and to run hot water coils inside the air handler to heat the house.

Since I was using the basement as a heat/cold closet drawing fresh air intake for the HVAC system from the basement which always stayed between 64-68 degrees this made the energy threshold to heat or cool very low.

I insisted on using the heat pump water heater for this purpose because the heat pump would dry the humid air out of the basement and not transfer humid air into the primary living space. He told me repeatedly that the initial cost of this system would never pay for itself and that I should use a gas fired furnace instead.

I had the good fortune of hiring a young Mexican man to help me with building the AAC walls. It took a while for us to get to understand one another since I knew very little Spanish and he equally so in English.

I worked with him and observed how he worked. I soon began to see he had an innate understanding of solid construction. One day I ask one of my Hispanic friends who is affluent in Spanish and English to come over so I could have a more in-depth conversation with my Mexican worker. I learned that in Mexico solid construction is more the norm than composition construction as in framed construction.

He said in fact he could not understand why gringos are so enamored with building our houses out of sticks and he especially could not get why we build our fireplaces out of wood. ‘That’s loco’, he said. I smiled and nodded. I learned that in Mexico he was a master mason, building with adobe, concrete blocks and had in fact worked on a house made of AAC.

I cannot tell you how thrilled I was. I asked him if he knew others that lived in the Atlanta area who had his experience. His grin was as wide as his face. “Si Tomas”. “I have 11 brothers and 3 sisters.”

Over the years I have employed some and all of them on my various projects and trained them through every stage of construction short of electrical and heating and air. They were invaluable to me and they became like family to me and I to them.

I heard in reading other posts that one of the biggest cons to AAC construction and for that matter solid construction in general is finding workers who know how to work with these materials. 

I have good news.

There are many Hispanic workers in the construction job market who have firsthand knowledge of solid construction and are easily taught how to work with AAC and not only are they easily taught but they are more than happy to learn.

If you find a builder who is willing to build your plans out of ICF and AAC, I have more than 20 years of hands-on experience designing and building with these forms of solid construction and can certainly train a crew and advise specialty contractors in doing their work on these kinds of structures. All our plans can be altered to be constructed with Autoclaved Aerated Concrete design.

While I was building my house in Canton, Georgia one of my soon to be neighbors came to visit our jobsite. He also was a builder and was constructing his own house for his family’s home in eyesight of my home. He was building a stick framed house with “real” cement-based stucco siding.

“What the hell are you building here, a fortress?” I stopped to chat with him a bit and shared briefly what we were building. His response was basically: this is going to cost you a fortune and is completely unnecessary.

Like a trout rises to a fly, I bit. I said, “I tell you what, I will share with you my utility bills for you to examine if you will show me yours.” He responded immediately, “You’re on.” I smiled and nodded. His house was slightly bigger than mine, but I figured when it came down to total cubic feet of air to heat and cool they were nearly identical. We exchanged utility bills for about 6 months. My bills were less than a third of his, both in summer and winter.

I made note after that of crews coming and going from his house doing repairs. In the 20 years we lived there he had to have large sections of his stucco siding torn off and the OSB sub wall removed, and the stucco replaced. I know that this was at least 4 times.

When a severe storm came through with high sustained winds and hail the size of baseballs, all my neighbors had to have their roofs replaced and even sections of siding, but our architectural standing metal roof and house went unscathed.

We had no maintenance to do on our house other than now and then pressure washing the walls. Even when a tree fell in our back yard hitting our house the only damage that was done was a corner of our back porch roof had to be replaced and a small chunk of block was broken out which I easily repaired using color integrated lightweight stucco I had left over from building the house. Other than that, there was no damage to our structure.  The tree that fell was no small tree.

I may not have mentioned it earlier but what makes AAC so strong and resilient is that when built according to engineering standards for this type of material it is a monolithic structure unlike other concrete block structures. The weak part of other masonry block structures is that the weakest part of the wall is the sand and cement based mortar joints which decay over time and when impacted like in being hit by a tree the wall gives way mostly at the joints.

Also, as in poured concrete, which is very strong, it is also very rigid and when there is a significant impact that impact is transferred through the entire system and cracks occur, which are in some cases impossible to repair.

What Makes AAC Different?

The difference is that AAC blocks are dimensionally accurate, so they do not need to be put together with thick bed mortar. Instead, they are put together with thin set mortar made from recycled byproduct of the production of the blocks.

When this mortar is applied it literally sucks the blocks together and this bond cannot be broken no matter what you do. These joints are 1/16-1/8” thick. Also because of the nature of the blocks they tend to absorb the impact rather than transferring this impact through the whole system.

I know firsthand that this is true. Several years ago, I was called upon to inspect an AAC house that went through a tornado. A 6” diameter tree branch impelled one of the walls and knocked out about a 16” chunk out of the wall.  This kind of impact would have brought down a stick framed wall. I carefully checked throughout the entire wall and all the exterior walls, especially the corners and there was no damage.

To repair this wall all I had to do is drill four-1” diameter holes with a spade bit just below the top bond beam and down below where this chunk of concrete was knocked out. Then with a 12” long reciprocating saw blade in a reciprocating saw, I cut a nice true square out of the wall.

After this it was a matter of installing new AAC blocks and finishing it out by replacing the color integrated lightweight stucco of the original to match the existing wall. The lightweight stucco is also made from recycled AAC shavings from cutting blocks in production. This is a perfect monolithic bond to the block because it is the same as the block.

After living in this house for a year I had observed that there was never more than a 6-degreetransfer in temperature over a 12-hourperiod of time even on the hottest days of summer or the coldest days of winter.

So, I programmed our thermostat to only come on after 11:00 at night. Our electric provider drops its rates during this period. Our living environment was never uncomfortable.

When our electricity went out, we would set a fire in our controlled draft, catalytic low emission woodstove insert. This heated the whole house and after a while I needed to open a window upstairs to draft out some of the heat.

The other thing we noticed while living in this house was how quiet it is. We could not hear when the air handler turned on. We also could not hear when delivery trucks or service trucks came and sometimes, we could not hear our four watch dogs who always announced the arrival of any visitors.

If you were planning on visiting us, you needed to call ahead of time. Autoclaved Aerated Concrete Designs makes for a quiet house because it has such great sound isolating properties. I know of a sound recording studio on a college campus that is built not much more than 30’ from an active train track that is built with 12” thick Autoclaved Aerated Concrete Designs block and 12” thick floor panels. The noise of the train never interrupts their sound recording.

The other thing we noticed living in the house over 20 years was we never saw insects of any kind inside our house.

So to summarize why I chose to specialize in designing and building with Autoclaved Aerated Concrete designs Houses:

1. It truly is a sustainable building material and because of its high thermal mass making it highly energy efficient and because of this it makes sense to pay the higher initial cost of designing and implementing alternative sustainable renewable energy systems.
2. It has proven itself as a very durable and reliable material in widely diverse climates all over the world now for 100 years.
3. It is a very low maintenance house.
4. It will not rot or otherwise deteriorate.
5. It is fireproof. Its official 4 hour fire rating is for sustained temperatures of 2000 degrees.
6. It is completely insect proof.
7. It is highly resistant to severe conditions such as high winds, floods and even earthquakes.
8. It is moisture resistant and cannot grow molds or other organisms like organic building materials.
9. It is a breathable material and puts off no VOC and that makes for a healthy house.
10. It is a user-friendly material that can be cut, drilled, and shaped with regular woodworking tools and can even take course threaded screws or cut nails.
11. Because of its high sound isolation properties, it makes for a quiet house shutting out noise pollution.
12. There is no organic or inert waste at the end of construction.

I have read and heard of the so-called cons of building with Autoclaved Aerated Concrete Designs as compared to building a wood stick framed house, which is like the futile exercise of trying to compare apples to oranges or ants to elephants.

They are not the same. The question I get most often is it more expensive than 2×4 wood framed construction?  Remember you are talking about a wall at best is R-13 compared to a standard 8” AAC wall which is R-30.

The answer is that it is more expensive. After having designed and worked hands on with this material for over 20 years I can tell you that the cost difference averages about 15% more than a standard 2×4 framed wall system. However, having recently looked at the inflated price for wood framing materials and the latest price list of Autoclaved Aerated Concrete Designs materials this difference is probably closer to 8%.

If you are really serious about sustainability and your own personal impact on our environment then, you should really give designing and building with AAC serious consideration.

The other serious consideration you should take into account is not about initial costs but lifetime costs in energy bills and maintenance. I know from having lived in an AAC house for 20 years that this cost savings more than pays for the initial price.

If you are interested in building with ICF and Autoclaved Aerated Concrete Designs I suggest you look through our current stock plans and there will be many more to be posted. If you see a floor plan you like we would be pleased to alter it to be built with these materials.

We also are happy to work with you in designing a custom plan for your lot and providing consultation to you and your builder.

In case you are wondering if Autoclaved Aerated Concrete designs is available in the United States here is a list:

Hebel’s primary manufacturing Plant in North America is in Nuevo Leon, Mexico and its primary distribution center in the United States is in San Antoinio, Texas with other distribution centersin Chicago, New Mexico, Texas, Wyoming, and Oregon.

Megacrete a completely owned and operated American company has centers in: Monterrey, Mexico, Bennettsville, SC, Haines City, Fla, and Kerrville, Texas.

I am the most acquainted with Aercon in Haines City, Florida.

My first Autoclaved Aerated Concrete Designs House and our home for 20 years. Completed in 1996 in Canton, Georgia

This is our Autoclaved Aerated Concrete Designs house under construction. The gable ends are being constructed. This is the front face of the house.

This is an AAC house we are putting in roof end corbels for the installation of Autoclaved Aerated Concrete Designs Roof Panels.

We cut our own U-blocks for window and door lintels and top of the wall bond beams. These U-blocks serve as permanent forms. After being installed rebar reinforcement will be placed inside ready to be filled with 4000 psi grout that we will make and pour on site.

This shows the use of U-blocks for a wide opening in the wall and the rebar placed for reinforcement. This is the center of the house where the stairwell is to be placed and these walls will extend to the top of the clerestory which is the highest point in the house.

The green pipes you see are 6” diameter pipes that will extend to the top of the clerestory. These are part of 160’ of pipe loop buried an average of 8’ underground which provide a continuous flow of air averaging 62-66 degrees all year round and this ground cooled air is drawn through the house by way of the clerestory through natural convection air flow as well as fresh air intake on the central air handler.

This shows the stacks of floor panels which are being lifted by a crane to be placed at the top of the first-floor walls.

Here we are setting the factory engineered with integral reinforcement floor panels in place. These are 8″ thick floor panels.

This mountain house has four floors.  The two bottom floors at the front is mostly underground. These two lower floors are 12′ tall and were made with permanent Insulated Concrete Forms (ICF) which are American Polyester Forms. The top two stories above grade are built with Autoclaved Aerated Concrete Designs.  All the floors have factory reinforced Autoclaved Aerated Concrete Designs floor panels.

Autoclaved Aerated Concrete Designs is a very user-friendly material which can be cut, shaped, and drilled with basic woodworking tools. This picture shows fluted and chamfered corner quoins and basic window details all of which were shaped by a router on site and installed.

These elements have been finished using color integrated lightweight stucco, which is made from recycled by-products of the manufacturing process. If you look closely the walls are plastered with a pale-yellow stucco and the detail elements are finished white with a fine sand finish.

Autoclaved Aerated Concrete Designs I feel I need to give a thumbnail sketch about my construction background to explain how and why I came to specialize in designing and building with Autoclaved Aerated Concrete Designs (AAC). I started in construction when I was 14 years old working for one of the finest master builders in the Atlanta Metro area. We built high end houses. The builder gave me the opportunity to work on the various crews from framing, plumbing, electrical to finish carpentry. I learned what all goes into building a house.

The next five years in the summers, after school and on weekends I worked for a millwork company making cabinets, custom furniture, doors, moldings, and other millwork. We took on a project working to restore an old farmhouse built before the American Civil War.

It was built in the Empire style of architecture. We worked on repairing and/or replacing cornices, railings, balustrades windows and doors. Many of the windows and doors were beyond repair so we carefully salvaged the wavy poured glass and made new windows and doors exactly like the original fixtures installing the original glass.  We also restored the leaded etched and beveled glass for the great front entrance, which included repairing and replacing the lead glazing.

Furthermore, I learned from an old paint restoration specialist how to make restoration paint to be as exact as possible to the original paint that had preserved the exterior of this house for over a hundred years. I marveled at the details that went into the work of building this grand house and of all the craftspeople who produced all its elements with the materials they had available to them on the building site with only hand tools, most of which were produced by the artisans themselves.

This project took us with power tools more than 6 months to complete. I can only image what it took for the original craftspeople to construct this house. I gained an enormous appreciation for fine craftsmanship and their love of their trade. I began to learn what craftsmanship, materials and building practices go into building a house that last for centuries and serves the dwelling needs of many generations.

Another summer while in college I worked with an antique restoration specialist restoring fine antique furniture. He introduced me to epoxies for permanently bonding together joints and especially in chairs.

More than this I learned how to reproduce intricate details using casting rubber and filling those molds with color integrated epoxies to reproduce elements that were missing on pieces we were restoring. Many of the pieces we got to restore were little more than a pile of lumber.

To restore such pieces, we had to be well versed in the styles and techniques of the original periods when these pieces were produced. Through this work in reproducing intricate elements, we got a job working on a Victorian house in which many of the original plaster moldings had disintegrated.

This often happens when central air and heat are installed in an old house which dries out the old horsehair plaster moldings. We were able to produce rubber molds from the surviving original plaster cast moldings and permanently make exact reproductions out of epoxy and install them into the places where the originals had deteriorated.

While in graduate school I worked on the carpentry crew specializing in repairing or replacing cornices, corbels, windows, and doors on the old buildings on campus. Later I started my own antique restoration business working on all kinds of fine antiquities from 1000-year-oldGrecian urns to Chinese Chippendale sofas and chairs.

One of my clients had spent years traveling around the world purchasing precious antiques and shipping them to her two historical mansions in the United States. I spent a great deal of my time working on these pieces.  She introduced me to one of her friends who was an interior designer for the finest historical mansions in Louisville, Kentucky, which she furnished in antiques and exact antique reproductions. Among the projects I did for her included producing exact period reproductions.

Through these relationships I was asked to work as a consultant on the restoration of the Governor’s Mansion in Frankfort, Kentucky. My work included acquiring antiques throughout Kentucky and restoring these period pieces to furnish the mansion. I also served as an adviser on how to restore the building itself.

I have carefully observed many antique buildings to especially understand what materials, craftsmanship and techniques the original designers and builders employed with the resources available to them to make these structures durable and reliable for the many generations who have dwelled in them.

I have seen what works and does not work over a long period of time. What has impressed me the most is how they have employed simple principles of thermal dynamics to make these homes comfortable homes for their occupants. I have observed in many old houses built especially in the South with hot humid summers turn the house to the prevailing breezes and have a large central hall through the width of the house with high ceilings where they would spend their summer days enjoying the constant cross through breezes.

I have observed houses that have utilized the simple principle of convection air flow using tunnels or thick stone earth bermed cellars as heat/cold closets and cupolas at the apex of the house to create a natural convection air flow drawing the cool air from these tunnels or cellars through the house to both heat and cool the houses.

Other houses as early as the mid-18th century have used solar thermal collectors to provide hot water and heating the house by placing lead or copper pipes on the roof with a fire in the basement and iron radiators throughout the house to heat the house in the winter. They used the principles of thermal dynamics and the direct energy of the sun. These systems used a closed loop of tubes filled with water to heat to a certain temperature and the hot water rises back to the top of the system and flows throughout the series of cast iron radiators.

One such house was in upstate Western New York just below the St. Lawrence Seaway where the winters can be quite harsh and some of the summer days just the same. This estate was built around 1730. This house was built out of thatched hay between hewn logs for the structure and the joints plastered on both sides. This created a high thermal mass to keep heat in and prevent hot summer heat from radiating through the walls.

Later, the outside of the house was sided with clap board and porches were built around the perimeter of the house to both protect the windows and doors and utilize passive solar energy on the south face where most of the windows were placed. The original roof was made with thatched water grasses and later probably in the early 19^th century a zinc standing seam metal roof was installed on which the solar collectors were placed.

Probably about the same time two cupolas were placed at the top of the roof. These cupolas had light weight louvers made of zinc which would remain closed until the temperature reached approximately 96 degrees. The thermal pressure would cause the louvers to slightly open and create a draft which would draw the cool air out of the basement and vent out the hot air at the top of the building.

The basement was deep, approximately 12’ and the walls were made of thick stone collected from the property and was covered with earth on all sides except a small section where there was a large walk-out door.

During the winter they cut slabs of ice from the near by lake and stored them in the basement insulating the slabs with hay. This would last them through the summer, fall and spring. Needless to say, this greatly improved the cooling effect in the house throughout the summer. This house remains between 58-68 degrees throughout the year no matter what the winter or summer extremes may be.

This is just one example of many I could share where the designer/builder’s resourcefulness and understanding their environment and the simple principles of thermal dynamics was employed to make their houses as comfortable a home as possible for its inhabitants over many generations.

The simple principles they employed:

1. Prevailing breezes.
2. Passive and direct solar energy.
3. Hot air or water rises and cool air or water falls.
4. The constant cycle of convection air flow.
5. High thermal mass slows the transfer of hot or cool air.

These principles, though simple, always work. In our modern age of advanced technology and automation there is, it seems, a certain kind of arrogance and ignorance of the things that have proven reliable for centuries. I for one choose not to be arrogant or ignorant in designing and building houses that will prove reliable, durable, and highly energy efficiency to serve the dwelling needs of many generations.

So for me the simple principles I have enumerated above are of first course of action in my designing process. That does not mean that I do not keep abreast of latest technology or of the current resources available to utilize in my plans, but for me first course is to be observant of the resources available on the site and to work with the sun rather than against it and to intentionally work as much as possible in a synergistic relationship with the environment.

In 1990 I returned to Atlanta, Georgia which is my home. I started out repairing and replacing outside wooden decks and creating a formula to preserve them from the effects of the sun and weather. This led to repairing rotten door frames, windows sills and other exterior elements on houses.

My aim was to provide as much as possible permanent solutions to my client’s house maintenance issues. I utilized my knowledge of epoxies to repair many of the more minor deterioration issues and built porches to cover entrances and soffits and gutters to repair and prevent damage to bay windows.

I also utilized polyurethane moldings and as Poly Vinyl Carbonate(PVC) building materials became available in sheets, I built windows and door frames with these materials as permanent solutions. I have been in the business long enough to have seen almost all the materials that construction manufacturers have made grand promises as to their usability and durability all fail miserably and costing homeowners small fortunes in costly repairs.

Admittedly many of these failures were a result of improper use and poor workmanship, but nonetheless these manufacturers over promised their products and in the end the cost was absorbed by unwitting homeowners. A couple of products among numerous others were hardboard (same as the material used to make cardboard so I often refer to it as cardboard siding) siding and Overlaid Strand Board (OSB) siding.

Here in the Southern United States one of the most disastrous building materials was the use of Exterior Insulated Finishing System (EIFS). This is a system where 1-3” of 2 lb. density polystyrene foam is applied to the outside of a framed structure and is finished using synthetic stucco made of plastics.

Sounds like a good idea, right? 2 lb. density polystyrene foam has a heat resistance rating of R-4 per inch of thickness, which is a great thermal mass where 2” of this sheathing is R-8 and this added to 4” of fiberglass insulation between the 2×4 studs makes for a R-21 wall. It seemed like this was a good way to improve the energy efficiency of a standard framed wall.

This system works just fine in climates where the relative humidity is low, but in the South where the relative humidity is high throughout the year this system proved to be disastrous.

This is because this system developed an airtight envelope as well as a watertight envelope. The results were that condensation moisture got trapped between the EFIS and wood frame walls and had no place to go causing rot, black mold, and insect infestation in the wood structure.

Here, especially in the South, a house needs to have breathability to allow moisture and other vapors to escape. What exacerbated this problem with EFIS coatings over wood is that our framing materials come from other regions whose climate is significantly different.

Most of our wood framing materials come from the Northwest, Canada, Finland and Norway where the relative humidity is low. This timber is much lower density and porous than Southern Yellow Pine and thus cannot tolerate the moisture we always have in this region, so it is subject to rot, molds and insect infestation. Furthermore, trees have a natural adaptation to its environment and the indigenous insects.

To give you an example, I worked on restoring a church building that was built just after the American Revolution in Kentucky. I am sure that when they built the building it was outside the flood zone of the nearby river, but over the years the seasonal floods gradually encroached upon this building and now the building was flooded every spring. This had washed out the stack stone piers the building’s structural timbers rested upon. Now these beams were mostly sitting in mud.

We had assumed that we were likely going to have to replace these beams, because of rot and termite damage. I had asked the local craftspeople 6 months before we had scheduled restoration of this church building to cut down local pine trees 20” in diameter and larger to be prepared to start drying out so we could bring in a mobile sawmill to cut lumber we would need to restore this building.

The task before us was to jack this building up high enough to get it above the flood level and replace and salvage the stone from these piers with cast concrete and then used the salvaged stone to cover the piers. The timbers under this building were enormous and ran the entire length of the building.

They, no doubt were cut from the nearby virgin forest. To my surprise these timbers were mostly sound. The only damage was to the outside sap edge of these virgin pine timbers where rot and termites had tunneled but had not touched the heart wood at the core. So all we had to do was strip off this outside layer of these beams.

I have not seen any of these EFIS sided buildings over wood frame in my region of the South that were not subject to rot, mold, and termites. I cannot tell how many of these houses I have stripped all the EFIS siding and replaced destroyed wall, floor and even roof structure piece by piece.

You can only imagine what that cost the homeowners. I got so when I came to inspect these houses I went first up to the attic to see if termites had encroached up to this space and in many cases found them. I always told the owners in this case that it was in their best interest to have their house pulled down with an excavator and hauled off, because the cost of restoring their house was way more than building a new house.

I have even seen EFIS walls installed on wood frame below grade. These ghastly misapplications of this product has cost homeowners millions of dollars which they will never recover.

I fault building material scientists for this misjudgment. Just because a product may perform well in one region does not mean it is appropriate in others. This short-sightedness continues and building material manufacturers continue to make high promises of their material’s durability, reliability, and suitability for use everywhere.

The demand for wood framing materials greatly exceeds the availability of the supply of locally grown timber.

I have seen this same mentality with Leadership in Energy and Environmental Design(LEED) which is the official measure of so called leading “green construction”. I personally give little credence to their certification.

I in fact have come back behind these LEED certified builders to repair and replace materials and workmanship that has failed and costing homeowners dearly. This systematic ignorance of regional differences serves the material manufacturers and their products more than the homeowners who will live with the short-sighted results.

I know we have filled landfills with these sidings and the resultant deterioration of these wood structures.

After synthetic stucco failed, then many builders decided to use “real” stucco directly over Overlaid Stran Board (OSB) and called this “green construction” because they are using recycled wood in OSB. Masonry stucco has been used as a classical finish for centuries but was never intended to be used over stick frame construction but for over solid inert structures such as concrete, brick or stone.

Wood is an organic material and is in constant flux depending upon its environment. This expansion and contraction cause cracks in cement stucco over a wood frame and subsequently moisture incursion. Cement based stucco is not waterproof nor should it be because especially here the structure needs breathability. Synthetic or “real” stucco are not suitable for a wood framed structure especially here in the South.

The largest infestation of black mold I have ever seen is under this masonry-based stucco where the food for this mold has been the delaminating OSB subbase for this stucco.

Now every house and building is covered from sub walls, roof decking to subfloors and even as the backing of laminate flooring with OSB and then covered with plastic wrap. To say the least this traps the innate formaldehyde this product to preserve it.

This is a toxic environment for an indeterminate amount of time. I have asthma and when I enter one of these new “green” structures I begin to experience wheezing and shortness of breath.

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We have done many bathroom remodels and invariably when gutting out the existing showers we have found rotted out subfloors and often floor joists and in some cases side wall structure. In two cases the existing shower had fallen through to the first floor necessitating the homeowner to have to remodel their bathrooms.

Besides finding rotting wood structure I almost always found faulty plumbing and wiring. In one house that was just 4 years old I found when tearing out the shower walls that one Pex pipe connection had never been cinched and had been leaking since day one. It was a part that then only cost $.75 yet the restoration and remolding cost the homeowners thousands of dollars.

At least a dozen times I have found live electrical wires just hanging in the walls without being housed in a box or capped with wire nuts. I do not have to say how dangerous that is. In two cases these live wires were in a metal electrical box uncapped.

We have also done numerous kitchen remodels, building the cabinets on site to make them an exact fit for the space and maximizing cabinet space. The same has been true when we have gutted out kitchens to remodel, we have almost always found fundamental flaws inside the walls and the floors.

In one case the dishwasher was dumping its water and waste directly into the crawl space. After crawling under the house, we discovered that this moisture had caused black mold to grow on the floor joists and subfloor. Of course, we had to tear out the sub-floor to expose the joists and replace them. This was a costly repair over and above the cost of the kitchen remodel.

After a while I got so I would anticipate typical kinds of problems and tell the owner’s ahead of time that I would put these costs into my proposals and estimates. When I found problems behind walls and floors, I always showed the owners and explained how we needed to fix these problems and what it would cost.

On one house we were called upon to build custom cabinets, window seats and shelves for a bedroom on the third floor. When I was about finished with all these fixtures, I sent one of my men up to cut back the carpet for where we would be installing these built ins. After he returned, he had a grim look on his face and he simply said, ‘you are going to have to take a look at this before we do anything else.’

I went up and pulled back the carpet and the OSB subfloor was black and rotten, so much so that I could stick my fingers through it. I immediately went down to the basement and found that the floor ledger and the top wall plate on which all the structure of the house sits was nothing but mushroom compost.

I felt sick. I went up on the roof and found where the rainwater had been pouring into the wall on the third floor. This is one of those houses that has “real” stucco siding. Besides a faulty roof design that I see all the time; the builder or his workers assumed that this stucco was waterproof and had left out any the flashing where this wall met with the roof.

The roof design was funneling water directly against this wall. The result of course was this water ran down inside the wall all the way to the basement. Then I discovered that at this corner of the house the floor ledger and foundation wall plate was directly below the ground and the house sits on a negative elevation from the street and this run off was running against this wall and the basement.

I cannot tell you how badly I felt showing and telling the homeowners the problem they had and how costly this repair was going to be.

We had to tear out sheetrock on walls and ceilings on all three stories to expose the damage. All the OSB sub-wall was eaten up with black mold and the structure both walls and floor joists were infested with termites.

We actually had to jack up the house to replace the floor plate and floor joists and then regrade the front yard to overcome the effects of negative elevation. This was just the beginning of extensive repairs we needed to do to this house because of poor design, failed materials and shotty workmanship.

This was just supposed to be a $2000.00 cabinet job that turned into 10’s of thousands to repair fundamental problems on this house.

To say the least it is extremely important to have carefully prepared detailed house plans that even the general laborers understand, and each plan requires carefully prepared alterations to accommodate the unique features of a specific lot.

Professional builders should know intimately every factor in all phases of construction to understand and expect the eventualities throughout the process and provide careful supervision. I personally do not think you can do this if you are building 10 or 100 houses at the same time.

Owning a house is for most people their single greatest financial investment and should be able to rely on their house being built by competent professional builders whose greatest responsibility is looking for the long-term best interest of those who will dwell in the house they build whether it be 1 or 10 generations that will inhabit that space.

We expect no less from our doctor or attorney and so should be our trust in builders.

I could write volumes on the ghastly problems I have found and repaired in modern homes especially in mass produced houses of which most subdivisions are.

I certainly hope and pray you are among the happy and carefree homeowners who have not fallen victim to the costly maintenance and repairs of the few examples I have described or others.

However, if you are among those who have had costly repairs and wondered what else is around the corner and wondered if there are alternatives to conventional mass-produced houses, then you especially should read on.

By the mid 1990’s I had become so tired of making my living at the heartbreak and expense of my clients. I had become truly cynical of conventional building materials and general building practices and what galls me the most is the audacity to call these materials and methods: “green construction”. I hate that term especially when it means nothing and all it benefits in the end are material manufactures and large construction companies.

First of all how can we call stick frame construction green or especially sustainable construction? We cannot continue clearing land and forest to build temporary structures that likely will be mowed down in 20 years to build more temporary structures that appeal to the latest trend or fashion.

This may be great for capitalism and financially sustainable to those I have mentioned above and others, but it is murder on our environment and cannot go on, because our forests are so critical to our survival on the earth.

We cannot continue building low thermal mass houses that consume so much energy to heat and cool. It is really a whole lot like thinking we can heat and cool the outdoors.

I made it my mission to design and build houses for my clients that are truly sustainable by being low cost to maintain, highly energy efficient and designed and built as durable, reliable structures that will serve the dwelling needs of many generations.

This meant I would be able to find building materials and methods of construction that overcome the typical issues I was facing in remediation of modern houses and would be energy efficient enough to be able to justify the initial costs of heating and cooling systems which truly utilize sustainable renewable energy.

My aim was not to find a cheaper way of construction but to look at long term cost in energy and maintenance for houses to last at least a hundred years. This is not only good for the environment, but more the people who will inhabit these houses that they make their home. I hate short sightedness and I was determined not to be so or ignorant especially of alternatives to the status quo.

I had learned enough from my historical restoration experiences to take into account using simple principles of thermal dynamics and especially of utilizing the direct and passive energy of the sun and to take advantage of natural convection air flow.

Furthermore, simple things like designing houses with covered porches and deep eaves and soffits to reduce the effects of the sun upon windows and doors and building structures and to provide shading to reduce solar gain and decrease cooling costs and to orient houses to the sun to take advantage of passive solar energy in the winter to reduce heating loads. Not only do porches provide practical purposes for reducing energy consumption, but they are welcome spaces for outdoor living.

I am also an avid advocate for using Evacuated Tube Solar thermal collectors for domestic hot water and water source heating and cooling. They are relatively inexpensive as compared to solar voltaic collectors. When you design and build for high thermal mass and not working against nature and its principles it only makes sense to utilize sustainable renewable energy systems that are initially more expensive to install than conventional HVAC, but the long-term energy savings are incomparable.

My next objective was to find building materials that stand up to the test of time, do not rot or become subject to insect infestation, will not burn, and can effectively stand up to harsh conditions like high winds floods and even earthquakes. I knew I was looking for a whole building system and not just a particular building material.

I knew that a composition building system like conventional frame construction could not stand up to high winds, floods, and earthquakes because it is not a monolithic system that can move together under such conditions, much like a ship on the sea. Instead, it is only as strong as its weakest link.

When a part of the system is imposed to high winds for example it moves and pulls against the rest of the structure unevenly and consequently pulls itself apart and the whole system fails.

From my experience with historical buildings, I knew that the best system would be a solid form of construction. I had seen solid brick and stone structures that have remained reliable for hundreds of years. I also was familiar with tabby-built houses and hay bale houses that have long stood the test of time and the weather it has endured over centuries.

I have also had experience in designing and consulting on construction of rammed earth structures. There are adobe houses that are over 400 years old and do well in a certain kind of environment but not suitable to a variety of regions. I was looking for something that would perform in very diverse conditions and regions.

I am familiar with all kind of masonry construction and they all do better than stick frame construction. They have two major drawbacks. They are put together with thick bed sand and cement base mortar and the joints can become weak and under extreme conditions collapse. The other drawback is these systems do not have a very high thermal mass relative to their thickness.

I did extensive research looking for the right material and building systems that met with my criteria. As you might have already gathered, I am skeptical of the high claims building manufacturers have made about their products and have seen them fail. I was looking for a material that had already proved itself over a long period of time.

I was pretty sure that such a thing was not available in the United States and began to think I would have to create a niche in construction making houses out of such things as post-consumer waste like old tires, glass and plastic bottles and cans and knew I could do it, but it was a market for just a few people and not financially sustainable for me.

I also considered designing and building rammed earth structures, but here in Georgia where I live our heavy dense red clay and our climate are not well suited for this form of construction.

So, I started exploring materials and building systems in Europe where forests are already depleted and framed construction is frowned upon. Solid construction is the norm in most of Europe and I felt there had to be a solid material and building system that was both monolithic and proved over a long period of time in diverse climates and could meet the criteria of being fireproof, water resistant and not compromised by moisture.

It also had to be insect proof especially to our termites and have high thermal mass. Secondarily I was looking for a product that would lend itself well to all kinds of architectural styles and lastly be user friendly so I could teach American workers on how to build with this product and construction system.

I discovered a product that was invented and patented by a Swedish architect in 1924. His name was Dr. Johan Axel Eriksson who was working with Professor Henrik Kreuger at the Royal Institute of Technology in Sweden.  They called it cellar concrete. By 1929 a factory was built in the town of Yxhult and the name of the manufacturer is Ytong.

In 1939 another production company, named Siporex heighten the popularity of this material and it began being used widely throughout Europe. Soon they had operations in 35 locations worldwide. Autoclaved Aerated Concrete designs (AAC) is made under several names: Autoclaved Cellular Concrete, Aircrete, Thermalite and Hebel.