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Any experience/opinion with AAC (Autoclaved Aerated Concrete) construction?

I am planning to build a shop/garage (40X50)and have been looking at options. Would like to build myself with the help of my sons.

A Fine Homebuilding book on foundations and concrete had articles about ICF (insulated concrete forms). This looks interesting, but would require finishing both the inside and outside walls- and before that a concete pumper and lots of concreted for a small -no actual experience- crew to be ready for. The book also talked about surface bonded concrete block, which uses a high strength fibered mortar put on like stucco on both sides of dry stacked concrete blocks (no mortar between the joints. It also uses threaded metal rod to tension the wall. ---Mandatory Metal Content--- Have Lathe-do not need allthread.)

In researching the above on the Net I ran across the AAC blocks. These are blocks made with concrete and an agent that causes it to foam before it intially sets up in a large mold. The green "loaf" is then cut into peices of the desired size and autoclaved- which I assume cures it at an accelerated rate. This is reported to be a common form of construction in Europe for the past 50 years, but relativly new to the US. You can get it in a variety of sizes and shapes, not just blocks.

What I am interested in using are the blocks, which can be purchased as 8x8x24 at a wt of about 37 lbs. The blocks are solid, can be cut with woodworking tools, and are laid up with thinset mortar. This produces a solid wall, which is termite and rot proof, has no voids for air infiltration, an R value of about 10- but this is claimed to have the effect of a greater R value because of the thermal mass. There needs to be special stucco or paint used, which needs to be both elastic and allow water vapor to pass. I believe the latter is to allow the blocks to fully dry out, which takes 1-2 years after manufacture.

Any one have any experience or opinion in their use?

Reply to
JRT
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I looked for this material after reading about it a year or two ago, and could not find it anywhere near me. Shipping concrete (even foamy concrete) gets expensive, so I passed it by. I will say that an R10 wall is an R10 wall, and you believe hokey claims about magic thermal mass at your own risk. Thermal mass helps to slow transitions, but it does not reduce your heating bill when it's -20 out. If you can insulate the exterior before stuccoing, the thermal mass will do you some good. If you insulate the interior, it will do you almost no good. If you don't add any extra insulation, I hope that you live in a mild climate.

Reply to
Ecnerwal

I looked at it last year, but couldn't find a mason in my area that had ever heard of it. The joints are 1/8" thinset. The inside and outside must be coated to inhibit moisture. The vendor has a suggested supplier of same. It really looked good, but I didn't want to become a building contractor this late in my life. I want to macke chips amd cast metal, not build buildings. The nearest builder I could find using the product was in Chapel Hill (80+ miles away). The plant that made the blocks is south of Atlanta, Ga. Freight for enough "stuff" for the walls of a 30x70x10 wall would have been just under $1,000 US. IIRC the brand name was BAAB.

Reply to
keith bowers

And where I live ain't mild enough! (voice of experience here)

Mine has served me well as a solid structure, but I WILL NOT use concrete walls again. My brother-in law is a mason, getting ready to build a new shop, and he feels the same way. He's going with an insulated steel building.

RJ

Reply to
Backlash

I had a house designed with Sparfil block, which sounds like the same thing. Keep in mind that in general (don't flame me here fellows), the construction trades are pretty far down on the technology food chain. I could not find a mason within a 50 mile radius that would even bid on a project using it. It is no doubt wonderful stuff, but unless you have the time, inclination, and tools to do it yourself, I might find another way to get where you are going. Among the design challenges are where to run the wiring and plumbing if you intend to use the inside surface as a finished interior. I saw it used to make a handball court wall. for that, it worked out well.

Kevin Gallimore

Reply to
axolotl

What part of the country are you in?

I am in MO. My thought is that it will be about right in the spring and the fall with the thermal mass helping even out temp swings. As noted in another post, thermal mass is not the same as insultation- esp when very cold.

I started out thinking about a steel building, but keep reading about problems with condensation from temp swings and humidity. We have both.

Reply to
JRT

"The plant that made the blocks is south of Atlanta, Ga. Freight for enough "stuff" for the walls of a 30x70x10 wall would have been just under $1,000 US. IIRC the brand name was BAAB."

That is one source- and the one I contacted. Freight would have been about $1500.

Reply to
JRT

North carolina. Motto here is"If you don't like the weather here, just wait a minute" 27 here now. Concrete shop is too slow to heat up in the winter. It wicks all the heat out of the room until it saturates, which takes a very long time. RJ

Reply to
Backlash

Doing it ourselves was part of the plan. (Sons lift and place blocks, I supervise.)

Part of the appeal is that with the blocks you work at one mixed bag of mortar at a time, block by block. Lots of lifting, but muscle and time can be used to get it done. That and scaffolding.

Reply to
JRT

I explored using them in my garage and decided against it for several reasons. First, I wanted to use them from the footers up which would have put them about 12" underground on the low side and 30" underground on the high side. But AACs are not approved for below grade use - seems you can't be 100% sure that water infiltration won't occur, which can freeze and break the blocks apart. Second, the blocks are solid. So, if you need to run rebar through them you have to drill a 3" hole all the way through, which I figured would be a royal PITA. Third, the blocks were fairly pricy and not worth it when I had to add the cost of stuccoing the outside to protect the blocks. Finally, the local vendor here in Raleigh said they would be happy to deliver them to my house but I needed to provide a fork truck to unload them. Obviously not real eager to work with a non-commercial project.

Steve.

Reply to
SRF

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