Trying to answer a few AAC questions

Comments   2   Date Arrow  January 30, 2008 at 3:31pm   User  by Christina

Since starting the blog we have loved the questions we have received from all those interested in building with AAC. I decided to respond to this comment as a post so that the q&a didn’t end up too buried. I felt that others out there might also benefit.


The comment:


My wife and I have designed a house that will be built on a 2 acre lot we purchased in the beautiful Texas hill country. We have also made a decision to go with AAC and will be using Contec here in San Antonio, Texas as our vendor. We are discussing trying to do all the interior framing in AAC versus wood. Do you see any drawbacks with this strategy? Additionally, I read Christina’s comment regarding specific chases for the electrical and plumbing. I assume this could be handled by strategically placing o-blocks for the needed chases. Lastly, we thank you from the bottom of our hearts for creating this blog. It was a tremendously helpful read.


Basil & Sophia


My response:


Thanks for the positive reinforcement!!!!


I suppose the Texas hill country has similar climate to us in Memphis and that the AAC will suit you very well. I may have mentioned in a past post that we seem to be using very little heat (outside temps vary in the 30’s up to the 50’s now) inside to keep the temperature comfortable. We will have to see how this all works out once we live in the house. The master shower wall is still exposed AAC right now awaiting its’ skin of tile. This wall is not cold to the touch as a typical block wall would be in this temperature.


Contec is great to work with. Charles was who I spoke with during our design phase. We ended up using Aercon at the last minute due to shipping costs. For you in Texas, Contec should be perfect.


I am sure that you can use the AAC for interior framing. This really all depends on your house design, budget, and your needs. If you use the block on interior walls, you will have an 8″ thick wall. For our plan that thickness took up too much valuable floor space. Thus a 4″ wood framed stud wall made more sense. We also have alot of interior walls, but if your plan is fairly simple with few interior walls then the 8″ block might make sense. For us the block itself is more expensive than the wood framing, thus it would have made the project too costly to use the block inside. We also don’t really need the thermal insulation value on the inside of the house that the block provides. We did use typical batt insulation on many of the interior wood framed walls for sound insulation (we can already tell that our house is very quiet inside).


I suppose an o-block would work for a chase but I am not sure? I suggest you try to get an o-block from Contec and discuss this with Contec, your builder, and plumber (since the plumbing pipe has the largest diameter that will need to go through the o-block. The o that is cut in the block may be too small for plumbing? If you have the Contec design manual, they show a plumbing chase example in one of their drawings. If you don’t have this manual yet, you need to request it right away. It will help the construction make much more sense. Based on this drawing and our experience, I would recommend using the regular block but cutting it to form the chase in the wall as the block is installed. We routed the channels for plumbing and electrical after the block was installed thus there was a bit of labor in cutting- but it all worked fine.





Maybe this photo of the plumbing at our kitchen helps. The masons cut the first two or three courses of block as they were laying it because the plumbing rough-in was already in place coming through the slab (notice how the block edges on the left have a smoother cut and the right edge is rougher). They could have continued to create this chase as they laid the block on up the wall creating a chase. However they stopped after the first course or two. After that the horizontal cuts (which are probably a bit wider than recommended) and the cut for the valve were made latter as the plumbing was installed. If you are going to use chases this will require alot of stratgic planning on your part with the plumber/electrician and if you are installing the plumbing and electrical yourself then this may make sense for you.


If you have an electrical plan this will be helpful in locating chases for the wiring. Again we cut ours in after to block walls were in place. It’s doable but with careful planning chases may provide a cleaner option.


Since only our exterior walls are block, we tired to keep as much plumbing and electrical work from being in these walls. Another reason that using stud walls was helpful for us is that the majority of this work occurs in our stud walls to keep from cutting too much block.

I hope that this at least starts to answer your questions. Good luck with all and post another comment to us if you run into more questions.

Tagged   General


  • #1.   Dan Levy 02.07.2008

    Dave and Christina,
    Regarding the question you received about using AAC for interior walls, other options are 4″ and 6″ block in various sizes and possibly panels though they are more appropriate for large expanses with few openings. The appropriate thickness depends on factors including load requirements, height of the wall, and how many edges of the wall are attached to the structure or are free standing. Cost of AAC may be greater than wood framing, but you gain on longevity, fire resistance, and sound deadening. For plumbing chases in interior walls, you can leave a gap in the full thickness of the wall and attach a wood cleat to each side of the opening. Size the cleats so they are recessed on each side of the wall by the thickness of drywall or tile backer and attach the board to cover the opening. If plastering the interior, use fiberglass mesh tape to bridge the gap between dissimilar materials.
    Keep up the great work.

  • #2.   Dave 02.10.2008

    Great thought, Dan. Of course there’s no need to use an 8″ block inside!

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