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oar 11-25-2006 03:52 PM

AAC or standard CMU blocks

I want to build a house in Florida using surface bonded concrete blocks.
I like standard CMUs since these can be dry stacked (mortarless) but then it will be necessary to insulate the exterior walls outside.

If I use autoclaved airated concrete (AAC) blocks then the wall itself will provide the insulation but I have to use mortar. With AAC I do not need surface bonding, I need only ordinary stucco.

But I like the idea of surface bonding cement since it increases the wall strength and seals against water. Can this be applied to AAC blocks and how much more expensive is this than ordinary stucco.

Would it be cheaper to go with fully grouted ordinary dry stacked CMUs and ouside insulation on the exterior walls. What sort of insulations are recommended here?


concretemasonry 11-25-2006 05:03 PM

AAC or standard CMU blocks
A portion is already answered on a different thread.

Dry stacked masonry is not as easy as you think it is. In your area, you may find it cheaper to have a masonry contractor to do the block shell. That is the reason for the current method of building masonry homes in Florida. With dry stacked you still have to address the problems of uplift, roof anchorage and the hurricane projectile protection (depending on your county). You do not just stack the block and will have to insure the wall is truely vertical and provide shims or intermediate mortar joints to keep it true. Remember, you are stacking 8" wide block up 8 or 10 feet with nothing to keep them vertical.

AAC is an old European building material that has a high material cost. It has been very successful in northern European areas where wood is thought of as good only for low cost construction and where the cost of the materials was government subsidized. It can be laid with thinset, convential mortat or even surface bonded. I do not know if it qualifies to be used as a substitute for concrete block in the areas that require protection from hurricane driven projectiles. Wood certainly is inadequate.

Surface bonding does not increase the "wall strength". It has higher fexural strength and lower compressive (vertical) strength. Most problems I have seen are shear problems on wall with ligh lateral loads.

You can only find out what is cheapest for your home by putting together the options and getting prices for them. By doing a portion of the job your self, what you can (and want to ) do, makes it a little more complicated to put the picture together.

In the end, your masonry home will be worth more than a stick or wrinkled tin stud home.

GreenLiving 06-09-2008 11:08 PM

Try Liteblok
There is a block out there called Liteblok from Cresco Concrete Products in Houston. It will do what you want. It's cost effective, lightweight, interlocking, and mortarless. You can just finish the walls with thin stucco.

yes.itsconcrete 06-10-2008 06:43 AM

in islamorada,,,
which, in your considered opinion, would be best, dick,,, icf's, cmu, or aac's,,, my thinking's icf's #1 w/grout filled cmu 2nd - both steel reinforced.

thanks - john

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