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oar
Joined: 25 Nov 2006
Posts: 4
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 Posted: Sat Nov 25, 2006 4:53 pm Post subject: standard concrete block or AAC? |
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Hi all,
I want to build a house in Florida using concrete block walls.
I like the idea of dry stacking (mortarless) the blocks with surface bonding since this simplifies the masonry work and speeds it up.
I could do this with standard CMUs fully grouted in the cores but then I would have to apply insulation on the exterior
walls outside to make use of the thermal mass inside the insulation. How expensive is this, what are the aesthetic considerations? I would then probably have to put stucco on the insulation, seems wasteful given that the blocks are already surface bonded. What sort of insulation would you recommend here?
The alternative is to use autoclaved, airated concrete (AAC) blocks where the wall itself provides the insulation.
Generally these use some mortar. I wonder if these can be dry stacked and surface bonded too (seals against humidity too).
The AAC blocks are apparently easier to work with.
Which solution is preferable here? Is one significantly cheaper/better than the other?
Thanks |
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RWL
Joined: 10 May 2004
Posts: 399
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| Posted: Mon Nov 27, 2006 9:40 am Post subject: |
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Does the applicable building code allow mortarless construction?
CMU would be cheaper more than likely as they are standard and commonoly mass-produced product, unlike the AAC that, as far as I know is custom made for project requirements.
It strikes me that the whole process, in the case of a house, is much simpler with standard CMU. |
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arkiwiki
Joined: 29 Nov 2006
Posts: 12
Location: Portland, Oregon
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| Posted: Fri Dec 08, 2006 1:30 am Post subject: |
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| RWL wrote: | | It strikes me that the whole process, in the case of a house, is much simpler with standard CMU. |
AAC is also simple to install. Many contractors out there and ifyou decide to DIY it should be too difficult to see how things work.
The initial cost is about 3$-$4 sqft but it the savings you get from lower energy consumption and maintenance is much better in the ong run.
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greenrnb4
Joined: 12 Dec 2006
Posts: 3
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| Posted: Tue Dec 12, 2006 4:53 pm Post subject: Another alternative to CMUs |
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Have you looked into using Insulating Concrete Forms (ICFs)? They stack up dry and provide superior stay-in-place insulation, 8-10 times the wind resistance strength of 2x4 framing, and excellent termite, mold and fire resistance.
I recommend Amazon Forms ICF. They are made from cement and 100% recycled styrofoam, much heavier than most ICFs so they're less likely to blow down before pouring the concrete, yet light enough for DIY builders. They cut w/ common wood-working tools, use ~40% less concrete than flat ICFs, and you can stucco or plaster directly to them.
Check out www.amazongridwall.com
Disclosure: I work as an engineer for Amazon Forms. That said, I was an advocate of the product even before joining them. After years of studying all the other wall systems available, including AAC, I pestered the good Amazon folks until they hired me. No regrets. |
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csintexas
millennium club
Joined: 06 Feb 2006
Posts: 1919
Location: USA
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| Posted: Thu Dec 14, 2006 10:14 am Post subject: |
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Nice product, I like the recycled aspect.
An electric bill of $436 in August seems rather average. My house is 3250 sq. ft. and our bill last august was $192 (we also use gas WH). I used standard building methods.
As to the original post (from the little I have read on AAC blocks) proper installation seems to be more difficult than standard CMU
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Chris Stewart
Modern Texas Home Project |
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greenrnb4
Joined: 12 Dec 2006
Posts: 3
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| Posted: Fri Dec 15, 2006 9:05 am Post subject: Clarification of electricity |
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Don't mean to be argumentative or hog this thread  but...
The Grid-Wall demo house w/ $436 Texas August electricity bill included pumping water to supply not only the house, but 2 acres of landscape, a Texas-sized "garden", and a 40x60 green house. Ideally the owner should have used zone metering to capture the actual use of the house, but didn't.
A San Antonio Grid-Wall house owner reports her monthly energy bill is lower than in her previous house, though her new Grid-Wall house is twice the size of her old house. That kind of reduction is typical if the HVAC is sized right and the rest of the envelope is constructed for efficiency.
re AAC: I have a church friend who is building her house of AAC and has had a lot of difficulty getting the large panels straight and plumb. She thought they were milled, so would be dimensionally accurate, but found otherwise. When she complained, the mfr. pointed out the fine print in her contract that said the panel dimensions were "nominal". I don't know the manufacturer, and would not condemn all AAC mfrs, or AAC as a viable building material based on one person's experience, but she is very, very  . |
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structuralengineer
Joined: 07 Jan 2007
Posts: 6
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| Posted: Sun Jan 07, 2007 3:50 pm Post subject: |
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I am a structural engineer who has designed serveral residecnes with AAC. It is a great project to engineer with not as strong as CMU but much stronger than timber. You will use less rebar than a typical CMU design unless you elect to add a few more bars. The product has a ICC Legacy report for the design, generally follows ACI 530 strength design approach.
So far I have worked on 3 house in Southern California, Eastern Oregon, Seattle, and Idaho.
AAC is easily worked with and modified in the field.
Regards, |
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mhillerbrand
Joined: 18 Jan 2007
Posts: 1
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| Posted: Thu Jan 18, 2007 8:38 am Post subject: Surface Bonded |
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| What about surface bonding ACC block? Seems like it would be the best of both worlds. Mike. |
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jredburn
Joined: 17 Feb 2007
Posts: 2
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| Posted: Sat Feb 17, 2007 5:59 pm Post subject: |
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Greetings,
I am new to the forum and I am a dedicated ICF builder in S W Florida. The reason we went with ICF is best explained by the picture of the second page of our web site,
<www.rfbhomes.com>
The economics of the system are basically a 60% to 75% reduction in the electric bill. The insurance on a house is 30% to 70% less. We design our houses to exceed the Miami-Dade Hurricane Code. They cost $10,000 to $20,000 more than a CMU house because we use better quality materials and better installation methods.For the stronest,safest, most economical house availabe, look to ICF.
Regards
Joe Redburn |
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daveinsingapore
Joined: 17 Aug 2007
Posts: 1
Location: Singapore
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| Posted: Fri Aug 17, 2007 11:04 pm Post subject: AAC blocks.....or CMU |
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| hello people...I am a new to this site...I work out of Singapore and spent my life in New Zealand...now looking at the original question..AAC blocks versus AAC blocks...I use AAC blocks here in Indonesia and would never go back to CMU again...the energy savings are only part of the benefits..the construction time is quicker...I design and build for earthquakes and so use reinforcing steel in a beam formed between 50mm thick blocks and standard concrete mix...as well as vertical rods from the foundation beam to this beam as well...fitted in predrilled holes every meter and either side of doorways and window openings and then backfilled with a mortar mix....there is no use of bulky mortar between the AAC blocks...but a thin bed adhesive which is supplied with the blocks and forms a totally homogenous construction method....this method of building works really well and is well worth the effort. |
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houstongreen
Joined: 28 Jul 2008
Posts: 1
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| Posted: Mon Jul 28, 2008 7:55 am Post subject: Check out Liteblok as an option |
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| New to the US, Liteblok is an aerated, interlocking, dry stacked, lightweight block. A 5" block will give you R-22 in South Florida and it's priced (wall cost) at less than 2x4. Liteblok is an Australian invention spreading around the world. Visit www.CrescoConcrete.com. |
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