Cement block or 2x6 & wonder board ?


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Old 02-23-07, 04:33 AM
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Cement block or 2x6 & wonder board ?

Hi, I have a cement block Octagon in the Bahamas and I want to add a second floor to it. My question is should I stay with block or would I get just as strong of a house if I used 2x6 and wonder board with stucco applied over it? It seems as though costs would be pretty close, perhaps a bit more for the block, maybe ? Which would be stronger ?The wood and wonder board would be a little easier, I think. Any input would be much appreciated.
 
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Old 02-23-07, 04:47 AM
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It seems that the frame construction would be simpler to erect properly than the concrete block, but a view from an engineer may be in order to be sure that the existing walls and foundation can support the added structure. A reference to your local building code may provide some direction, too.
 
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Old 02-23-07, 05:22 AM
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Cement block or 2x6 & wonder board ?

One thing you cannot forget is the hurricane/wind factor.

In some areas wood frame construction would not be approved. It makes little difference whether you use 2x4, 2x6, 2x8 it still falls far short of complying.

There are a few different criteria to consider when building in an area that has had a history. - That is why concrete masonry is to popular where storms are possible.

1. The strength advantages of concrete masonry are obvious.

2. Wood walls do not have the ability to withstand the projection problem with hurricanes/tornadoes. Wonder board and similar materials give little protection. Same thing goes for fiberglass reinforced plywood in tests. Now, many homes in the tornado belt of the U.S. are being built with concrete masonry "safe cells".

3. A wood structure is a "flexible" structure, while concrete masonry is a rigid structure. During the 500-600 home inspections of hurricane Katrina that I saw, the building flexibility caused cracking of wall finishes in the buildings that did survive. This forced a total interior refinishing. Even something as minor a brick veneer on one side of the house provided enough rigidity to minimize cracking. The concrete masonry homes had no interior finish problems and obviously none of the mold problems.

You have a good solid start on your home and should continue with the same type of construction. You will get a better home and most, improtantly, better resale in the future.

Dick
 
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Old 02-23-07, 05:54 AM
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Thanks

I do hear what your saying. I guess I wanted to be able to do a lot of the construction on my own. I don't know enough about cement work to tackle that. I would have to hire it all out. Any ideas on costs of block construction ?
Would I help add rigidity and protect against the projectile damage if I sheathed it with plywood before I applied the wonder board ? Or do you still think I should stick with the block ?
The foundation is 18 inches thick and 4-5 feet deep, so it should hold just about anything I think.
 
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Old 02-23-07, 06:02 AM
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[QUOTE=Wired1;1131361Would I help add rigidity and protect against the projectile damage if I sheathed it with plywood before I applied the wonder board ? [/QUOTE]

When using wonder board on the exterior the correct procedure is to first install plywood/osb, cover with tar paper and then install the wonder board.

I used to live/work in fla and the wood frame structures were required by code to have a lot of metal strapping to help hold everything together during a storm. I've seen builders cheat on the strapping and it is my personal belief that where you have similiar homes, 1 destroyed and 1 left standing, it was because of the building practices used.
 
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Old 02-23-07, 08:56 AM
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Cement block or 2x6 & wonder board ?

The use of plywood would increase the rigidity slightly, but still would not be in the same class as concrete masonry.

Hurricane exposed counties in Florida (14, I believe) have more severe constuction requirements for wind, windows and and projectiles. Extensive tests for projectiles (a 2x4x12' fired from an air cannon at the wall) have found the plywood shething in not adequate, and even if reinforced with fiberglass is not enough. Even block should be partially reinforced and filled. I would imagine your conditions would be as severe, but who knows if the codes have caught up to realistic minimum standards.

If you go with block, your biggest concer will be keeping a roof on the home, so use plenty of good anchors into the concrete.

Dick
 
 

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