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doughboydj
CMU and Spray foam
doughboydj

Hi

I'm planning on building in Melbourne Beach Fl. Very hot and humid.... Was going to build using CMU blocks. Now obviously that isn't a very good wall insulator by itself. I was thinking of having the GC do a 2x4 wall mounted to the CMU blocks interior than have closed cell spray foam used. Any opinions? He originally wanted to do CMU with foam injected into the block and rigid board installed over furry strips. I had this done in a previous house and didn't like the rigin board cause the electricians and plumbers chopped it all up and I felt it lost its insulating qualities. Any suggestions are greatly appreciated.

Clarence
Re: CMU and Spray foam
Clarence

You could look into the use pf ICF.
This would give you a higher PSI wall plus the insulation.

Mastercarpentry
Re: CMU and Spray foam
Mastercarpentry

Insulting CMU's is almost pointless- they have so much conductivity and exposed surface that there's little to be gained doing anything inside of them. What does help is to be sure the tops of every cell is sealed- that maintains the dead-air space inside. I'm not a fan of furring CMU walls out because of thermal conductivity still being there. But building a full stud wall inside the CMU's kind of makes them redundant since the wall alone will do the job.

One thing you're going to have to contend with is that practically all of Florida requires building to codes designed to be hurricane resistant. They are going to limit your options and cause you to build differently than we'd do elsewhere. By the time you take that into account you're probably going to be better off with wood stud construction due to cost factors. Properly constructed wood-frame houses are actually more wind-resultant than un-reinfiorced CMU homes and the same goes for seismic protection. Block isn't as strong as it seems to be and it's only major advantages are fire resistance and lack of maintenance if you leave it bare (which most folks won't do). It can be immensely strong when reinforced but that normally isn't done. In the end it up to you to decide how you want this done.

Phil

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