# Hanging sheetrock against blocks w/ F26?



## Python49 (Nov 16, 2011)

Hey guys, I am trying to double check on information being given to me by local contractors who say that you can F26 sheetrock against blocks just fine and it will be secure for years. Is this accurate? Also, what would the insulation value be like for a block wall that has been stucco'd + painted over on the exterior and then sheetrocked on the interior? I am trying to decide if it's necessary to incur the additional costs of furring this particular wall out or if we can just sheetrock right on the blocks. I was just a bit concerned about how longlasting this would be.


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## cdwoodcox (Jan 3, 2011)

I normally use 1'' mason nails or tapcoms and a whole bunch of glue. If the wall is an exterior wall I would recommend priming with an oil base primer so fastener's don't show discoloration through paint.


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## SlimPickins (Aug 10, 2010)

Is the exterior stucco done over rigid foam? If so, that stuff is R5/inch....so you're maybe looking at R10. CMU has negligible R-value, as does drywall. I'm with CD on this, I use fluted masonry nails or tapcons too...gotta fasten it somehow unless you're going to build a sh!tpile of braces:blink: If you're worried about insulative value, I'd suggest furring the walls out.


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## Python49 (Nov 16, 2011)

No they did the exterior with stucco right over the block. For the interior I'd prefer some insulation value if possible just not sure what all the options are. If I have them put drywall right against the block on the interior and the exterior is just stucco, I'm thinking that would be very little R-value. I might just have them furr the walls out which would allow for some insulation, as well as a way to sheetrock up against.


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## cdwoodcox (Jan 3, 2011)

Dude if it is your house just have them furr wall out and insulate. How long is the wall in question.


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## SlimPickins (Aug 10, 2010)

Python49 said:


> No they did the exterior with stucco right over the block. For the interior I'd prefer some insulation value if possible just not sure what all the options are. If I have them put drywall right against the block on the interior and the exterior is just stucco, I'm thinking that would be very little R-value. I might just have them furr the walls out which would allow for some insulation, as well as a way to sheetrock up against.


Well, if it's a storage unit don't worry about it. If it's a house or a business, fur it and insulate. It all depends on how much you want to spend and how well you want to be insulated. Rigid foam against the block, then build a 2x4 wall and put your R11 in it....that'll give you R21 and the rigid will stop all the drafts from getting in. Or you could just build a 2x4 wall. Or a 2x6 if you want R19. Your climate probably plays a role in this too......


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## Checkers (Jun 25, 2010)

CMU Block walls have an R-Value of 1. You can light a match on one side of a block wall and a thermometer can detect it from the other side lol.


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## Python49 (Nov 16, 2011)

Hmmm yeah I guess I should probably just keep it simpler and furr the walls out and then insulate. The blocks btw were filled with concrete if that matters at alll as far as insulation value and thermal mass.


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## Checkers (Jun 25, 2010)

The R-Values are as follows:
Concrete Block 4" 0.80 Concrete Block 8" 1.11 Concrete Block 12" 1.28Poured Concrete 0.08/inch 
So an 8" Concrete block filled with 5 inches of concrete give you an R-Value of about 5.


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## storming34 (Nov 25, 2011)

Python49 said:


> Hmmm yeah I guess I should probably just keep it simpler and furr the walls out and then insulate. The blocks btw were filled with concrete if that matters at alll as far as insulation value and thermal mass.


*Python49, *
As a suggestion you could go with 1 ½” 25ga Z-Furring/1 ½” Foam board @ 24”o/c, the hang board to furring. It uses less space and offers R-Value w/vapor barrier .
Click or copy & paste link - http://www.foamular.com/foam/products/insulpink-z.aspx
When I install the z furring/foam I use a Trackfast gun. 
You can get the Z furring from any commercial supplier.


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