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make up of gypsum board?


vtdutchman's Avatar
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11-01-10, 07:48 PM   #1  
make up of gypsum board?

I have done a few dry projects over the past several years, but this is the first using 5/8 inch drywall. I scored it and snapped it and it looks (and feels) like there is fiberglass in the board. I did not buy anything special, just the run-of-the-mill board. After about an hour of working with it I am noticing small cuts all over my hands. Has anybody ever noticed fiberglass in the make up of drywall? I did not buy green board or any other special type.

 
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11-02-10, 03:23 AM   #2  
Welcome to the forums! In order to lighten the load, some manufacturers are including a fiberglas in their gypsum. It makes it stronger, too. I've never had cuts on my hands from it, but I can't discount the possibility.

 
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11-02-10, 10:16 PM   #3  
Vtdutchman:

I expect this fiberglass is meant to increase the fire stop rating of the drywall you bought.

In a fire, drywall acts as a fire barrier because the gypsum core contains a lot of H2O chemically bound up in the gypsum core. In a fire, the gypsum core of drywall can't exceed the boiling point of water (212 deg. F) until all of that core has been converted into Plaster of Paris powder. Consequently, the gypsum inside drywall keeps the wooden wall studs cool (below 212 deg. F) until all of that gypsum core has been converted into Plaster of Paris powder by the heat of the fire.

The problem is that often during a real fire, the paper facing on drywall will burn off, and the interior gypsum core will break away, leaving the wall studs the drywall was fastened to exposed to the much higher temperature of the fire.

The idea of adding fiberglass to the gypsum core of drywall is to ensure that even if the paper burns off of the drywall, the gypsum core will hold together, thereby allowing a full half hour of protection to the wooden wall studs.

 
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11-03-10, 03:28 AM   #4  
I agree, Nestor, but I can't see the fiberglas as being a primary fire retardant, since, as you say, the paper burns off, and the gypsum is left to fall off. Wondering, too, what they are putting in the new lightweight sheetrock. We used some the other day on a remodel and my guys said they could detect the difference in weight of a full sheet. Probably whip more air in the mixture.

 
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11-03-10, 07:03 AM   #5  
Posted By: chandler I agree, Nestor, but I can't see the fiberglas as being a primary fire retardant, since, as you say, the paper burns off, and the gypsum is left to fall off.
He saying the paper burns off but the core stays together due to the fiberglass holding it together.

The idea of adding fiberglass to the gypsum core of drywall is to ensure that even if the paper burns off of the drywall, the gypsum core will hold together
Great info Nestor!!


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11-03-10, 06:59 PM   #6  
But, Scott, if the gypsum is left to "fall off", what do you have left? And 212 F ain't squat in a fire. I guess it would keep things under control as a fire starts, but fully engulfed probably not.

Larry

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