# hanging sheetrock/drywall question



## eis61374 (Oct 4, 2008)

Hi all,
When hanging drywall, how close to the sub-floor should the drywall panels reach? I live in a 3rd floor condo & have a concrete sub-floor. 
I ask because after taking up the floor I can see that the drywall does not extend all the way to the subfloor.
Sorry for the newb question.
Thanks in advance.


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## AtlanticWBConst. (May 12, 2006)

It is a good practice to place a spacer underneath the sheetrock, when installing on the walls. Sometimes, it's a scrap peice of sheetrock (1/2" -5/8"). sometimes, it's a scrap of wood (3/4"). 

There are Two fold beneficial reasons. 

In all installations: Because it raises the sheetrock away from the base of the wall/floor, where there are common protrusions (nails from wall-raising), debris, etc. This allows the sheet to sit flat, as opposed to "kicking-out" slightly at the bottom edge.

With Concrete Floors: All concrete is porous & contains a certain amount (%) of moisture. Some areas more so than others. Thus, it is a good practice to have a gap between the concrete and the sheetrock, so that the sheetrock does is in direct contact to such a surface.

Now, on the other hand, the sheetrock should not be raised so high up off the floor, that a gap is left (above the bottom plate), that you can see open wall bays. This is especially so the case, in specific walls of buildings (apartments/condos, commercial, etc), because of fire-separation wall factors/codes.


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## Maintenance 6 (Feb 26, 2008)

AtlanticWBConst. said:


> It is a good practice to place a spacer underneath the sheetrock, when installing on the walls. Sometimes, it's a scrap peice of sheetrock (1/2" -5/8"). sometimes, it's a scrap of wood (3/4").
> 
> There are Two fold beneficial reasons.
> 
> ...


I believe Atlantic must have been in a hurry.  He missed a key word. Sheetrock should NOT be raised so high up off the floor, that a gap is left that you can see into the open wall bays.


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## AtlanticWBConst. (May 12, 2006)

Maintenance 6 said:


> I believe Atlantic must have been in a hurry.  He missed a key word. Sheetrock should NOT be raised so high up off the floor, that a gap is left that you can see into the open wall bays.


You are right on both accounts. 

Thank you for catching that and correcting it.


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## eis61374 (Oct 4, 2008)

Thanks!!! Now, after removing all the wood flooring, plywood underlayment & sound barrier its clear that the drywall DOES extend all the way down to the concrete subfloor in 95% of the room. So, can I simply use a drywall saw (or something similar) to cut away the bottom 1/2" or 5/8" of the drywall?


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## Maintenance 6 (Feb 26, 2008)

I see no reason why you couldn't. Just don't cut so high that you enter the stud cavities. I have taken a block of wood with a utility knife blade screwed to it and slid it on the floor and along the wall to cut drywall for clearance.


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## DangerMouse (Jul 17, 2008)

good trick m6, i like that idea. hafta slide it a few times to go all the way through though....

DM


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## Termite (Apr 13, 2008)

To expand on what AtlanticWBconst said, I'd caution you against removal of sheetrock on any of your exterior walls, interior bearing walls, or walls that are shared with corridors or other units. In multilevel/multi-unit construction, those are fire-rated walls and the installation of that rock is done in a very specific way to ensure the integrity of the fire rating. If the rock does not extend to the bottom plate of the wall (which is 1-1/2" tall on top of the subfloor deck), then somebody really screwed up in the construction of the building. 

Why do you need to remove any of the rock at all?


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## DangerMouse (Jul 17, 2008)

moisture? 

"With Concrete Floors: All concrete is porous & contains a certain amount (%) of moisture. Some areas more so than others. Thus, it is a good practice to have a gap between the concrete and the sheetrock, so that the sheetrock does not make direct contact to such a surface."

DM


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## eis61374 (Oct 4, 2008)

Hey termite,
I'm really just trying to figure out if the sheetrock should or should not extend all the way to the concrete. Nothing in this building has been built properly, and we, the owners, have had to hire an independent company to inspect the entire building, but I am trying to learn as much about my unit as I can so that I can make sure any repairs/rennovations/improvements it needs are done properly. I have had no luck trying to get an answer from the NYC Dept. of Bldg's regarding building to code & I'm confused because there is very clearly one area where a single sheetrock panel is a good inch from the concrete.
Thanks to everyone for all the answers so far!!!!!


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