# 3/8" Drywall Installation Question



## pjmachine (Feb 26, 2008)

Have been working on a 2.5 story stairwell which previously had paneling on top of ¼” plywood. The plywood runs behind the stair stringers (and some additional framing) so removal is not an option without doing a lot of demo/cutting. My question is, if I were to install 3/8” drywall will there be enough support between the studs to allow for horizontal sheet installation (rather then vertical) simply because it would look much nicer (fewer butt seems). I’m concerned about too much flex in the sheets between the studs that would cause the horizontal seems to crack . . . been considering using adhesive at the seems in addition to extra screws into the ply in between the studs. All studs look to be 16”oc.

Any comments would be appreciated - Thanks!


----------



## jerryh3 (Dec 10, 2007)

So the end product would be 3/8" drywall over 1/4" plywood? It shouldn't be that much of an issue. Just glue heavy and make sure the screws aren't driven too far in.


----------



## Handyman50 (Sep 28, 2007)

Drywall is normally installed over the studs without any backing. Granted, the norm is 1/2" drywall. In your case, the 1/4" plywood should be enough to make up the difference. If you are assuring that the butt seams meet on a stud, there should not be a problem with cracking. If you are going to simply have the seams meet between the studs, I would be a bit concerned about the flex as you suggested. You can use a stud finder to locate the studs.

I have a wall that flexes when the door is closed too hard. There are butt seams on it that have cracked. This is why I am concerned about not meeting on the studs.


----------



## AtlanticWBConst. (May 12, 2006)

Re-nail all plywood. In fact, you should use a pnuematic *stapler*, if you have access to one.

Do not use 3/8" S/R. 
Use 1/2" with your 16" OC framing.

When you install your sheetrock using 1-1/4" course thread screws (for wood framing - fine thread is for steel), that will "sandwich" the 1/4" plywood. It will not go anywhere, nor will it make any difference in the sheetrock application. There is no need to glue the sheetrock onto the plywood, as it will also, make absolutely NO difference with the installation.


----------



## Handyman50 (Sep 28, 2007)

AtlanticWBConst. said:


> Re-nail all plywood. In fact, you should use a pnuematic *stapler*, if you have access to one.
> 
> Do not use 3/8" S/R.
> Use 1/2" with your 16" OC framing.


AWFC, why, since he has a backer of 1/4" plywood, would it be necessary to use 1/2" S/R? I would always use 1/2" in any instance, but why in this application? This is for my knowledge. Thanks!:confused1:


----------



## AtlanticWBConst. (May 12, 2006)

Handyman50 said:


> AWFC, why, since he has a backer of 1/4" plywood, would it be necessary to use 1/2" S/R? I would always use 1/2" in any instance, but why in this application? This is for my knowledge. Thanks!:confused1:


I do not consider 1/4" plywood over 16" OC framing, as a proper "backerboard" (to any degree)...

Example: Installing 1/4" cement board over 16" OC rough framed walls...is not a backerboard for tile.

3/8" S/R. is not meant to be used on 16" OC framing. It is primarily used, to be installed onto a solid surface. Example: we only use it to build out surface areas, or to overlay onto existing GWB walls.

Because there is existing 1/4" plywood over the 16" OC framing, should not be a reason to drop down to a 3/8" GWB. In fact, the plywood, itself could have irregularities in it, that can transmit, visually, to 3/8" GWB. You should stick with the standard 1/2" for 16" OC, to be safe. The additional cost is reasonable.

Side note: GWB = Gypsum Wall Board (just in case someone is not aware. Industry term)


----------



## pjmachine (Feb 26, 2008)

Thanks for all the comments. To reply to AtlanticWBConst post, I was just on Sheetrock brand's web site and they have a pdf regarding installation/finishing of their products. They do state that 3/8" sheetrock may be installed horizontally or vertically with 16" oc max spacing in a single layer application, similar to 1/2". Their requirements for 1/4" are different. I guess that also answers my question, but all of your comments have been very useful.


----------



## Handyman50 (Sep 28, 2007)

AtlanticWBConst. said:


> I do not consider 1/4" plywood over 16" OC framing, as a proper "backerboard" (to any degree)...
> 
> Example: Installing 1/4" cement board over 16" OC rough framed walls...is not a backerboard for tile.
> 
> ...


Thanks, AWBC. As I said, I wanted to hear the reasoning of a pro.:thumbsup:


----------



## jerryh3 (Dec 10, 2007)

pjmachine said:


> Thanks for all the comments. To reply to AtlanticWBConst post, I was just on Sheetrock brand's web site and they have a pdf regarding installation/finishing of their products. They do state that 3/8" sheetrock may be installed horizontally or vertically with 16" oc max spacing in a single layer application, similar to 1/2". Their requirements for 1/4" are different. I guess that also answers my question, but all of your comments have been very useful.


My house, which had a remodel sometime in the 70's, had 3/8" on some of the walls. I would never use it new construction though. The only time we ever used 1/4" was when doing curved walls and ceilings. We would laminate two sheets together.


----------



## AtlanticWBConst. (May 12, 2006)

pjmachine said:


> Thanks for all the comments. To reply to AtlanticWBConst post, I was just on Sheetrock brand's web site and they have a pdf regarding installation/finishing of their products. They do state that 3/8" sheetrock may be installed horizontally or vertically with 16" oc max spacing in a single layer application, similar to 1/2". Their requirements for 1/4" are different. I guess that also answers my question, but all of your comments have been very useful.


 
It is your home, you may do as you wish. I still don't understand why you want to attach 3/8" sheetrock over rough framing. 
Regardless of the sheetrock manufacturer's site information, I still do not recommend it. 1/2" Is the industry standard, for the reasons stated earlier.
(FWIW: In all the years we have been in business, we have never seen 3/8" S/R installed over 16" OC rough framing, by a professional contractor - in new construction, remodeling, repairs, or any other applications)

What ever you decide to do, Good Luck on your project.


----------



## jerryh3 (Dec 10, 2007)

AtlanticWBConst. said:


> It is your home, you may do as you wish. I still don't understand why you want to attach 3/8" sheetrock over rough framing.
> Regardless of the sheetrock manufacturer's site information, I still do not recommend it. 1/2" Is the industry standard, for the reasons stated earlier.
> (FWIW: In all the years we have been in business, we have never seen 3/8" S/R installed over 16" OC rough framing, by a professional contractor - in new construction, remodeling, repairs, or any other applications)
> 
> What ever you decide to do, Good Luck on your project.


Agreed. If you don't need to use 3/8", don't. I thought you needed to use it for clearance issues, but if you are able to use 1/2", use it.


----------

