drywall potential problem

mmhendrie

guys - looking for some advice - i'm building a shower, drywall with kerdi over it. I had to push one wall out half an inch to accomodate a pipe - so i took some 1/2 inch plywood, cut it to stud size strips and nailed them down the studs top to bottom, using pin nails. It seemd strong.

Then i hung my drywall with standard 1 1/4" drywall screws. It's since occured to me that there's only 1/4" of the screw in the stud itself, given the 1/2" drywall and 1/2" plywood, and that there's just essentially a small handful of pin nails attached to a wall that will soon be taking tile.

Is this strong enough? Should I take a few 2" drywall screws and drive them through the drywall/plywood and into the stud - perhaps 4 to a stud so there is a stronger bond between the plywood and the stud? Any thoughts?

Bob Mariani

Add 2" screws. You should have 1" penetration into the stud

Tracymc

Standard GWB, green board, not a good idea even with Kerdi, in a shower stall. From a warranty standpoint neither will hold up, I would address that first if it is. If it is DensGuard, Hardi, Durock or such, 2" Screws are good, I prefer, a climacoat screw for this application, since I have seen some grout staining from water infiltration of poorly sealed grout.
Trace

Bob Mariani

The issue with the green board is it is not stiff enough on 16" OC studs.

mmhendrie

Bob - do i remove my 1 1/4" screws and replace with 2", or can I just add 4 evenly spaced 2" down the studs?

Tracymc - I'm using normal drywall plus kerdi, not greenboard

thanks!

Tracymc

MMhendrie just add screws 16" oc dont waste time removing the 1 1/4" screws.

I understand that you used Reg GWB, even worse, the kerdi is only as good as it's substrate. The issue with reg drywall or greenboard is that it is paperfaced gypsum (degrades and feeds mold and mildew) , no manufacturer will back their warranty if installed in ashower area or tub surround, too many lawsuits. It is for use in areas where moisture resistance is necessary,not for shower or tub surrounds. I would be hard pressed to find an inspector that would even think about passing it. I have pulled apart a 100 failed bathroom installs and 95% of them are due to failure of Grout or caulk, leading to catastrophic failure of the substrate(Greenboard or MR GWB) usually leading to rot and mold in the framing and subfloor, and big repair dollars rather than $30 added cost to do it right the first time.

Trace

mmhendrie

regular drywall is the recommended backing for the schluter shower system...

Ron6519

If I'm putting time, energy and money into a tile job, I am not using sheetrock in a wet area, ever. I don't care what Schulter says. You think Schulter is going to reimburse you when /if the kerdi fails? Baloney!
The likely hood of a homeowner getting the kerdi up correctly their first time out of the box is slim. You need the correct thinset. You need it to be the correct consistancy. You need to install all the little inside and outside corners correctly. And forget about installing niches in the wall.
What gives the homeowner a false sense of achievement is that it works for a while because the water slowly get in and behind the kerdi. It might take months or a year. Then the leak in the ceiling below starts, and we get to open the wall to find sheetrock so moist you can make it into a ball.
So go ahead, use whatever you want. It's not my bathroom.
Ron

Tracymc

MMhendrie
You are absolutely right Schluter say's Reg GWB is okay. Per a conversation with their rep, they will not warranty substrate failure, so what I am trying to convey is that @ the point you are @ now from the sounds of it the Kerdi has yet to be installed and if it has and you screw through that you have voided the warranty any way. You can fix it properly for a couple hours of time and less than 100$. Take a peak @ the Schluter manual Reg GWB is the bare minimum approved ASTM. When I took the Schluter contractor course, a # of us were surprised to see it approved, but it is and I cant argue with the engineer, what I can argue is good installer practices, and what provided the best bang for the buck to a client. The pros here will agree with me when I say the failure of Reg GWB and greenboard is so common, most building officials will not approve this type of install, and all of the GWB manufacturers stand fast on the fact of no warranty if installed in that type of condition. Keep in mind you are doing it yourself and are saving a great deal of money on labor so it makes excellent sense not to scrimp @ this critical stage. In the event of a plumbing failure regular GWB will absorb the water, turn to mush and allow the mold to thrive, which means replacement of the entire wall system, When if you had used a different method you open the GWB on the back side , dry the wall cavity out, treat for mold, repair the leak and you are good to go. I, by no means, am trying to discount your work or what you have been told. I am just trying to give the line to the best possible finished product you can get.
Trace