Hello,

Soon I will be replacing the fire-rated sheetrock on the wall of my garage that is adjacent to the house. I want to be sure that moisture doesn't destroy the sheetrock again.

If interested you can see
pictures of deteriorated sheetrock

In winter, snow and frozen slush from our car melts when the car is parked in the garage. That water pools right up against the wall.

What I am considering doing is installing a PVC baseboard and sealing the bottom edge with a silicon caulk. My concern, however, is that moisture will continue to be wicked up by the bottom plate. Then, that moisture would be trapped behind the PVC baseboard--which would likely rot the bottom plate and encourage mold growth.

I can't afford to have the garage floor re-pitched to correct the root cause of the problem (i.e., the floor slanting toward the house instead of away), so what can I do to improve the situation and not cause problems down the road?

Thanks in advance.

You might look into the paperless moisture resistent drywall. I believe that it is also fire rated. You can see if this would work better. http://www.gp.com/build/densar...rmance-gypsum-panels

You might also try using a completely waterproof material as a base to set the drywall on raising it off the floor to where the drywall will not wick water.

This message has been edited. Last edited by: redoverfarm,

You have the right idea, but there's a couple of things that would make it better.
If I had to do this job I first figure out if the drywall was installed vertical or horizontal.
If your lucky it was horizontal.
If it was then cut the along the tape line and remove just the bottom part of the drywall. (an ossilatiing saw works great for doing this) Remove the tape on the upper part and clean it up.
For the next part in order to make sure the base looks level you measure how long your pieces of PVC 5/4 (do not use 3/4" thick PVC) 1 X 6's are and make a mark on the floor starting at the front of the garage. Now measure from the ceiling down to the floor at both ends where the marks are. Subtract the to readings, that gives you the amount that needs to be removed from the base so the top will sit level.
Most garages have a sloped floor by code so water or gasoline will run out the door.
Apply silcone on the floor and on the bottom plate and install the PVC tight to the studs With galvinized finish nails.
Now install Z moulding on top of the base. Once you have cut and test fitted the drywall apply another layer of silicone to the Z moulding then install the drywall.
By sitting the drywall on top of the PVC you will be 100% sure the drywalls not going to be rotting behind it. The added Z moulding and silicone keep the garage air tite so there's no fumes getting into the house.

Thanks for your ideas redoverfarm and joecaption.

Joe, I really like what you described about using the 5/4 PVC. I'd be concerned, however, that, with no fire-rated drywall behind the PVC that it won't meet code (I'm putting in a fire-rated access panel into the attic crawlspace from the garage, so I need to get a permit, which means there will be an inspection).

Thanks again.

I see your point, it would do no harm to run it by the building department.
It still would be air tite if done right. Heat rises last time I checked so I'm not picturing it catching on fire and melting.
An alterative would be to add 2 X 4 blocking in each bay at the bottom of the wall so you could have the sheetrock 1-1/2 off the floor and still be able to attach it to the wall. Then add the PVC like a reguler Base board.

run sheet metal like aluminum sheet under the PVC and over the drywall? that ought to satisfy the fire blocking. you could also squirt in and trowel smooth fireblock silicone caulk.

What about a different material, like those panels that people use in their bathroom instead of tiling their walls. I think that would stand up better than drywall in such a moist environment. Just a random thought...