Installing sheetrock over concrete
I’m nearly finished adding an addition with a full basement to a house. As a result of this process, a formerly exterior concrete foundation wall has now become an interior wall in the enlarged basement.
The client wants this wall sheetrocked. At one level this seems easy: just fasten up strapping and sheetrock over it. At another level, I’m concerned about moisture. Although the concrete wall no longer has earth piled against it, nevertheless it still extends down into the earth.
Could the wall wick up enough moisture this way to be a problem? If so, is there an effective way to isolate the strapping and sheetrock from the moisture? For what it’s worth, we’re only sheetrocking one side of the concrete, so the other side will be able to dry into the house.
Many thanks, –Brian
Replies
Brian,
I'm assuming the old basement has a concrete floor & the addition will or does as well. We drywall in basements all the time so why not in the addition basement.
If you could post a pic maybe it would clear up something I'm not seeing in your question.
Paul
No one should regard themselve as "God's gift to man." But rather a mere man whos gifts are from God.
Water entry is most certainly a problem, even in the dryest location. You have two reliable solutions: plaster, and spacing.
Plaster directly applied to the concrete will let the moisture continue through .... or only limited, easily repaired areas will be damaged.
Spacing the rock off the wall is best, leaving small gaps at floor and ceiling. These gaps can be concealed with molding. The spacing will let moisture drain, or evaporate, before contacting the drywall.
The smallest spacing readily made is 1", using "hat channel." Far better is using at least 2x3" metal studs; this will give you room for the electrical and plumbing that will eventually be desired.
If you plan to insulate, I would apply the insulation directly to the wall, then add studs in front of it.
I would treat it like a regular foundation and not continue to wonder. That is, protect from moisture. I did my basement based on past articles and advises which is to install foam insulation panels directly to the wall, fasten strapping (I used cheap furring strips) over the panels with tapcon and use paperless or moisture protected sheetrock. Just to be sure, and again not wonder in the future, I used paperless sheetrock.
Furring strips may be a weak link. You could use metal studs which will give you more room for eletric lines. I decided to install the electric outside the sheetrock with wiremold. I didn't want to lose even half inch more because my basement is small. Hope this helps.
Use galvanized 1 1/2" metal studs. Place 1/2" channel in the slots mid height. Screw scrap piece of rock to side of every other stud back to concrete wall. I screw a larger than needed piece of rock and then cut off excess.The channel and the scrap rock stiffen the wall quite a bit,when the rock is screw on the wall will feel like a wood framed wall.
mike
Water shouldn't/can't penetrate the foundation wall any longer since wall is now an interior wall..thanks to addition. Only place for water source to find a way in is from the floor up. This really shouldn't be a problem unless you have had water/floor problems in the past.
With new addition and basement, drainage tile (French drains) should have been installed...if so, and done properly, no water should be able to penetrate and flow up through floor. If worried about joint connection between old foundation wall and floor, caulk this joint with butly caulk.
There is no real need at all to insulate the old foundation wall since this wall is now an interior wall. Suggestions Mike gave earlier about using metal studs and sheetrock stiffeners would work just fine. That's how it's normally done in my area too.
I personally hate using furring strips. I only go this route if space is a premium. Otherwise, you are always better framing up a stud wall approx. 1 inch in front of old wall. ( The finished new wall will project a total of 5 inches "out" from the original foundation wall) The 1 inch gap between old wall and new wall helps to avoid any framing problems that could crop up with irregularities in the old wall.
You can use metal studs, they are cheaper than wood, but if you feel more comfortable using wood studs, then go for it. I sometimes go for a hybrid route...I install treated 2x4s for my bottom plates. Then I attach metal "c" channel directly on top of the plates. I attach a metal "c" channel as a top plate, then come back and fill in between with studs. I use regular wood studs in place of the metal studs.
Instead of using drywall stiffeners, I shoot blocks of "L" shaped wood to the old wall in various locations and then attach these to the studs.
After this, I run any wiring or plumbing necessary, and then sheetrock overtop. Since this wall is not load bearing, it's not necessary to cut every stud to exact size when using this hybrid system. As long as the studs are long enough so you can "catch a screw" thru both bottom and top metal channels, you are good. This system makes it very easy to frame around and or under obstructions of any kind since you put this wall together one stick at a time. It's much easier than framing a wall on the ground, and then trying to raise it into position.
Metal studs do just as good a job, and works the same way, but I like working with wood whenever I can,,,IMHO it's easier to glue and screw drywall to wood studs than metal...it's easier to cut them too.
If worried about mold/mildew, use the new mold proof drywall.
Good luck on your project.
Davo
Thanks everyone for your ideas. I had thought of treating the situation like a regular basement drywall job, where I would install rigid foam over the concrete and then strap. This would give me the moisture barrier I need --- but also insulation which I don't. Hence my search for alternatives. Thinking through the details of my situation I think the plaster or the spacing option are ideas especially worth my consideration.
Thanks again to all, --Brian