Mild water damage on drywall from leaky roof

Question

We have a fairly new house (built in 1997). Cheap roof and we had a big windstorm a few years back that resulted in some lost shingles that I had patched -- no major problems. Recently we had a much more mild windstorm that stripped off some more shingles. I was lazy, didn't check the roof for about a week or two and I noticed some water damage on walls. I went up on the roof, found a missing patch (that was clearly leaking) and patched it.

The damage is basically just a darkening along the top edge of the wall along 3 walls in the house. It's not immediately noticeable but it's fairly obvious upon close inspection. The areas around screw heads are darker and the screw heads themselves are in a few places slightly bulging.

What's more concerning to me is that some walls (and some ceiling joints) have become very visible. There's no obvious sagging or bulging, it just looks as if it was painted and someone someone didn't tape the joints at all. I don't know if this is normal water damage...

Because of the type of damage, it took me a while to notice much of it. Although I don't see any sections getting worse, I'm concerned that the leak may not be resolved.

Two questions:

1. Assuming that the leak is stopped, is this sort of damage something that I can simply prime over and repaint (and in the case of the joints and the screw heads, just add a little joint compound to level things out). Or should I be cutting stuff out and replacing entirely? The perfectionist in me wants to replace everything, but this is going to cost a lot...

2. Are there are tips or tricks that I can take advantage of to test whether I do in fact have any additional leaking? I feel kind of stupid asking, but it's a real pain to crawl around in the attic trying to feel for dampness when it's a bit damp everywhere (we live in the Pacific Northwest). What should I be looking for to identify "chronic" leaks? I hate to wait until additional damage is apparent in the walls and would like some "assurances" if possible. There are what appear to be discolored rafters in the attic, but I'm assuming that that's from previous water damage -- not ongoing leaking.

Answer 1

A few additions to Jeff's advice if you decide to replace the damaged drywall.

1. I'd suggest you look into waterproof drywall or mold resistant drywall. There are various products that do a better job than the typical green board that you would use in the bathroom that will help if you are installing in an area that has a lot of exposure to the elements.

2. Double check the thickness of your drywall if you are patching. If you replace a 5/8" with 1/2", you'll notice it.

3. Use screws, especially on the ceiling. They take more time, but hold better and are less likely to cause the nail pops that you are seeing.

That being said, I think it's entirely possible that you're just more aware of drywall issues and there may not be anything wrong. To know for sure, I'd go up to the attic, pull up the insulation where you suspect damage, and look for water rings or other mold growth. Use a flashlight, no need to feel with your hands (and risk falling through). While you're there, check the insulation for blackening that would indicate mold is growing there, and if so, replace any damaged pieces.

Your ability to see the joints between the drywall is just a sign of not enough paint and/or primer. And popped nail heads are normal as a home moves. My personal plan is to replace all the popped nails with screws and double up on the spacing the next time I paint to minimize this issue.

Answer 2

1. make sure that you isolate all the damaged areas, dont miss any of them. (damaged coloring)

2. cut out the damaged areas and use a dehumidifier and large fan to dry get the moisture out of the remaining

3. if you still notice moisture after a day, you will probably want to remove more of the dry wall - mold can end up developing

4. Replace the drywall once everything dries out by re-installing any studs that may have been compromised and placing a new drywall patch over the hole. If the hole is very large, first install a plywood backer board onto the studs that will hold the new drywall in place.

5. Nail in your drywall patch (preferably a water-resistant type) to the backer board and then spread joint compound over the edges using a putty knife. Sand down any depressions that appear. If the leak occurred near the floor, leave a small clearance between the drywall and the floor to protect your wall in case of another leak.

6. Tape off the joint where the drywall meets the existing wall using drywall tape that can be purchased at your local hardware store. Once you have a smooth finish, you can paint the new drywall to match everything else.

Answer 3

I think Jeff is technically correct. The best way to do it is to cut all of the affected areas out and replace it.

However, I would just take my 6" drywall knife (get a nice metal one), and scrape out anything that is bulging. If you run your fingers lightly over the area, you will hear any spot that has air underneath it, and that needs to come out. If you can hear it, but the six inch knife does not catch it, then you should use your utility knife.

Then level it out with joint compound, sand and paint. I have done this with quite a few spots, (I have kids that like to overflow the second floor tub and toilet) without the spots reappearing.

The other answers were correct about mold. That can be a very serious issue. You will need to make sure that there is no mold in the attic. If there is you will have to remove bigger chunks of the drywall. It is not that expensive tho, and really easy.