8

I need to fix a hole that is about 12x16. I am cutting it to the studs and plan to attach both sides of new piece to a stud. I am capable, but there is a lot of info out there.

  • Nails or screws?
  • Do I really need a special drywall screw gun?
  • I cannot understand the lingo on the mud.
  • If I get three trowels, what are the best 3 lengths?

Can someone explain this to me like I am 5 years old?

  • 2
    If you've never done drywall work before, or have never seen it done, watch a few YouTube videos before trying it yourself. – Tester101 May 19 '15 at 2:03
9

It's a patch - you don't need a special screwgun, you don't need ANY screwgun.

Use screws - nailing drywall is an art form and takes a special hammer. Screwing is easy and takes a Phillips screwdriver. If you use a "not special drywall screwgun" stop before the screws are all the way in and use a screwdriver to finish. The head of the screw should end up just below the surface, but not so far that the paper breaks. Practice a couple on scrap - start with going too far and then you know what not to do - get a couple just right before you start on non-scrap. Backing up after you go too far does not work - the strength is gone when the paper breaks. If your shortest knife run across the surface does not hit the screwhead, it's deep enough.

You don't really need 3 knives/trowels (knife, ala puttyknife, is more common in this context) for a patch, either, though they are nice to have when doing a whole room (same applies to the screwguns, which can be rented when you have a whole room to do.) A big one (12") and a small one (3-4") should be sufficient, but if you want to be over-equipped for this job or equipped for the next one, add an 8". Try a yardsale if you can find one, if cost is an object.

Mud lingo - don't get too concerned, it's a patch, you want standard mud that you can get in a small (4 lb or so) tub. There's rarely a choice in that size. Since you don't say what mud lingo you don't get, I'll go into a few - hot mud is dry powder you mix with water that sets quickly (the number of minutes it's supposed to be workable are usually in the name.) Standard mud comes as a paste in a tub or bucket, and dries rather than sets. Lightweight mud is like standard mud, but lighter (almost foamy.) All "mud" is actually labelled as "joint compound" but pretty much universally referred to as "mud"

The secret to mudding is to get it on good enough and stop, let it dry, and then put on the next coat. Trying to make the first coat "perfect" usually makes it worse than if you stopped 20 minutes earlier. It will shrink when it dries anyway - the multiple coats of mud serve to fill smaller and smaller defects, so there's less fresh mud, so it shrinks less each time.

  • 5
    Good advice above. My only addition is to say that less is more. In other words, lots of thin coats is better than a couple of thick coats. You'll sand less, and avoid the dreaded drywall dust that gets on everything. My preference is to use mesh tape (not paper), and for a little patch like this, I'd use a 4" and a 5" knife. – Aloysius Defenestrate May 19 '15 at 1:17
  • 1
    @AloysiusDefenestrate Paper tape is thinner, and so is easier to cover (especially for patches where you're not likely working with tapered joints). While it's not self adhesive, it's easy enough to apply. – Tester101 May 19 '15 at 1:58
  • @tester101, agreed on all points. My problem with paper is either putting too little or too much under it. Mesh has none of these issues. – Aloysius Defenestrate May 19 '15 at 2:38
  • If you are only patching a small area, you can get a special drywall bit for a standard drill/driver which will cam out when the screw head gets to the proper depth. It takes a bit of practice, but it may help you out. The bit costs a few dollars, and the drywall gun is probably around $75-85. The trick is to get the screw deep enough where it won't catch the edge of the trowel, but shallow enough that it doesn't tear through the paper on the drywall. The proper depth below the surface should be somewhere between 1/32" and 1/16". – Jason Hutchinson May 19 '15 at 20:17
5

I'm assuming a flat wall (not textured).

Use screws. Make sure they are black drywall screws. Make sure all the screw heads are below the surface of the drywall (Ideally, they should dent the drywall, but not punch through the paper.). Any driver will work, even a hand screwdriver. You don't need three trowel sizes. You can make do with the 6- or 8-inch drywall knife (not actually a trowel) if you don't mind doing a little sanding. Use scraps of plywood behind all the joints and screw to the plywood through the existing wall as well as your patch piece. Cut the hole rectangular so that you cut a rectangular patch. It's OK to have a bit of a gap between the patch and the wall (1/4-in or so). Lightly sand the painted wall so the mud sticks to it. I would use pre-mixed "Topping Joint Compound" mud for all coats. Mixing it yourself is a pain. The "lightweight" stuff is cheaper, but will cause little voids to open up when the paint dries. Topping compound takes a little longer to dry and will shrink more so it's not as good for filling gaps. Plan on feathering mud and re-painting a portion of wall much larger than the patch (3ft x 3ft in your case). Trim away any loose bits of drywall paper or push them into the gap. You don't want anything that will cause a bump. Apply thin coats, let dry thoroughly, sand off ridges and apply again. Someone with experience would probably do two coats. A shy beginner might end up doing 4 or 5. Keep your bucket of mud clean and don't let it dry out and don't put leftover mud back into the bucket. There is nothing more infuriating than a little chunk of dry mud leaving marks on your skim coat. I would consider drywall tape optional for a patch this size, however others may disagree. I find that you have to build up too much to cover the tape and you end up with a visible bulge. Put wood glue on the plywood scraps if you want some insurance against cracks where the joints are. I would apply primer before the painting the finish coat. You can do another skim coat of mud over the primer if some imperfections jump out after priming. Just prime again, and then use a roller for the finish coat of paint.

This video should help. http://www.thisoldhouse.com/toh/video/0,,20052318,00.html Kevin is only slightly older than 5.

There are lots of different ways to patch drywall and no real right way. I think it has less to do with the technique and more to do with experience with whatever technique works for you.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.