Tapering Drywall

[Meanie]

Most of us who have hanged drywall at some time in our lives are well aware the long side is tapered for mudding. There are time when two non-tapered edges will meet or one tapered and one non-tapered edge with meet. I will be in a predicament which will put the tapered edge of 1/2" drywall along a length of existing painted non-tapered wall. Is there a method and/or tool used to taper a non-tapered drywall/wall edge?

Thanks

[Mike Paulsen]

1. Wash the painted wall with wall cleaner (TSP or substitute).

1. Use a sharp utility knife to clean up the edge of the painted wall so there's nothing loose.

2. Sand the painted wall, wipe clean, and then prime. You want the mud to stick, and priming is going to give you a good chance of that happening.

1. Hang the new rock.

2. Prefill the joint.*

1. Tape like a butt joint.

• You are going to end up having to treat this as a butt joint anyway, so you might as well prefill before you tape. Basically, you want to fill in the tapered edge so it is at the same level as the painted wall. Don't build up any mud on the painted wall at this point, of course. After the prefill is dry and you've scraped off any ridges or bumps, tape as you would a normal butt joint.

If you try to apply tape without prefilling (and letting it dry) you need a certain amount of experience and touch to leave the right amount of mud under the tape on the high side while getting the tape embedded in the tapered side. Novices always seem to end up with with bubbled tape when they try.

[Cliff H]

The only way to taper it is to sand or grind a taper on it. That woud remove the paper and weaken the wall. So can't be done. You could bevel the edge a bit just to keep it from telegrphing though.

[Meanie]

...but why would I need to wash the painted wall if I will be sanding the painted wall?

[Mike Paulsen]

I wouldn't count on a light sanding to clean most walls. It also roughs up the paint a bit for better adhesion. If I had to do one or the other, I'd wash.

[HerHusband]

I have seen a method that uses blocking (such as a piece of plywood with strips of wood on each side) on the back side of the wall, to force the edges of the sheets to bend inward slightly when you screw it down. Obviously, this would only work if the joint lands between studs, and I would be worried about screws popping through as the drywall tries to resist the bend. It's also not an option if you're meeting drywall with old plaster and lath.

For me it's not worth the trouble, as most butt joints can be taped and tapered to virtually disappear. Unless you stick a straight edge on the wall, you would never know there was a bulge.

If you need a really straight wall for mounting cabinets or something, you can usually position the joints above or below the cabinets so the "bulge" doesn't end up behind the cabinets. Of course, most walls aren't straight anyway as the studs warp and vary in thickness slightly. Shimming behind cabinets is a normal part of installation.

Good luck,

Anthony

[trader4]

Which should not happen if the drywall is hung correctly. You want the joints over studs, not between them.

[Mike Paulsen]

Not necessarily. I haven't heard many complaints about buttboard (or DIY versions of the same basic idea).