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DIY Drywall Repair

drywall, Wall Coverings, walls March 28, 2007 Sonia

Here’s something that happens in remodeling projects all the time: You (or the electrician) installs a light fixture or receptacle in the wrong location. It’s easy enough to get him to move it, but having an electrician repair drywall is like getting a demolition laborer to cut dovetail joints—it ain’t gonna happen. So that leaves you with a light switch in the right place and a hole in the wrong one.

The good news is that with a little Dura-Bond 20 or other fast-setting, site-mixed compound (see sidebar pg. 24), you can make a seamless repair that you can complete in about half a day. The other good news is that this technique is also great for patching other holes: Like when “Sheeter Dave” gouges the wall hauling plywood through the house.

But these techniques aren’t just for the jobsite. They’re also terrific for making repairs in drywall—or plaster for that matter—from other damage, like a wall gouged during a furniture moving fiasco (moving furniture is always a fiasco!), your teenager’s wrestling match, or from breaking the age-old Mom-rule: no playing ball in the house! Soundproofing Products for the Home

The tricks laid out below are called the Bullet Patch and Batten Patch respectively. They minimize the size of the patch and don’t require you to peel drywall back to existing studs for fastening purposes.

The bullet patch (so-called, because you can do it pretty darn fast, or at least that’s what I’m told) is smart and easy. It works great for holes around the size of a two-gang light switch, but can be used for bigger or smaller repairs too. The batten patch (that’s what I call it due to the “batten backers” inserted behind the existing drywall) is often best suited to larger repairs and ceiling repairs. It offers more stability while the compound sets up, but requires a little more trowel trickery with taping and sanding.


Bullet Patch

The bullet patch is such an ingenious and time saving idea that whoever thought of it should be given some sort of Lifetime Achievement Award. My guess is that this is the kind of site-borne invention that clever carpenters, drywallers and painters devised individually until the word spread and it became part of many tradesmen’s bag of tricks.

The key to is to cut a blank of drywall bigger than the hole, then on the back of the blank, expose a “plug” of drywall just a bit smaller than the hole. You do this with a series of clever cuts and breaks. What’s great about this is that while you remove the oversized portion of the drywall, you leave the paper—which acts as tape when you mud it. It’s as seamless as seamless gets.

Clean Cut: The first step in the bullet patch process is to clean out and square the hole. This is done in the case shown here, where the repair is being made because of an errantly placed switch box. But, if the hole is made by a fist, hammer, or some other blunt force, then use a drywall saw to remove the broken or damaged drywall (or plaster and lath) to make it rectangular in shape.

Next, if there are any obstructions or finishes near the patch location (like a light switch cover), remove what you can. If the finish can’t be removed (like wallpaper or molding) protect it as necessary with blue painter’s tape.

Measure and Cut the Repair Piece: Once the hole is squared out, measure it. Now, go to your new drywall and cut a piece that is 2 inches bigger than the hole’s measurement all the way around. For example: Say that the hole turns out to be 4 inches by 4 inches; cut a new piece of drywall 8 inches by 8 inches.

Now, flip the blank over so the front is face down on your work bench and the back is face up (the brown side of the drywall is the back). Use a tape measure to locate the center of the blank. Mark it. Note: It’s easiest to mark the drywall by cutting slits with your utility knife rather than marking with a pencil.

From the center point, map out the plug. Make the plug about 1/4 inch smaller than the hole’s dimensions all the way around. For example, if the hole is 4 inches by 4 inches, make the plug 3-3/4 inches by 3-3/4 inches. The easiest way to mark both edges of the plug is to hold the center point of the measurement—1-7/8 inches in this case—aligned with the center point lines on the drywall. Mark both edges of the tape and in two locations. Use a straight edge (a scrap of 1-by works fine) and connect the dots by cutting with your utility knife.

Cut and Break: With your lines mapped out on the back of the drywall in a grid pattern, cut them with a utility knife. Grasp the drywall firmly in both hands and break it along one line. Then—and this is the cool part of this process—carefully peel the gypsum (the white chalky material) away from the paper. Discard the gypsum and leave the paper flange. Do this all the way around the piece until you have exposed the center plug.

Note: it is much easier to use a piece of drywall that is not from the factory edge of a piece of wallboard because of the way the paper folds over at that location—or because ends are usually banged-up, cracked, or have labels you have to deal with. Use a piece cut from somewhere inside the factory edge of the wallboard for better results.


Applying Mud

With all finished surfaces masked as necessary, apply a thin coat of mud (skim coat) to the wall before installing the bullet patch. Don’t wipe it down tight. You need enough mud on there so you can embed the back of the paper flanges into it.

Next, put the patch on the wall and lightly press the paper into the wet compound with your fingertips (don’t press on the plug) this usually holds it in place. Now, put a little compound on the edge of your knife. I use a 6-inch knife for this job. The mud “lubricates” the knife edge and enables it to ride across the paper. Take the knife and press hard enough on the patch to squeeze the mud out from behind the paper. Be careful not to press too hard or you risk “oil-canning” or rippling the paper. A couple of passes ensures a tight bond.

Now, with the paper adhered from the back, wipe a feather-coat on the front of the paper. You only need a light coat. Smooth down all rough spots—but don’t expect perfection. A thin light coat that bonds the paper to the wallboard is the key here. A cool trick is to flare your knife. (See “Flare Up” sidebar).

Second Coat: Once the first coat has dried you can apply a second coat. While an ace, like my painter Bobby Ann of Sister’s Painting in Ambler, Pennsylvania, can do it all with a 6-inch knife, it’s sometimes easier the first time out to use a 10-inch knife on the second coat.

First, take a 10-inch knife with no compound on it to lightly scrape down the area, knocking off any crunchy high spots. Second, use the 10-inch knife with compound. The goal again is not perfection, but to fill in more imperfections.

Third Coat: These repairs usually take three coats. Apply a third coat. With two coats on, hit the repair with a 100-grit sanding block to help smooth things out. Sand lightly. And, you don’t always need to use a larger knife here (as you would with a regular drywall job) because these are usually smaller patches. Fill in and feather out the edges with the third coat.

Vacuu-Sponge the Dustless Drywall

Sanding: Sand as necessary to flatten the field and feather the edges. Remember that sanding setting-compound is much tougher than sanding evaporative-type compound, so it’s easier to add a fourth coat than to sand off three thick ones. Less is more here. Once sanded, you’re ready to prime and paint.

Batten Patch

The batten patch is great for making larger repairs or for working on the ceiling, where gravity tugs at the repair before the mud sets up. Note: Bullet patches work on the ceiling (say you cut in a recessed light in the wrong location), but they’re a little trickier to work on.

For the batten patch, you’ll not only need drywall and setting compound, but you’ll need drywall tape, a cordless drill/driver, screws and probably a wood-cutting saw.

Square Deal: As with the bullet patch, square up the hole as necessary using a drywall saw.

Batten Backers: The key to this system is to install battens behind the drywall, as fastening backers. I typically use some thin strips of 1-by or rip some 2-by on the table saw, but Sister’s uses sections of the thick paint sticks (like you’d get for mixing a 5-gallon bucket of paint). Don’t use thin paint sticks; there’s not enough meat to get a good hold, and they split.

Let’s use the example dimensions of a 4-by-4-inch hole again. Cut the two batten backers so they’re at least 2 inches larger than the hole, so cut them 8 inches long in this case.

Load up your cordless driver with a drywall screw and leave it where you can reach it. Then, work a batten backer into the hole. Hang on to it so it doesn’t fall down into the stud bay; grab your drill. Pop a screw into the batten through the wallboard. Remember that as the screw hits the wood it pushes the wood away. Oppose the force by keeping a firm grip on the batten. Repeat the process with the second batten. Tip: Set drywall screws so the head just dimples the surface of the paper. That’s how to get the best holding power.

Install The Wall: Measure, cut and install the repair drywall piece. Again, it’s easier to use a piece that’s not a factory edge because sections from the “field” of the drywall (aka, anything that’s not the factory edge) are flat. Cut the repair piece just a little smaller than the hole. If necessary, use a rasp to tune in the cut. It’s best if these plugs fit close. Fasten with screws.

Tape and Mud: Tape and mud the hole as you would for new drywall installations. Sister’s likes the nylon mesh tape here because it adheres to the wall and can be finished well, but I prefer paper tape. I like paper tape because it lays flatter and I can finish it better.

Whatever you choose, mud, tape and sand, as with the bullet patch. Prime, paint, then show off to your friends what a drywall repair ace you are. And then you can use the old jobsite phrase pro’s use to sing their own praises—“See that! It looks like it grew there.”


Mix Up Some Mud

Site-mixed—often called “setting compound”—dries chemically like concrete rather than by evaporation, like compound you get in a bucket. I typically use Dura-Bond 20 for bullet and batten patches because it dries so fast. “20” indicates the approximate number of minutes it takes the material to dry. Dura-Bond also comes in 45- and 90-minute formulations. I usually use 45 for paint prep or even taping whole drywall jobs so I can get the first coat on fast then follow up with a second coat of evaporative compound.

I like to mix the Dura-Bond in a 2-gallon plastic bucket with the flattest bottom I can find. I use a plastic cooking spoon to scoop the powder out of the bag and a metal margin trowel to mix it up in the bucket. The goal is to get the balance-of-powder-and-water such that the resulting material is pasty. It should stick to your drywall knife for a few seconds before beginning to slide off.

Here’s a mixing tip: Pour 1/2 inch of water into the bottom of the bucket. Put in a couple of spoonfuls of powder. Let the powder absorb the water for five minutes and it’ll be easier to mix. And remember, you want the mix like Stove Top Stuffing—no lumps. Note: I’ve tried using a small mixing paddle on my cordless drill to mix this compound and almost always get better results hand-mixing.

A little mix goes a long way, and this is a small patch. Getting the water-to-powder ratio right takes some trial and error, but the stuff is cheap so practice is easy.

After you’ve mixed the mud and applied a coat to the wall patch, make sure to throw out the mud left in the bucket right away—for a couple of reasons. First, it’s easier to scoop out the mud before it dries to the consistency of concrete. And second, using a clean bucket for every batch keeps the material from setting up quicker than it’s supposed to. I use a grout sponge and water to wipe down the margin trowel, knife and bucket after every batch. It seems like a pain, but believe me, it actually saves you time—big time.

Flare Up

One trick to minimizing sanding and getting a tight finish with joint compound—as quickly as possible—is to learn how to flare the knife blade as you wipe on the compound. It’s all in how you apply pressure to the knife blade as you apply the mud.

The first step in taping or bullet patching is to embed the paper surface in the compound and wipe it down flat. I do this by first applying pressure evenly across the knife blade. Once I’ve squeezed all of the compound out and the paper is essentially flat on the wall board, then I “feather” the edge.

Here’s how: Along the perimeter of the joint compound apply more pressure to the outside of the knife than the inside, slightly bending the knife blade. This tapers—or feathers—the outside edge of the mud and helps deliver a nice crisp finish that requires less sanding to blend with the surrounding surface.