Drywall Repairs to Large Holes (3″ and larger)

Off the Top of My Head:
Some thoughts regarding planning ahead when you do your own painting projects:

  1. Buy enough paint so that you have a minimum of a quart left over for future touch up, unforeseen repairs, etc.
  2. Record the paint brand name, color name and # and the color formula if it is a custom mixed color to keep in your Home files.
  3. Store paint in a place that will not be subjected to sub freezing temperatures.

Speaking of planning ahead………on my last blog I had stated my intent to cover the topic of drywall texturing in this blog entry. Being a student at “A Picture is worth a Thousand Words” University, I knew that a photo of the different textures would be a requirement for this assignment. Don’t have the photos yet. Since my previous blog topic was about repairing small holes in drywall, my innate sense of logic and form leads me to conclude that the appropriate sequel to that  blog is:

Drywall Repairs to Large Holes – 3” and larger

Tools needed:

- measuring tape
- utility knife
- 6” wallboard saw
- power reciprocating saw “sawzall”  (optional)
- framing square  (optional)
- drill/screw gun
- 12” drywall pan
- 4” drywall knife
- 6” drywall knife
- 12” drywall knife

Materials needed:

- 1×4 or other backing material
- piece of wallboard/drywall
- 1-1/4″ drywall screws
- self adhesive mesh joint tape
- all purpose drywall compound or dry mix quick dry joint compound
- topping finish drywall compound
- sanding sponge or 120 grit sandpaper

Repair instructions:

STEP 1. The first thing you will need to do is prepare the damaged area for repair. This can require several steps depending on the nature of the drywall damage, e.g. water pipe leak, impact hole, etc.

- If you are cutting out an area that is water damaged, determine how far the damage extends in compromising the structural integrity of the drywall. You may have water stains that extend far beyond the actual drywall that has been damaged to the point of needing replacement. Most likely, the worst damage will be obvious to your eye. The areas around the core of the damage may be less so. One test to determine the viability of the drywall is to put a nail into the drywall. If you can push the nail through the drywall with your hand or it crumbles with the pressure from the nail, it needs to be replaced. Conversely, the presence of water stains does not automatically indicate that the drywall must be cut out.

NOTE: Water stains will need to be covered by a primer/ stain sealer to prevent the stain from “bleeding” through the joint compound you will be applying to that area. Kilz and Zinsser are two common brands that come in aerosol cans and are available at all building supply stores.

STEP 2. After determining how much drywall is to be replaced, you need to cut out the area to be repaired to a rectangle or square. If the hole is already there, e.g. a plumber has repaired a pipe, it needs to be reshaped to become a rectangle or square. This can be accomplished by measuring and marking parallel lines in pencil at the outer edges of the repair area. Using a 6” wallboard saw or sawzall, cut out the drywall along the pencil lines.

NOTE: Most DIYers I encounter are under the impression that any repair area has to be expanded to the closest stud or joist. Not necessary…..the  installation of “backing” negates this. This is covered in step #3.

Do not use a pen to mark your lines. Ink bleeds through drywall mud and paint. If you inadvertently use a pen, apply stain sealer over the pen markings.

I only use the wallboard saw. It takes longer to make the cuts manually, but the hand saw is not as aggressive as the sawzall and will indicate when I have encountered obstacles inside the wall – electrical wires and pipes. The sawzall will cut right through these before you know you have hit them.

STEP 3. The next step is to install “backing” along 2 parallel sides of the hole you have just cut. This will act as a splice for anchoring the edges of the new drywall piece and the  existing drywall. This backing material can be a 1×4, 1×6 2×4, MDF board, etc.

For example, if you have cut out a repair area that is 12”x 12” between two studs, you will install 2 pieces of backing along two parallel sides of the  hole. Cut 2 pieces of backer material approx. 2-3” longer than the length of the hole you are going to cover. In this  instance, 14-15”.

Using the 1¼” drywall screws and your screw gun, install screws approx. 1” back from the edge of the hole into the existing drywall on parallel sides of the hole. Install a screw approx. every 4” and temporarily sink the screws to the depth of the drywall – ½”.

Insert your backer piece through the repair hole and hold the flat side of the backer up against the back of the existing drywall with the partially sunk screws. Position the backer board so that approx. half the width of the board is behind the existing drywall and half extends into the hole that will be covered with new drywall. Holding the backer board firmly against the back of the drywall, finish sinking the screws through the drywall and into the backer until the backer board is firm against the back of the drywall. Make sure you slightly countersink  (screw head flush or below surface) the screws in the drywall.

NOTE: Ideally, you do not want to countersink the screws until the head breaks through the paper covering of the drywall. If you sink the screws too far, they will fail to anchor the backing. The easiest way to insure a perfect countersink is to use a drywall installation phillips head fitting for your drill. These can be purchased for a couple bucks in the tool department.

Even if the area you are repairing is large enough to span one or more studs or joists, you may need to add backing along the hole edges that are parallel to the studs/joists. A rule of thumb to follow: if the repair hole extends less than 3” past the outer edge of a stud/joist you do not need to use backing. The proximity of the stud/joist will provide sufficient rigidity to negate the need for a backer board. This is referred to as a “floating joint”. If the repair hole extends more than 3” past the outer edge of the stud/joist a backer board is required.

STEP 4. Cut a piece of drywall to fit into your repair hole. Size the piece to be approx. 1/8” smaller than the opening. Using our example of a 12”x12” hole, the dimensions would be 11 7/8”x 11 7/8”.

NOTE: A few tips if you have never worked with drywall before:

- Drywall comes in 4’x8’ sheets which can mean a lot of wasted material if you are patching a relatively small area. Home Depot carries 2’x2’ pieces of ½” drywall.

- “Score” the front side of the drywall with the utility knife. Use a  straight edge, e.g. a board to get a straight cut. Unfortunately, you must score the drywall from edge to edge in order for it to break along your score line.

- Apply hand pressure to both sides of the “score” on the front of   the drywall to “snap” the piece along the “score” line. Use your utility knife to cut the crease on the back of the drywall.

STEP 5. Fit the piece of drywall into the repair hole. Install drywall screws along the 2 edges that will cover the backer board. Space the screws approx. 4” apart. Set the screws into the backer board until they are flush or below the surface of the drywall.

NOTE: If the repair area spans one or more studs or joists, also countersink drywall screws into the studs/joists spaced approx. 6” – 8” apart.

STEP 6. Cover all the joints where the new and old drywall meet with the self adhesive joint tape mesh. This mesh tape comes in rolls, so start approx. 1½” past one corner and roll joint tape out so that the seam of the drywall is close to the centerline of the tape. Cut the mesh tape with the utility knife. Use the flat edge of the 4” drywall knife to insure that the joint tape is lying flat and adhering to the surface of the drywall. This will present problems when you are applying the joint compound if there are folds or loose spots in the tape.

TIP: Since the joint tape is self adhesive, when I cut the tape I fold the roll end of the tape under itself so that I won’t lose the end of the tape. I then cut off the folded piece when I am ready to roll out more of the mesh tape. You will see the advantage of this the first time you forget to do this and can’t locate the end of your tape roll.

STEP 7. Apply a coat of joint compound with the 6” drywall knife to cover all of the joint tape. Using the flat edge of the knife pull the compound over the joint. Go back over the joint several times so that you have a thin, smooth coating of mud and the edges of your mud line are flush with the wall board surface.

NOTE: The first coat will take 3-5 hours to dry depending on humidity,  mud thickness, etc. You can use quick drying muds to speed up the process. These come in drying times that vary from 5 minutes to 90 minutes. They are in powder form that has to be mixed with water immediately before application and are in the drywall supply section of the home supply stores.

STEP 8. After the first cost of joint compound is dry, apply a second coat using the 12” drywall knife. You want to extend the second coat of mud past the outer lines of the first coat to obtain a smooth finished edge.

STEP 9. Apply a finish coat of mud with the 12“ knife “feathering” out the edges of the repair area even further to get a smooth finish. You can use All Purpose joint compound for this coat, but for the best results I use “topping” compound. This is available with the other drywall compounds at the home improvement store.

STEP 10. Lightly sand the repair area with 120 grit sandpaper or a drywall sanding block to remove any high spots, ridges, grooves, etc.

NOTE: Be particularly careful when sanding over the joint tape mesh. It is very easy to oversand and expose the mesh. This will be hard to cover if you are not finishing with very heavy texture.

STEP 11. You are now ready for the final step – texturing. The topic of texturing will require several blogs to cover, so stay tuned.

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