When a large section of drywall ceiling is saggy, warped, droopy, broken, moldy, or wet, you need more than just a spot repair. Sometimes the problem extends so far that it's best to remove an entire 4-by-8-foot drywall panel, or at least a large section of it, and replace it with a new panel of the same size. A few pro tips can help the job go more smoothly.
Be sure that the problem that caused the damage is fixed before replacing the drywall. Usually, sagging, warped, moldy or wet drywall is from some source of moisture. If there is an attic above the damage, there is probably a problem with the roofing system. If the damage is below an upper floor, the problem is usually plumbing related.
- New drywall panel
- Nailing strips
Clear Out the Attic Insulation
If the damaged ceiling is below an attic, chances are the attic has insulation. You also have an access door that leads up to the attic. Look for the door in a coat closet or bedroom closet, or even in a hallway or utility room. Put a ladder up to the door, push the door open, and set it aside.
Hopefully, your insulation consists of strips (short "batts" or longer "blankets") of fiberglass insulation or possibly cellulose insulation, as this form of insulation is the easiest to move.
Don gloves, a long-sleeved shirt, and a mask, and set up a work light in the attic. Move the batts to the side. You only need to remove insulation from the area that will be repaired—not from the entire attic.
Remove the Old Drywall
With the area clear, you can see the perimeter of the drywall to be removed. Also, make sure there are no wires or pipes in the areas where you will cut out the old drywall. The edges of the drywall will be attached to ceiling joists, although you may encounter some hanging edges supported by a strip of drywall that bridges to the adjoining sheet. Take note of these hanging edges because they will not be picked up by the stud finder.
Below the ceiling, identify places where the drywall is attached to joists by using a stud finder. Outline your planned "cut edges" with painter's tape.
Removing drywall without damaging adjacent areas is difficult, and there is no one way to go about it. Follow these suggestions:
- From below, punch into the center of the drywall with a drywall saw or reciprocating saw and slice away strips until you meet a stud. Then, pull the strips down by hand.
- If you are removing a section with an edge that hits the bottom of a joist, you can pull straight downward. It will separate from the adjacent section of drywall at the joint. After the joint compound breaks away, cut through the embedded tape with a utility knife.
- If the section of drywall bridges a joist, but you only want one side of the drywall removed, cut with your saw alongside the joist. Be sure to cut the inner portion so that the adjacent section of drywall is still fastened to the joist. Shown here, the section of drywall that remains is on the right; the portion to be removed is on the left.
Add Nailing Strips
All the old drywall is gone. But you've got a bit of an obstacle. In some instances, you will have no exposed joists on which to nail your new sheet of drywall. The edge of your drywall can't just hang out in mid-air; it has to be attached to something.
The solution is to add nailing strips of 1x3, 2x2, or 2x4 lumber to the sides of the joists where the new drywall needs backing. The drywall will be screwed to the nailing strips.
Position each strip so it is flush with the bottom of the joist, and fasten the strip with screws driven through the strip and into the joist. If there is any deviation, the new drywall panel will not be level with the surrounding panels, and no amount of finishing will fix it.
Install the New Drywall Panel
Buy new drywall that matches the thickness of the old material. Measure the patch area, and cut the new sheet to fit. It's ok if the patch is a little small, and there are small gaps 1/8-inch, or so, along with the edges. A tight fit is ok, too.
Have one or two helpers hold the drywall patch in place while you fasten it to the nailing strips or joists with drywall screws. Space the screws every 7 or 8 inches along the edges and every 12 inches in the middle of the panel.
Note: Screws should be set so they are slightly embedded below the face of the drywall paper face. They should not go too deep as to break or tear the surface paper. This is very important on ceiling applications because screws set too deep will not have enough holding strength. If a screw accidentally breaks the surface, another screw can be placed within a half inch of the other.
Once the sheet is in place, finish all edges of the patch with paper drywall tape and all-purpose drywall compound:
- Embed the tape in a layer of joint compound.
- Mud over the tape with another layer of the compound. If you're worried about dust, you can use a low-dust compound.
- Apply one or two more layers of the compound, as needed, to smooth out the joints, so they are flat and blend into the surrounding surfaces.
- Cover all of the screws with two or three coats of compound, adding each coat along with the joint coats.
- Sand all of the compound with a pole-mounted sander, or sand it by hand from a ladder. To keep dust to a minimum, you can use a sander attachment hooked up to a shop vacuum, or, for small areas, using a wet-sanding sponge. Wear goggles to keep dust out of your eyes.
What If You Have Loose-Fill Insulation?
If you have loose-fill attic insulation, it might contain asbestos, but this is the exception. The most common types of loose-fill insulation are fiberglass, cellulose, and rock wool, and none of these contain asbestos. Watch out for vermiculite insulation, which has a pellet shape and sometimes a mica-like sheen, because it may contain asbestos. If your attic has vermiculite insulation, have a sample tested at a lab; if it tests positive for asbestos, contact the local health or building department for recommendations.
Loose-fill insulation is easy to move, but it is a little messy. You can pile it up to the sides of the patch area, or scoop it up with a dustpan and place it in a garbage bag for temporary storage. Do not compress the insulation because this diminishes its insulating quality. Keep it fluffy.