Drywall is cheap; labor, finishing and paint are not. That is why the repair-or-replace question is really a question about the board's condition, not the size of the damage. A sound board with a big hole is often best fixed by cutting out a section and putting in new. A small-looking stain over wet, soft board always means replacement, however minor it appears.
Decide by damage type
| Damage | Usually | Why |
|---|---|---|
| Dents, dings, small holes from anchors or nails | Repair | Spackle or joint compound, sand, prime, paint. |
| Holes up to roughly hand-size (doorknob strikes) | Repair | A patch with backing, taped and feathered wide. |
| Larger holes, or several holes close together | Replace a section | Cut back to the nearest studs and install a new piece; stronger and flatter than a big patch. |
| Nail or screw pops | Repair | Reset with a screw beside the pop, then fill. Many pops in one area can mean framing movement worth a look. |
| Hairline cracks at corners of doors and windows | Repair | Re-tape with mesh or paper. Cracks that reappear or widen point to settlement, not the drywall. |
| Water stain, board dry and firm, leak fixed | Repair | Stain-blocking primer and paint. |
| Board wet more than 24 to 48 hours, soft or crumbling | Replace | The gypsum core and paper facing lose strength and grow mold. |
| Floodwater or sewage contact | Replace | Contaminated porous material cannot be reliably cleaned. |
| Sagging ceiling | Replace | Sagging board is often water-loaded or detached, and can fall. |
| Visible mold beyond a small surface spot | Replace | Mold lives on the paper facing and inside the wall; remove the material and fix the moisture source. |
Water damage: the rule that matters most
In Alabama's humidity, wet drywall does not dry on its own the way it might in a dry climate. The EPA's guidance is to dry water-damaged building materials within 24 to 48 hours to limit mold growth. Past that window, or with any floodwater, the board comes out. A common restoration practice is to cut a straight line a foot or more above the highest wet reading, remove the wet insulation behind it, dry the cavity until the studs read dry on a moisture meter, and only then rebuild.
Fix the source first. Patching over an active leak is the most common way a hundred-dollar repair becomes a thousand-dollar one. Roof leaks, failed window flashing, a supply line behind a toilet, or condensation from an HVAC line are the usual causes.
Older homes: test before you sand
Much of Birmingham's housing stock was built before 1978. Paint in those homes may contain lead, and federal lead-safe work rules apply when painted surfaces are disturbed. Separately, some joint compounds and popcorn-style ceiling textures made before the 1980s contained asbestos. Neither is a reason to panic, and both are a reason to test before sanding, cutting or scraping. A certified inspector or an accredited lab test answers the question; we do not do the testing ourselves, but we will not start dusty work on suspect material without an answer.
Getting a patch that disappears
- Feather wide. A patch's edges should taper out several inches beyond the repair, not end in a ridge.
- Prime the patch. Joint compound absorbs paint differently from painted wall and shows as a dull "flash" if you skip primer.
- Match the texture. Orange peel, knockdown and hand textures each need their own technique. Practice on scrap first.
- Paint the whole plane. Spot-painting even with leftover paint from the same can rarely blends; paint corner to corner.
- Mind the light. A wall lit from the side by a window shows every flaw. Check under that light before painting.
Ceilings are a different job
Ceiling drywall carries its own weight overhead, so the tolerance for damaged board is lower. Any sag, any softness, or a stain that keeps spreading means the board should come down. Ceiling patches are also harder to hide because light hits them at a low angle. When a ceiling has several repairs, re-texturing and repainting the whole ceiling is often the better value.
DIY or hire it out?
Small holes, nail pops and hairline cracks are reasonable homeowner projects with a putty knife, compound, sandpaper and patience; the skill is in feathering and priming, not strength. Hire it out when the repair is on a ceiling, when texture has to match a large area, when more than a few square feet of board must be replaced, when water damage is involved and the cavity needs drying and checking, or when the house is old enough that lead or asbestos testing applies. Also hire out anything near electrical boxes or plumbing you are not sure about. For landlords, a patch that shows will be noticed by the next tenant at move-in and by a buyer at sale, so professional finishing usually pays for itself.
Estimating materials
Standard sheets are 4 by 8 or 4 by 12 feet; half-inch board is typical for walls, and ceilings often use lighter sag-resistant board or 5/8 inch. Moisture-resistant board belongs in bathrooms and laundry rooms. The drywall sheet calculator converts a wall or ceiling area into a sheet count. Add a waste allowance for cut-outs and offcuts.