How to fix drywall cracks so they don't come back

Why does drywall crack, and why does the same crack come back?

Gypsum board doesn't move. The wood behind it does. Building Science Corporation's report on drywall and truss uplift lays it out: lumber shrinks as it dries, much more across the grain than along it, so studs get thinner but not shorter, and deep floor framing and built-up headers shrink the most. The board is screwed to all of it. Something has to give, and it gives at the weakest line, which is a seam or the corner of an opening.

Four patterns cover most of what you will see:

• A straight crack down a seam. The joint tape let go or was never bedded in enough compound.
• A diagonal crack from the corner of a door or window. The header above the opening shrank or moved; BSC notes that engineered headers don't shrink and sawn ones do.
• Nail pops. BSC's explanation is that nails don't push out; the wood shrinks away from the back of the board and leaves the nail head standing.
• A crack where the ceiling meets an interior wall that opens in winter and closes in summer. That is truss uplift, and BSC says flatly that it can't be prevented, only accommodated.

A patch that is stiffer than the movement, or thinner than it, cracks again on the same line. Caulk and a swipe of spackle are both in that category. The repair below opens the crack, embeds tape, and builds three coats wide enough to hide it.

Mesh or paper tape for drywall cracks, and which compound?

Paper tape works with any joint compound; mesh tape needs setting-type compound for the first coat. These two choices go together. USG's submittal for its fiberglass tape says setting-type compound, not ready-mixed or powder drying-type, is recommended for the first coat over the mesh. Paper tape can be bedded in either. So if the only compound you own is a tub of premixed all-purpose, the tape is paper.

Setting-type compound is why a crack repair can take two coats in one afternoon. It hardens on the bag's clock no matter the humidity, shrinks little, and is the right fill for anything deeper than a skim. USG also says not to use it for thin skim coats, and a batch that dries before it sets may not bond. Premixed compound is the better last coat: it spreads thinner and sands easier. The combination used below is setting-type for tape and fill, premixed for the finish.

Materials to fix drywall cracks on one wall, with quantities

The case: a 6 ft crack along a vertical seam, a 2 ft diagonal crack above a door corner, and four nail pops. That is 8 ft of crack to treat as a finished joint. The site's drywall calculator figures compound at 0.55 kg per meter of joint at a Level 4 finish; 8 ft is 2.44 m, so about 1.34 kg, or 3.0 lb, before the nail pops.

Per pound, the 18 lb bag costs $0.80 against $2.99 for the 3 lb bag, so the big bag is cheaper even if half of it goes back on the shelf. Mesh instead of paper would be $12.99 for 300 ft of FibaTape at Menards, which is fine here because the first coat is setting-type. Paint to match is not on the list. For a whole room of new board, the drywall calculator figures sheets, tape and compound from dimensions, and the paint calculator the gallons for the wall afterward.

Tools for drywall crack repair

You need a utility knife, a 6 in. taping knife, a 10 or 12 in. knife for the finish coat, a mud pan, a drill-driver, a sanding block or pole that takes screens, a bucket and a stir stick, drop cloths and a NIOSH-approved respirator. USG's sheet calls for the respirator and for a sander with a vacuum attachment, or wet sanding, to keep dust down. If you own a shop vacuum, a vacuum sanding head is the one upgrade I'd buy. A HEPA-filtered unit is what USG names.

How to fix drywall cracks, step by step

1. 1. Decide whether it is a patch job at all

   Walk the house before you open a bag. Check whether doors latch without lifting, whether trim has gaps that weren't there, and whether other openings have the same diagonal cracks. Penn Valley Engineering groups those with drywall cracks as signs of foundation movement.

   Check: one or two isolated cracks and nothing else on that list. Otherwise stop here and call a structural engineer before a drywall contractor.

2. 2. Open the crack and cut away loose tape

   Run the utility knife along the crack to cut a shallow V, and peel away any tape that has lifted until you reach tape that is stuck tight. Scrape off loose compound and wipe the dust. In a pre-1978 house, the paint you are cutting and scraping may contain lead: mist it first and vacuum instead of sweeping.

   Check: every edge you will tape over is solid; press along it and nothing flexes or crackles.

3. 3. Fix the nail pops with screws

   Drive a new drywall screw into the stud next to each popped nail so the board is pulled tight to the framing, then set the nail head below the surface. BSC's advice for new work is shorter screws and adhesive, because the wood keeps shrinking away from long fasteners.

   Check: press the board beside each fastener and it doesn't move; no screw head breaks the face paper.

4. 4. Bed the tape in setting compound

   Mix only as much Easy Sand 45 as you can use in its working time; the bag sets in 50 to 65 minutes and USG says not to re-temper it. Fill the V, lay a thin coat over the crack, press the paper tape in and knife it down, leaving about 1/32 in. of compound under the feathered edges and a thin layer on top. Keep the room at 55°F or warmer.

   Check: no bubbles or dry spots under the tape when you look at it in raking light; the edges are bedded, not floating.

5. 5. Fill coat, wider

   After the tape coat has set, apply the second coat, feathering about 2 in. past the first on each side. With a 6 in. first coat that makes the second about 10 in. wide. Fill the nail pops at the same time.

   Check: the tape is covered but its outline may still show; there are no ridges you can catch with a fingernail.

6. 6. Finish coat with premixed compound

   With the 10 or 12 in. knife, lay the third coat 2 in. past the second on each side, about 14 in. wide. USG's guide is specific that the finished joint should be a gradual arc, not flush and flat with the board, which is what hides it.

   Check: a straightedge laid across the joint rocks gently on a low crown, with no hollow at either edge.

7. 7. Sand with 150-grit or finer, and control the dust

   Once the finish coat is fully dry, sand lightly with the 220-grit screen or 150-grit paper, or wipe with a damp sponge, which USG calls the preferred alternative when little sanding is needed. Don't sand down into the board's face paper; USG warns the raised fibers show after painting.

   Check: in raking light from a flashlight held flat to the wall, no scratches, no fuzz and no visible edge.

8. 8. Prime, then paint

   USG wants joint compound dry, dust-free and primed before paint, with a high-solids flat primer such as First Coat. The compound and the board's paper soak up paint differently, and primer evens that out.

   Check: after the first coat of paint, look along the wall at a low angle. No dull or shiny stripe where the repair is.

What is the best sandpaper grit for drywall?

USG gives the numbers: 150-grit sandpaper or finer, 220-grit abrasive mesh or finer, or 80-micron sanding film or finer. USG warns that coarser grits leave scratches in the compound that show after painting, so the 80 and 100-grit screens sold on the same rack are coarser than anything USG recommends for a finish. For a crack repair done in thin coats, a 220 screen and a damp sponge are all the abrasive you need.

Ceiling cracks that open every winter: truss uplift

If the crack is at the ceiling-wall corner, opens in winter and closes in summer, taping it harder won't help. The trusses lift as their top chords, out in the cold attic, and bottom chords, buried in insulation, dry at different rates. BSC's fix is to let the ceiling float: no ceiling fasteners or adhesive within 18 in. of interior partition top plates, so the board bends instead of cracking. On an existing ceiling that means backing out the screws along that line, supporting the board edge with drywall clips as BSC's drawings show, and taping the corner once. That is carpentry more than finishing, and it is the repair that lasts.

Mistakes that cost money to fix

Should you fix drywall cracks yourself or hire a taper?

For a repair this size, do it yourself: $68.23 of material against about $336.49 hired. The BLS May 2025 mean wage for tapers, the trade that finishes drywall joints, is $34.96 an hour. Drywall installers average $30.58. BLS employer-cost data for construction put total compensation at 1.4381 times wages in June 2026, so a taper costs an employer $50.28 an hour, and with a 30% markup for overhead and profit (my assumption) the hour bills at $65.36.

Doing it yourself saves $268.26, or $67.07 for each of the four hours, nearly twice what the taper earns. On a small repair the hired number is also the least reliable one on this page, because three short visits to one wall is exactly the kind of job contractors price with a trip charge or a minimum, and I found no public figure for either. The honest trade is this: you save the money and give up the finish of someone who does it every day. On a wall with a flat paint, a careful first-timer gets close. On a ceiling under a raking window light, or on a wall you plan to paint in eggshell or darker, paying a taper is the cheaper outcome.