Short answer
Yes. Most horizontal drywall cracks are along a taped seam and can be repaired without replacing the sheet. Refasten the drywall if it’s loose, then embed new tape over the crack using a setting-type joint compound, build two to three thin coats, sand, prime, and paint. If the crack is due to moisture or structural movement, address that first to prevent it from returning.
What causes horizontal cracks and why the method matters
Horizontal wall cracks often trace where two drywall sheets meet (typically 48 in. from the floor). They usually stem from:
- Minor framing movement or seasonal expansion/contraction
- Loose or missing screws/nails along the seam
- Failed original tape or insufficient compound coverage
- Past moisture exposure that weakened the seam
For a durable fix, you need reinforcement (tape) and a hard, low-shrink base (setting-type compound) rather than just smearing spackle into the crack.
Tools and materials
- Utility knife (sharp blades)
- Drywall taping knives: 6 in., 10–12 in.
- Mud pan or hawk
- Stud finder and pencil
- Drill/driver with drywall screw setting bit
- Drywall screws: 1-1/4 in. coarse-thread for wood studs (fine-thread for metal)
- Paper drywall tape (preferred) or fiberglass mesh tape
- Setting-type joint compound ("hot mud") 45 or 90 minute
- Lightweight all-purpose or topping compound
- Sanding sponge (fine/extra-fine) or pole sander with 220-grit
- Vacuum and drop cloths/plastic sheeting
- Primer (PVA or stain-blocking if previous staining), matching paint
- PPE: safety glasses, dust mask or respirator, gloves
Safety check
- If you suspect moisture, find and fix the leak first. Stained, soft, or moldy drywall shouldn’t be patched until dry and sound. Replace sections if crumbly or mold is extensive.
- Homes built before 1980 may have asbestos in old joint compounds and pre-1978 paint may contain lead. Avoid aggressive sanding or demolition until tested. Use lead-safe practices when in doubt.
- Turn off HVAC in the room while sanding to limit dust spread. Wear eye and respiratory protection.
Step-by-step repair
1) Inspect and prep
- Look for a straight line at about 48 in. height—likely a seam.
- If the crack is wider than 1/4 in., the wall is bowed, or there’s ongoing movement, consider calling a pro (see below).
- Lay drop cloths and mask adjacent surfaces.
2) Refasten the drywall
- Use a stud finder to locate studs along the crack. Add screws where the seam crosses studs to pull the panels tight and minimize future movement.
Screw specs:
- Spacing: every 8–12 in. along the seam on studs
- Distance from edge: ~3/8 in.
- Length: 1-1/4" for 1/2" drywall into wood studs (fine-thread for metal studs)
- Heads: slightly dimpled below paper surface (don’t break paper)
3) Open and clean the crack
- With a sharp utility knife, cut a shallow V-groove along the crack to remove loose mud/paper and create a clean bonding channel. Feather 2–3 in. beyond if old tape is blistered—remove any loose tape.
- Vacuum dust and wipe with a damp cloth.
4) Fill and tape
- Mix setting-type compound (45-minute is a good balance for DIY) to a creamy consistency.
- For gaps >1/8 in., pre-fill the groove and let it firm up a few minutes.
- Apply a thin bed of compound (6 in. knife), lay paper tape centered over the crack, and press it in, squeezing out excess and air bubbles. The tape should sit flat without ridges. Lightly cover with a thin coat to just hide the tape.
- Paper tape gives the strongest seam. Fiberglass mesh is faster but must be used with setting compound to avoid future cracking.
5) Build coats
- After the base sets hard, apply a wider coat (8–10 in.) with lightweight all-purpose or topping compound, feathering edges.
- Once dry, add a third, even wider coat (10–12 in.) if needed for a seamless transition. Keep coats thin to reduce sanding.
6) Sand, prime, and paint
- Sand lightly with a fine sanding sponge or 220-grit, just enough to knock down edges. Avoid over-sanding into the tape.
- Wipe dust, prime the repaired area (or the whole wall for best uniformity), then repaint.
Pro tips for best results
- Use a work light at a low angle to spot ridges before it dries.
- If dust is a concern, wet-sand with a damp sponge for the final pass.
- Keep your knives clean; dried mud edges cause streaks.
- In rooms with high humidity swings, consider paper tape plus setting compound for added crack resistance.
- If the crack keeps reappearing at the same seam, widen your feathering to 12–14 in., and confirm screws are holding along every stud.
Common mistakes
- Skipping tape and only using spackle—cracks will return.
- Using only premixed compound over mesh tape—mesh needs setting-type mud for strength.
- Thick, lumpy coats that require heavy sanding and expose tape.
- Not securing the drywall first—movement will reopen the seam.
- Painting without primer—flashing will show through the finish coat.
Time and cost
- Time: 2–3 hours of hands-on work spread over 1–2 days (dry/cure times vary).
- Cost: $20–$50 for compounds, tape, and sundries if you already have basic tools. Add $15–$40 for knives or a sanding pole if you need them.
When to call a professional
- The crack is wider than 1/4 in., the wall is bulging, or there’s clear ongoing movement.
- There’s water damage, mold beyond a small area, or soft/crumbly gypsum.
- Multiple long seams have failed, or ceiling cracks suggest truss uplift or framing issues.
- Your home predates 1980 and you anticipate significant sanding/disturbance—test for asbestos/lead first or use a licensed pro.
Handled as above, a horizontal drywall crack along a seam can be repaired cleanly and stay closed for the long haul without replacing the sheet.