How to Permanently Fix a Drywall Crack
Carve out cracked drywall joints, stabilize loose drywall, embed reinforcing tape with setting-type compound, and feather wide coats for an invisible, permanent repair.
- Read the tools, materials, safety notes, and steps below for free.
- Tap Start Camera Coach when you want hands-free voice help.
- Allow camera and microphone. Point your phone at the work; the coach watches your progress and tells you the next step.
🧰 Required Tools & Equipment
- ✓ Utility knife
- ✓ 6-inch taping knife
- ✓ 10-inch or 12-inch taping knife
- ✓ Mud pan
- ✓ 220-grit sanding sponge
- ✓ Cordless drill with Phillips bit
📦 Materials & Supplies
- ✓ Setting-type joint compound (hot mud)
- ✓ Fiberglass mesh tape or paper drywall tape
- ✓ 1-1/4 inch drywall screws
- ✓ PVA drywall primer
⚠️ Safety Checkpoints & Warnings
- • Wear an N95 dust mask and safety goggles when carving gypsum, mixing powder, and sanding overhead.
- • Use a stable stepladder on level ground for ceiling work; never overreach beyond your arm's natural extension.
- • Check behind the drywall for hidden electrical wiring or plumbing before driving new support screws.
📋 Step-by-Step Guide (6 Steps)
Carve a V-Groove Along the Crack
Hold your utility knife at a 45-degree angle and score both sides of the crack to create a distinct V-notch. Remove all loose gypsum core and torn paper face along the entire damaged line. Brush away chalky dust thoroughly so new compound can bond directly to solid core.
- • A continuous, clean 1/8 to 1/4-inch deep V-shaped trench along the entire crack path.
- • Zero loose paper shreds, crumbling gypsum flakes, or paint lips bordering the channel.
- • Mudding directly over a hairline crack without widening it first.
- • Leaving loose, torn surface paper that will bubble under wet compound.
Fasten Loose Drywall to Framing
Press firmly on both sides of the crack to check for structural deflection or bounce. If the drywall moves, drive 1-1/4 inch drywall screws into the nearest framing studs or joists on both sides of the crack. Sink screw heads just below the paper surface without tearing through the paper face.
- • Screws countersunk slightly below flush with intact paper dimples.
- • Drywall remains perfectly rigid with zero movement when pressed firmly with a thumb.
- • Over-driving screws so deeply that they punch completely through the paper, offering zero hold.
- • Skipping screw reinforcement on a ceiling joint that flexes under pressure.
Fill the Groove with Setting-Type Compound
Mix setting-type joint compound (hot mud) to a peanut-butter consistency. Load the 6-inch knife and press the compound firmly into the V-groove at a 45-degree angle, forcing mud all the way to the bottom. Scrape the surface nearly flush with the drywall plane.
- • The V-groove is completely packed solid with no air voids or recessed gaps.
- • Excess mud is scraped flush with the surrounding wall surface.
- • Using regular pre-mixed bucket mud, which shrinks and cracks in deep grooves.
- • Leaving a thick, rounded hump of compound that requires excessive sanding later.
Embed Reinforcement Tape
Center fiberglass mesh tape or paper drywall tape directly over the filled crack while the base mud is still pliable or set. If using paper tape, bed it into a thin layer of wet compound and wipe down firmly with the 6-inch knife from center toward edges to squeeze out trapped air. If using mesh, apply flat and coat tightly.
- • Tape is centered directly over the crack line with no wrinkles or ripples.
- • Tape lies perfectly flat against the surface with mud completely filling mesh squares or under paper.
- • Trapping air bubbles underneath paper tape by not applying enough bedding mud.
- • Allowing mesh tape to bubble or overlap itself.
Apply Wide Feathering Coats
Switch to a 10-inch or 12-inch taping knife to apply a wider coat of compound over the taped area. Feather the outer edges down to zero by applying firm pressure on the outer blade edge and lighter pressure near the center. Extend the repair 6 to 8 inches out on each side to disguise the ridge.
- • A wide, flat band of compound spanning 12 to 16 inches total width across the repair.
- • Outer mud borders taper seamlessly into existing drywall with no distinct ledge.
- • Keeping the repair too narrow, creating an obvious convex speed bump on the wall.
- • Applying uneven pressure, gouging blade tracks across wet compound.
Sand Smooth and Inspect with Raking Light
Once completely cured, gently sand the feathered perimeter and high spots using a 220-grit sanding block in light circular motions. Hold a bright work light or flashlight parallel (raking) across the surface to identify any shadows, ridges, or pinholes. Wipe dust off with a dry microfiber cloth before priming.
- • Uniform, velvety smooth surface with no visible transition between mud and existing wall under raking light.
- • Tape pattern remains completely hidden under the sanded mud layer.
- • Over-sanding the center until the mesh or paper tape is exposed and scuffed.
- • Sanding without raking light, missing severe humps that only appear after painting.
Credit: inspired by an original tutorial by Komar Project — watch the original on YouTube.
Don’t have everything?
- No 10-inch or 12-inch taping knife? 6-inch taping knife applied in overlapping staggered passes
- No Setting-type joint compound (hot mud)? All-purpose pre-mixed joint compound (allow 24h drying per coat and expect slight shrinkage)
- No Mud pan? Stiff flat plastic tray or wide putty pan