What Causes Drywall Cracks? Diagnose Before You Repair

If you want to fix drywall cracks for good, you have to find and stop the cause. If not, taping and finishing is pointless. The repair may look good for a few weeks or months, but the crack will most likely return.

Drywall consists of a gypsum core wrapped in paper. Gypsum on its own is brittle and cracks easily but the paper cover stabilizes the core and provides a smooth finish surface. Under normal conditions, cracks normally don't appear in the middle of sheets. Because drywall joints are the weakest part of the wall, most cracks show up where two sheets meet. When the two sheets on either side move in opposite directions, the seam cracks. Cracks along seams may indicate poor taping methods or the wrong material was used. You can read up on those types of cracks in Why Does Drywall Mud Crack? 7 Taping Mistakes That Cause Cracked Seams. Cracks can also run through a sheet, usually starting at the corner of a door or window, where stress builds up. Where the crack sits and which way it runs tells you a lot about what moved.

Read the crack: pattern, likely cause, how concerned

1. Poorly placed or failed drywall fasteners

Drywall can be secured with nails, screws or adhesive. Any of these can hold drywall and prevent cracking. When driving screws or nails, don't let the head of the fastener break through the paper. A head driven through the paper loses its holding power and lets the sheet float. Corners and edges need more fasteners than the field, and nails alone need closer spacing than screws. If any of this is ignored, the sheet isn't really held. When the building moves, even slightly, poorly fastened drywall can shift away from the sheet next to it, causing cracks to form or nails to pop.

How to check: push on the drywall on both sides of the crack. If you feel even a little movement, the sheet needs to be secured before you repair the crack. Screw pops nearby are another sign the fasteners failed. Add screws around the crack until all movement stops. When you are ready to fix them, review Drywall Screw Pops: Why they Happen and How to Fix Them.

How far apart? Fastener spacing depends on the fastener, the framing spacing, whether it's on walls or ceilings, and whether adhesive is used. The rules are in GA-216 and IRC Table R702.3.5. Use our fastener spacing calculator instead of guessing. See also options for securing drywall and number of screws per sheet.

Not sure your fasteners are close enough? The Fastener Spacing calculator gives maximum spacing from the IRC Chapter 7 tables for your framing, fastener and adhesive.

2. Not enough drywall backing

Before hanging drywall, check that there is enough backing securely installed in the right locations. Inside corners of a room are often overlooked. If drywall is hung without enough backing, the sheets move and cracks form.

Pushing on the sheet around the crack tells you a lot. If it rests solidly against a stud, the backing is there and only the fasteners failed. If there's no stud behind the spot that moves, there probably wasn't enough backing installed during framing.

Fixing missing backing isn't easy. You have to get behind the drywall and attach wood or metal backing to the structure. Then you can secure the drywall to it and repair the crack. Sometimes you can reach the back from an attic or crawl space, but usually you can't.

If you can't get behind it, cut a hole in the drywall and install backing where it's missing. It may seem like a lot of work, but if the drywall isn't secured before taping, it will crack again. Sometimes you can get away with a small square opening at the crack and a strip-backed patch: attach small wood strips behind the opening so they tie both sheets together. Your goal is to stop the two sheets from moving in opposite directions. If that isn't an option, you'll need to cut a large opening so additional backing can be fastened to the framing. You may want to cut the drywall back to the nearest stud, add small pieces of 2x4 lumber to the existing structure, then secure both the patch and the existing drywall to it. See how to cut drywall and How to Repair Holes in Drywall.

3. Seams over headers and openings

The areas above doors and windows are common places where cracks appear. The weight above an opening is carried by the header and down the jack studs on each side, so those spots carry more stress than the rest of the wall. Wood headers also shrink as they dry. When you are first installing drywall, avoid placing seams on or near jack studs. Joints placed anywhere within about 12 inches of the edge of a door or window are very likely to crack at some point in the future (see GA-216 4.6.4). If you need a seam above or below an opening, put it near the middle of the opening. If possible, hang a sheet so it overhangs the opening by at least 12-16 inches on either side.

The same rule applies above any load-bearing area. Cracks over wide openings in open-concept rooms usually mean the seam was put in a bad spot. In those cases even when the sheet feels solid cracks can appear if the structure under it moves. More screws can strengthen the joint, but if the movement is significant, no amount of fasteners will stop the crack. The fix may be a better seam location (cut out and re-hang that piece) or a control joint.

4. Corner cracks

Inside corners crack for three main reasons: missing backing (section 2), tape failure (see why drywall seams crack), or two framing members that move independently, like what can happen where walls and ceilings meet (section 6). To diagnose the cause, push on both sides of the corner to identify if it is a fastener or backing issue. If so, re-secure and re-tape the corner. If the crack comes back seasonally, especially at the ceiling line, treat it as movement and use a flexible detail instead of more tape.

5. Framing lumber shrinkage

New framing lumber continues to dry and shrink after the house is closed in and heated. Floor joists, plates, and headers shrink the most. Most lumber shrinkage happens within the first year, which is why cracks and nail pops show up in new construction, and why it's worth waiting until after the first heating season to repair them. Once framing lumber reaches its EMC (equilibrium moisture content), these types of cracks shouldn't reappear.

Equilibrium moisture content (EMC)

Framing lumber is usually kiln-dried to a maximum of 19% moisture content when it leaves the mill. After a house is closed in and the heat and air are running, the wood slowly dries toward its equilibrium moisture content (EMC): the moisture level where it stops gaining or losing water to the air around it. In a conditioned building, EMC typically settles somewhere between 7% and 15%. EMC depends on temperature and humidity, so it shifts with the seasons and varies by region. As the framing dries, it shrinks across the grain. Wall plates, floor joists and headers all lose a little height. Drywall fastened over that framing has to absorb the movement, and that's why new homes often show cracks and screw pops in the first year or two.

How fast and how much the framing shrinks depends on several things, according to WoodWorks:

• how well the lumber was protected from rain and moisture during construction
• the wood species
• the time of year it was built
• the regional climate
• how soon after framing the HVAC system was installed and turned on
• how soon after framing the interior finishes, including drywall, went up

Ideally most shrinkage happens before the drywall is hung. When a house is framed with wet lumber and finished quickly, more of that movement shows up in drywall cracks. Builders can mitigate some of the wood shrinkage problems, for example by keeping the framing dry and drying in the house quickly. Plumbers can drill oversized or vertically slotted holes where pipes pass through studs, so a pipe doesn't bind as the wood around it shrinks.

6. Truss uplift (winter gap at the ceiling)

In houses framed with roof trusses, the bottom chord sits in cold, damp attic insulation in winter while the top chords are warmer and drier. This difference in moisture level can cause trusses to bow upward and lift the ceiling off the top of interior walls. The result is a crack or gap where the ceiling meets an interior wall. This type of gap opens in winter and closes in summer months. This isn't considered a structural failure, but taping it won't hold. Options:

• Drywall clips / floating corner: clips on the top plate hold the ceiling edge without tying it to the trusses.
• Flexible inside corner bead that can flex with small movement. Strait-Flex
• Crown molding fastened to the ceiling only, so it moves up and down with the ceiling and slides over the wall.

7. Settling and foundation movement

All buildings settle some. Houses built on fill or expansive clay, or with drainage problems, can move more. Warning signs that it isn't just drywall: stair-step or diagonal cracks in several rooms, cracks that keep growing, doors and windows that stick or won't latch, sloping floors, or matching cracks in the foundation or exterior brick. Don't patch these until the cause has been looked at.

8. Humidity and seasonal movement

Most seasonal movement in a house comes from wood taking on and giving up moisture as indoor humidity changes, plus truss uplift in winter. It isn't the freeze-thaw cycle. Cracks that open in the dry heating season and close in summer are moisture movement. Keeping indoor humidity stable can help, and repairs hold best when done in a "middle" season.

9. Earthquakes

Drywall is often the first part of a wood-frame house to show earthquake damage. Gypsum board damage starts as hairline cracks at joints and openings. If the damage is more extensive, cracks move to crushing at opening corners, boards separate from the studs. After a quake, document the damage before repairing. Use the levels below to judge what kind of repair it needs.

Damage levels and what the repair looks like

Adapted from Caruthers (2026), Table 4.1, which adapts Liu & Carradine. Simplified for homeowners.

Damage levels adapted from Liu & Carradine, as summarized in Caruthers (2026), Table 4.1, p. 51.

Expansion (control) joints

Where real movement is expected (long walls and ceilings, changes in framing material, or where wings of a building meet), a control joint lets the drywall move without cracking. It's a break in the board with a flexible bead, and it should line up with a matching break in the framing behind it. GA-216 directs that control joint location should be specified by an architect. Control joints are common in commercial buildings and less common in houses, but they're the right fix for a long ceiling that keeps cracking in the same spot. GA-216-2021: Application and Finishing of Gypsum Panel Products and ASTM C840, Standard Specification for Application and Finishing of Gypsum Board contain technical guidelines for control joint placement and installation.

When to call a structural engineer

Call a structural engineer (or start with a home inspector) if you see:

• cracks that keep getting longer or wider over weeks or months
• stair-step or diagonal cracks in several rooms, or matching cracks in the foundation or exterior
• doors and windows that start sticking, or floors that slope or bounce
• ceiling sag, or boards coming loose from the framing
• level 2-severe or level 3 damage after an earthquake

Photograph, date and watch

Before you repair anything, photograph each crack with a tape measure or ruler beside it, mark the ends with a pencil and write the date. Check again in a few weeks and across a season. A crack that stays put is usually safe to repair. One that grows needs a diagnosis first.

Next step: fix it

Once the drywall can't move, it's time to tape and finish. Follow How to Fix Drywall Cracks for the full step-by-step. Fixing a crack without stopping the cause is like putting a Band-Aid on a broken bone.