The short answer
How Heat Affects Drywall
Drywall is a rigid panel made of gypsum plaster sandwiched between paper layers. It is attached to wood or metal framing. During a heat wave, the air inside your home becomes hot and dry. This causes the wood framing to lose moisture and shrink slightly.
As the framing shrinks, it pulls on the drywall panels. The joints where panels meet are filled with joint compound, which is more brittle than the panel itself. Under stress, that compound can crack. You might notice thin, straight cracks along seams or small cracks near corners and door frames.
Humidity and Temperature Swings
Heat waves often bring big swings in humidity. Even in a dry heat, the air can hold more moisture when it is hot. When humidity rises, the wood framing expands. When it drops, the wood shrinks again. This repeated movement stresses the drywall.
In many regions, summer brings both hot, humid days and cool, dry nights. Those swings in moisture can make existing cracks worse or create new ones. The effect is usually gradual, but a sudden heat wave can trigger visible cracking.
If you notice cracks appearing after a heat wave, it is a sign that your home's materials are responding to the environment. It is not usually a structural emergency, but it is worth monitoring.
- Check for cracks along seams and around windows and doors
- Feel for drafts near cracks that might indicate air leaks
- Look for any signs of water stains, which could point to a separate issue
- Monitor crack size over a few weeks to see if they grow
- Keep indoor humidity steady with a dehumidifier or air conditioner
When to Call a Pro
Not every crack needs professional attention. Hairline cracks from seasonal movement are common and can be patched with joint compound and paint. However, if cracks are wide, jagged, or accompanied by sagging or bulging drywall, you should have a professional look.
A water damage inspection can determine if moisture is involved. If the cracks appear after a heat wave but you also notice water stains or musty odors, there may be a hidden leak. Local water damage pros can assess the situation and recommend repairs.
For simple cosmetic cracks, you can patch them yourself. For larger issues, a drywall repair specialist can replace damaged panels and re-tape the seams.
Repairing Cracks
For small hairline cracks, you can repair them with a flexible patching compound. Apply the compound with a putty knife, let it dry, then sand and paint. This is a simple DIY task that most homeowners can handle.
For larger cracks or cracks that keep returning, you may need to replace the drywall panel. This involves cutting out the damaged section, installing a new piece, and taping the seams. It is more involved and may require professional help if you are not experienced.
If the cracks are related to water damage, you need to address the moisture source first. Otherwise, the cracks will reappear after repair. A water damage inspection can identify the cause and guide the right repair.
Talk to someone now
Phones are answered 24/7 for Milwaukee and nearby communities.
Call Now (414) 348-0250Frequently asked questions
Can heat alone crack drywall?
Yes, heat alone can cause drywall to crack. High temperatures dry out the wood framing, causing it to shrink. The drywall, attached to the framing, then experiences stress at seams and corners, leading to cracks. Humidity changes during heat waves can worsen the effect.
Are heat cracks a sign of structural damage?
Usually not. Hairline cracks from heat and humidity are common and cosmetic. However, if cracks are wide, jagged, or accompanied by sagging or water stains, they may indicate a larger issue. In that case, have a professional inspect your home.
How can I tell if a crack is from heat or water?
Heat cracks tend to be thin, straight, and appear along seams or corners. Water damage cracks are often accompanied by stains, bubbling paint, or soft drywall. If you see any discoloration or feel moisture, assume water is involved and address it promptly.