Most leaks on screw-down metal roofs come from the screws. The rubber washer under each screw head dries out and cracks in the sun, or the screw backs out as the panels expand and shrink with heat. Screws driven too tight, too loose, crooked or into the wrong spot also leak. The fix is to replace worn screws with new, slightly larger screws with fresh washers.
Why screws leak
- Washer breakdown: The rubber washer dries, shrinks and cracks. Many start to fail somewhere between 10 and 20 years.
- Thermal movement: Metal expands in the afternoon sun and shrinks at night. Over years, that works screws loose.
- Bad install: Over-driven screws crush the washer. Under-driven ones do not seal. Crooked ones leave a gap.
- Missed purlins: Screws that missed the wood or metal framing below never held tight.
- Rust: Old screws rust around the head and the hole.
Signs your screws are the problem
- Drips in a line that follows a row of screws
- Rust streaks running down from screw heads
- Screws that spin or stick up above the panel
- Cracked or missing washers
- Leaks that started after a hot summer
Other metal roof leak spots
Laps where panels overlap, the ridge cap, and flashing where the roof meets a wall or chimney also leak. On older roofs, rust holes in the panels themselves can let water in. Sealant at the laps dries out on the same schedule as the washers.
How screw replacement works
Check every row
Worn screws are marked across the whole roof, not just over the leak.
Remove old screws
Each worn screw comes out.
Upsize
A new screw one size larger with a new washer goes in the same hole, so it bites fresh wood or metal.
Drive it right
Snug so the washer just starts to bulge, not crushed.
Seal laps and trim
Laps, ridge and flashing are resealed where needed.
Metal roofs around Pine Bluff
We see screw-down metal roofs on homes, shops, barns and carports all around Pine Bluff, especially in the rural areas like Sulphur Springs, Hooker and Ladd, Sorrells and Baldwin, and Wilkins. Many are 15 to 30 years old and still have their original screws. The panels often have decades of life left. The screws do not.
Do metal roofs leak more than shingles?
Not when they are kept up. A well-installed metal roof with sound screws and flashing sheds water very well, and it handles wind and hail better than most shingles. The difference is maintenance: screw-down roofs have hundreds of exposed fasteners, and each one is a small seal that ages. A check every few years catches loose screws before they leak.
Is it condensation instead?
Uninsulated metal roofs on shops and barns often drip from condensation on cool mornings, which looks like a leak. If drips show up with no rain, across a wide area, it is likely condensation. See roof leak or condensation.
Can I just caulk the screws?
A dab of sealant over a leaking screw can slow it for a while. It does not fix a loose screw or a crushed washer, and it wears out fast in the sun. See is caulk a permanent roof fix.
Should I coat my metal roof?
A coating can make sense on an older metal roof with surface rust after the screws and seams are fixed. It does not replace screw work. See roof sealing and coating.
How long do metal roof screws last?
The rubber washers often start failing somewhere between 10 and 20 years.
Should all the screws be replaced?
If many are worn, replacing all of them in one visit is usually cheaper than chasing leaks.
Can you over-tighten metal roof screws?
Yes. Over-tightening crushes the washer and can cause leaks.
Do you fix metal roofs on barns and shops?
Yes. We repair metal roofs on homes, shops, barns and carports.