Metal roof screws leak because the small rubber washer under each head stops sealing the hole. It cracks, gets crushed by a screw driven too hard, or loses its grip when the screw works loose as the panel moves with the heat. Every screw is a tiny hole, and the washer is the only thing keeping it shut.
The short version
- Screws only leak on exposed fastener panels, the kind with visible screw heads on the surface.
- The usual causes are a worn washer, a screw driven too tight or too loose, and a screw that has backed out.
- Sometimes the screws are fine and the leak is at a pipe boot, a vent or a flashing nearby.
- A leak that is caught early is often a small repair, not a new roof.
Which metal roofs have screws that can leak?
Only exposed fastener panels have screws that can leak, because the screws go straight through the face of the metal. The Building America Solution Center describes them as attached using gasketed screws (opens in a new tab), meaning each screw wears a rubber washer.
Standing seam panels hide their fasteners under the seams, so there is no screw head sitting out in the rain. If you are weighing the two, our metal roofing installation page explains who each one suits.
What happens to the washer under the screw?
The washer wears out, and once it stops pressing evenly on the panel, water finds the hole. The washer has one job, which is to fill the gap between the screw head and the metal. Rubber is a soft material sitting in the weather on a hot roof all year, so it does not last as long as the metal around it.
This is also why people say a new metal roof is “maintenance free” and then get a surprise. The panels may be fine for decades. The washers are the part that gets old first.
Can a screw be too tight or too loose?
Yes, both, and both leak. The Building America Solution Center says don’t underdrive or overdrive (opens in a new tab) the fasteners, and that the rubber washer should seal the metal surface but should not be pressed. Too loose and the washer never seals. Too tight and it gets squashed or split.
The Insurance Institute for Business & Home Safety gives the same warning for metal panel roofs: avoid over or under tightening (opens in a new tab) so the seal works without damaging the rubber washers. A screw that was driven wrong on day one can leak the first winter, and a roof that looks perfect from the yard can still have a few of them.
Why do screws back out over time?
Metal grows and shrinks with the temperature, and a screw holding the panel in place gets pulled on every time it does. After enough hot days and cold nights, a screw can work loose and lift a little, leaving a gap under its washer.
The same movement is why the ridge needs care. IBHS says ridge flashing requires expansion joints (opens in a new tab) to prevent leaking around the screws. A raised screw head is easy to spot up close and nearly impossible to see from the ground.
What are the signs a screw is leaking?
Most of the time the first sign is a drip or stain inside, not anything you can see on the roof. This table links what you notice to what we would look at first.
| What you notice | A likely cause | What gets checked |
|---|---|---|
| Drip or stain after any rain | A worn washer or a loose screw | The screws along the line of the stain |
| Leaks only in wind-driven rain | A raised screw or a bad seam lap | Screws near the edges and overlaps |
| Stain near a pipe or vent | The boot or flashing, not the screws | The rubber collar and the seal around it |
| Stain near the ridge | Ridge screws or a missing expansion joint | The ridge cap and its fasteners |
Keep in mind that where the stain shows up inside is rarely right under the leak. Water runs along the underside of the panel and the framing before it drops.
Is it really the screws?
Often it is not. Pipe boots, vents and flashings leak on metal roofs just as they do on shingle roofs, and they get blamed on the screws all the time. A pipe boot is the rubber collar around a pipe where it comes through the roof, and the cheap ones crack in 3 to 5 years.
We say caulk is a scheduled leak. Anything that depends on sealant to keep water out has a life of about 5 to 10 years, so a roof patched with a tube of sealant every other summer is a roof telling you something. Flashing repair deals with those joints properly, instead of smearing more sealant over them.
If you have been sealing the same spot over and over, stop and get the cause found. Sealant on top of a failed washer hides the problem for a season.
What does it cost to fix leaking metal roof screws?
A small sealant reseal typically runs $400 to $850, and finding the exact entry point with a hose test or attic tracing typically costs $150 to $400. Those are typical ranges for work around Ellicott City, not a quote, and the price depends on how many screws have failed and how steep and tall the roof is.
If a few screws have failed, a roof repair is usually the answer. If the washers across a whole roof are tired, replacing screws one at a time stops making sense, and that is a conversation about the roof as a whole. We would rather tell you that plainly than keep selling you repairs. Our free roof inspection includes a walk on the roof, so it is the quickest way to learn which of the two you have. It is a snapshot, not a guarantee, so a hard storm afterward can change things.
Common questions
Can I just tighten the screws myself?
Please don’t start with that. A screw that is already tight can be driven too far and split the washer, which makes the leak worse. Walking a metal roof is also slippery and easy to dent. Leave it to a roofer who can tell a loose screw from a failed washer.
Will roofing sealant over the screw fix it?
It can slow the drip for a while, but it is a patch. The washer underneath is still worn, and sealant has a short life on a hot roof. If the leak keeps coming back, the sealant is covering the cause.
Do metal roofs with hidden fasteners leak at the screws?
Not at the surface, because there are no screw heads out in the weather. They can still leak at flashings, vents and seams. Our article on how safe metal roofs are covers what a well detailed one looks like.
What to do next
If you have a drip under a metal roof, or a stain you cannot explain, call us and we will look at the screws, the washers and everything around them. The free inspection is the place to start, whether the roof is five years old or fifteen.
