Do metal roof screws need to be replaced?

Yes, eventually. Heat makes the panels grow and shrink every day, and over the years that works screws loose and wears the rubber washers. SFS says to assume screws past 20 years are on borrowed time. Check them twice a year and after hail or high wind, and look for rust stains, lifted heads and cracked washers.

What size screw replaces an old metal roof screw?

One size wider than the original. The old screw has stripped its hole, so a screw of the same size won't cut new threads and will sit loose. SFS gives the example of a #14 replaced with a #17. Match the length to the panel and what's under it, and ask for a screw with good corrosion resistance.

Should I replace a few screws or all of them?

If a handful leak on a young roof, spot-fix them. If the roof is 15 to 20 years old and screws are failing all over, a full swap is better. Fixing one leak at a time on an aging roof just moves the drip to the next screw, and every visit costs another service call.

Metal Roof Screw Replacement in Midland, TX

Metal Roof Screw Replacement: Where the Fasteners Fail

SFS projects 40 to 70 years for the metal roof itself. The screws, their washers and the threads they bite into wear out well before that. These are the five places a screw job actually happens.

Hand holding an oversized replacement roofing screw beside an old rusted screw on a ribbed panel

Oversized Replacement Screws

When an old screw comes out, its hole is worn. A new screw of the same size has nothing fresh to bite. The fix is a screw one size wider that cuts its own threads. SFS gives #14 to #17 as the example. Another contractor's guide calls these oversized screws for stripped holes.

Spot repair, a few screws: $150 to $600 (contractor guide)
Problem sections: $600 to $1,500
Whole roof: $1,500 to $4,000 or more

Close view of cracked rubber washers under metal roof screw heads with rust stains

Washer and Gasket Failure

The rubber washer under each screw head is the actual seal. Sun dries it out, and the panel moving under it as it heats and cools can push the screw off its seat or tear the washer. Once a washer cracks, water gets under the head and into the building.

Row of roofing screws showing one over-driven with a bulging washer and one loose

Over- and Under-Driven Screws

How hard a screw is driven matters as much as its age. An over-driven screw crushes the washer so it bulges out at the sides and leaks. An under-driven screw leaves a gap under the head. A screw driven at an angle doesn't seal all the way around. A good roofer will set the clutch on the driver so each washer just compresses.

Metal ridge cap on a ribbed roof with new screws along the ridge and foam closures

Ridge Cap and Trim Fasteners

Ridge caps, rake trim and eave trim have their own screws and sealant. SFS notes that sealants under trims and around roof transitions break down and have to be redone. Ask whether the quote covers trim fasteners, or only the screws in the flat of the panels.

Side lap of two metal panels joined with small stitch screws and butyl tape

Lap Sealant and Stitch Screws

Where two panels overlap, water can creep uphill into the lap by capillary action, according to SFS. The lap is held with short stitch screws, about 3/4 to 1 inch long, that join the two sheets without reaching the framing. Butyl tape or sealant under the lap does the sealing.

Resealing seams: $250 to $1,100 (HomeGuide)

Roofer in a harness and wide-brim hat kneeling on a light grey standing seam roof, checking a seam

Why Midland homeowners call Midland Metal Roofing

Free quotes, no obligation to hire
Panel, gauge and price in writing before any work
Your request goes to one Midland roofer, not a call list
Homeowners never pay us for the referral

Spot Fix or Full Screw Swap?

Fix the few leaks or replace every screw? That depends on the roof's age and how widespread the failures are.

A few leaks on a roof under about 15 years old
replace those screws and check the washers around them.
Leaks in several places on an older roof
a full swap gives every hole a fresh screw and washer. One contractor's guide lists roof age past 15 to 20 years as a sign it's time.
Rusted screws
ask for a more corrosion-resistant replacement rather than the same type. SFS suggests stainless bimetal screws where the old ones rusted.
Before work starts
SFS suggests marking the fastener pattern and checking for corroded purlins or decking that a new screw can't grip.
Don't over-fasten
extra screws beyond the panel maker's pattern add holes and stop the panels from moving with the heat.

If the leak isn't at a screw, the metal roof repair page covers flashing, boots and seams. A full coating usually includes sealing every screw head, and after a storm, start with the hail damage page. Shop owners can also see metal building roofs.