How to spot it
Screw heads standing proud of the panel, washers cracked or missing, rust halos around fasteners. From inside, drips that line up along purlins.
Fastener Backout, at a glance
Fastener backout is when the screws holding an exposed-fastener metal roof work loose over years of heating and cooling. The rubber washer stops sealing, water follows the screw shank, and you get drips lined up along the purlins. Small areas get re-screwed with oversize fasteners and new washers. Roofs with widespread backout usually need a full re-screw, a coating system or a retrofit. Free inspections. Call (314) 429-6000.
We see this every spring on pre-engineered warehouses, shops, ag buildings and church gyms around the metro. A metal panel in July sun gets hot enough to burn your hand, then drops toward freezing on a February night. That steel grows and shrinks every single day. The screws feel all of it.
Each cycle wallows the hole a little more. Add a washer that's dried out and cracked from twenty years of UV, and the seal is gone long before the screw actually falls out. By the time you see a screw head standing up off the panel, it's usually been leaking for a while.
What We Check
Reading A Metal Roof Screw By Screw
Purlin screws vs. stitch screws
Purlin screws hold the panel to structure. Stitch screws close the side laps. Both back out, and loose stitch screws at laps usually leak first.
Commercial metal roofingOversize replacement
We pull the old screw and drive the next size up with a fresh sealing washer, so the threads bite new steel. Over-driving crushes the washer, so we set them snug and stop.
Commercial roof repairHail and wind
Spring hail dents panels around fasteners and wind loads work them loose. Document it before anyone re-screws so the claim evidence isn't lost.
Storm damage and insuranceCoatings over fasteners
A silicone or acrylic system with fastener caps can seal a sound roof for years. It won't fix a screw that isn't biting anything.
Commercial roof coatingsWhen to retrofit
Widespread backout, rust through at laps and failed sealant usually mean a retrofit: new standing seam, or single-ply over the old panels.
Metal roof retrofit options
On The Roof
What A Re-Screw Job Actually Involves
First we figure out how widespread it is. A walk with a paint marker and a count by bay tells us whether we're replacing a few hundred screws along the eave or a few thousand across the building. We photograph a sample of washers too. A roof where every washer has cracked is a different job from one where a handful of screws stripped out.
Then the purlins. Light-gauge Z and C purlins strip easily, especially where the original installer over-drove. When an oversize screw won't grab, we add a fastener an inch or two off the old hole and seal the abandoned one. On older buildings we check for rust at purlin laps while we're up there.
End laps and ridge caps get the same attention. Panel ends lap with butyl tape and a row of screws, and when that tape dries out, wind-driven rain wicks uphill right through it. Re-sealing laps is slow, fussy work. It's where most of the labor on these jobs goes.
Last, we talk about what comes next. If the panels are sound and the rust is surface only, a full re-screw plus a coating can carry a building a long time. If the panels are rusted through at the laps, re-screwing is throwing money at it, and we'll tell you so.
Common Questions
Can I just tighten the screws that look loose?
Usually not. The hole is already wallowed out and the washer is spent. Cranking down on an old washer crushes it and it still leaks. Replace it with an oversize screw and a new washer.
How often should exposed fasteners be checked?
Walk the roof every year and after any big hail or wind event. Washer wear often starts showing in the second decade, depending on sun exposure and how carefully the screws were set.
Do standing seam roofs have this problem?
Much less. Standing seam uses concealed clips that let panels move, so classic backout is rare. Clips can still fail on a poor install, and anything that penetrates the panel still needs care.
Will a coating stop leaks from backout?
Only if the screws are tight first. We replace or reseat fasteners, cap them, then coat. Coating over loose screws just traps water.
What warranty comes with the work?
New roof systems we install carry our lifetime workmanship warranty plus the manufacturer's coverage. For repair work, we spell out exactly what's covered on the written proposal. Inspections are free.
Free Metal Roof Evaluation
Tell us about the building and where it drips, and a dispatcher will call to schedule.