Roof Systems
Metal Roof Retrofit in Federal Way, WA
Walking an exposed-fastener metal roof with a screw gun and a bag of oversize fasteners, looking for the ones that have backed out, is where a retrofit starts. Exposed-fastener panels are held down by screws driven through the face of the metal, each with a rubber washer. Over the years the washers harden and crack, the screws loosen as the panels move, and each fastener becomes a small hole. A Federal Way, WA building with a roof like that may leak at hundreds of points while the panels themselves are still sound.
The question that changes the plan is how much of the roof is salvageable. The walk covers fasteners, laps, ridge and rake trim, rust at edges and the condition of the framing below, and it ends with a decision between repair, restoration and overlay.
What fixes a roof of failing screws?
The direct fix is to replace the fasteners. The crew removes each failed screw and drives a larger one with a new washer into sound framing. If the old hole is stripped, an oversize screw bites fresh metal. In some roofs, the purlins have rusted or the screws have pulled out of wood, and a bigger screw will not help. We test with a pull test at several points and write the replacement pattern around the weakest results.
Replacement is labor-heavy but cheap in materials, and it restores most of the roof's life if the panels are sound. A crew with the right sequence works from the ridge down in strips, replacing every fastener in a strip before moving on, so the roof is never left half-fixed and half-open when the day ends. We pair it with sealing the laps, since overlaps between panels are the other common leak path. Butyl tape goes between laps where the panels are lifted and re-set, and a bead of sealant closes the ends. The work moves in sections, each one finished and checked the same day. A commercial roof repair of this kind is the lowest-cost route when the metal is good.
What about laps, ridge and trim?
Trim does a lot of waterproofing on a metal roof. Ridge caps, eave trim, rake trim and gable flashings hold the edges against water and wind. Their fasteners fail the same way as the panels' do, and the sealant under them dries out. We check each trim run, replace failed fasteners and renew sealant, and where the trim is bent or corroded we replace it.
The laps between panels need attention along the whole run. We look for gaps where panels have shifted, for dirt trapped in the lap and for rust staining that shows water has been running. Panels that have moved apart are re-fastened, and laps are re-taped or re-sealed. At penetrations, we replace pipe boots with long-life flashings, and at curbs we rebuild the corners. Photographs mark each repaired area for the closeout record, with a count of fasteners replaced in each strip so the owner can see the scale of the work.
Skylights and roof-mounted vents deserve a second look on these roofs. Their curbs and flashings were often set with the original roof and have aged in step with it. A leak that looks like a failed fastener may be a worn skylight curb or a cracked vent boot. We trace stains to their source before swapping hardware, and we close the real opening, so the fix does not leave a new screw above an old leak.
When does a coating make sense?
A coating can seal a metal roof whose panels are sound but whose surface has weathered. A silicone coating forms a flexible, waterproof skin that bridges fasteners and small gaps, and an acrylic coating adds reflectance and a lighter-duty seal. Both depend on a clean, dry, primed surface, and both can fail if rust is not treated first. Adhesion is tested on a small area before the full roof is coated, with a tape pull or a scratch test, and the result is logged with the temperature and humidity of the day.
We prepare the roof by washing, treating rust, replacing failed fasteners and sealing laps before any coating goes on. Skipping that work means coating over leaks. The coating is applied in dry weather, in even coats, with fabric over seams and fasteners where the product calls for it. The wet season shortens the window, so we book coating work for the dry months and keep the roof protected through the rest of the year.
When is an overlay or a replacement better?
If the panels are rusted through, bent or loose beyond repair, restoring them wastes money. Two options remain. A retrofit overlay installs new panels, often standing seam, over the old roof on sleepers or a framing system, with insulation between. It avoids tear-off and keeps the building in use. A full replacement removes the old panels and puts in a new roof.
The choice rests on the structure. An overlay adds weight, and the framing must carry it, so we check the drawings and the framing in person, and we bring in an engineer when the answer is unclear. Insulation and air barriers are settled against the amended 2021 state building code and the commercial energy code together. A standing seam metal roof is the usual overlay.
How does the wet season shape the job?
Auburn collects 37.1 inches in a year, with the wettest weather in November and December and the driest in July, and Tacoma collects about 40.8 inches across roughly 155 wet days. A metal roof with failing fasteners leaks into the building with every rain, so the repair season matters. We schedule fastener work in dry stretches and place temporary sealant or tarps over the worst areas when a storm is coming.
74 mph winds hit Enumclaw in the November 2024 bomb cyclone, the highest of any Washington community. Loose metal catches that wind, so ridge caps, rake trim and the first panels at the edge are secured before anything else. Warehouse and distribution space around the Kent Valley, Auburn and Fife can have this type of roof, and an owner in Kent or Fife is welcome to send the roof plan and schedule so that both superintendents can plan the sequence, staging and tie-ins together.
Commercial Roofing Questions
How do I know if my screws are failing?
Look for rust streaks below the fasteners, raised heads, cracked washers and stains inside the building after rain. A walk with a screw gun shows how many are loose. We count and photograph them to size the job.
Is it worth re-screwing a 20-year-old metal roof?
If the panels are sound and the framing holds, yes. Re-screwing and sealing laps cost far less than replacement and can add many years. We pull-test first to confirm the framing will hold new screws.
Can you coat over rust?
Only after treating it. Loose rust is removed, the surface is primed and rust-inhibiting primer goes on before the coating. Coating over untreated rust fails early.
Will an overlay change the building's height?
Slightly, by the depth of the sleepers and insulation. We check clearances at the eave, at curbs and at walls, and extend flashings where needed. The plan lists each change.
What happens to insulation under an old metal roof?
It is often wet or compressed where leaks have run. We inspect from below where we can, cut samples and replace damaged insulation as part of the scope. An overlay with new insulation can fix the thermal weakness as well.
Send the roof plan and photographs of the fasteners
Send the roof plan, photographs of the failing fasteners and the project schedule so we can walk the sequence, staging and tie-ins with your superintendent before a number goes on paper.
