Roof Damage Repair
Seam Failure Repair in Federal Way, WA
The superintendent starts on the seam with a probe and a straight eye, walking the full length of every lap on the roof section in question. A seam that has opened once usually has neighbors in the same condition, so the walk does not stop at the one that leaked. He marks each open lap, each lifted edge and each weld that sounds hollow under a tap. In Federal Way, WA, the wet season sends water into any gap from October through March, and a split seam over insulation is how a small defect becomes a wet deck.
The sequence that follows is the same on every roof: find the seams, clean them, repair them and test them.
How do we find every open seam?
We walk each lap along its length, pressing with a blunt probe at the edge. A sound weld or bond resists. An open one gives. Seam ends at flashings, T-joints where three sheets meet, and laps near drains and penetrations get extra time, since stress concentrates there.
Each defect is photographed against a numbered plan with its length marked. We cut cores near open seams to see whether the insulation under them is wet, because water enters at a seam and travels. A commercial roof leak repair uses the same walk, but the seam walk takes in the whole section, not just the stain.
Causes get recorded beside the defects. Ponding along a seam ages the weld, so a ponding water repair may belong in the scope. Heavy foot traffic across a lap wears it out, and walk pads go in where technicians cross. Wind that flutters a sheet works a seam open from the edge, which ties the repair to wind damage repair at the perimeter.
What is cut out and what is only re-welded?
The limit depends on the system. On a thermoplastic roof, a lifted edge with sound membrane is cleaned and re-welded with hot air, and a seam that has failed along its length is capped with a strip welded on both sides. On a rubber roof, the lap is cleaned, primed and re-bonded or covered with a seam tape. On modified bitumen, a lifted lap is reheated or re-bonded and capped.
If the membrane near the seam is brittle, cracked or stretched, patching will not hold, and the limit extends to sound material. If the insulation under the seam is wet, it is cut out and replaced before the seam is repaired. Cut lines are marked in paint, and the crew leader walks them with the owner's representative.
Surface prep is the real work. The seam area is cleaned with the manufacturer's cleaner, wiped dry and checked with a moisture meter. A weld over dirt or damp membrane will look fine and fail in a season. The crew leader signs off on the prep before the welder or the adhesive comes out, and photographs the cleaned area.
What does a seam repair need on site?
A seam crew needs power for welders, walk pads, clean rags and cleaner, and a dry surface. At a retail center on Pacific Highway South the lot is live, so the lay-down area sits at its edge. An industrial building at Woodbridge, on the former Weyerhaeuser campus, has a bigger yard where truck lanes set the rules.
The crew leader walks the route to the roof, lays walk pads on the way and keeps cords off drains and seams. Tenants receive a notice naming the closed entrance, the container and the loud hours. If a rooftop unit blocks a seam, the mechanical contractor lifts or shuts it down for the hour required.
Heat tools and adhesives need care. Welders run on power from the building or a generator, and solvents are kept away from intakes. A fire watch is posted when hot work is involved. Materials come up in small loads, and rolls of cap strip are cut on the roof to fit, with scrap collected in a bag that goes back down with the crew.
How do weather and temperature affect the repair?
Seams bond best on a clean, dry, warm surface. A seam repair works around about 155 wet days a year in Tacoma, with the Green River corridor's heaviest rain in November and December and its driest month in July. A damp morning costs the day. Winter repairs wait for dry windows or go under a tent.
When a leak cannot wait, a temporary strip or tape goes on, labeled as temporary and tested with water. The permanent weld follows when the surface is dry. Next morning begins with a look at the temporary work, because cold and wind can loosen it overnight.
On long runs, the crew works from the low edge upstream, so water on the roof has a path to a drain. Each repaired stretch is tested before the next is started, and an open seam is never left across the field overnight. If a front moves in, the crew caps what is open and closes the day.
How do we repair seams at tie-ins and edges?
Seams that end at a flashing, a curb or an edge carry extra stress. We cap them with a formed piece, weld them to the flashing and seal the top with a termination bar. T-joints get a round patch with rounded corners, since a square corner lifts first. A flashing failure repair at the seam end is usually part of the same scope.
Edges matter too. A seam near an edge opens when wind gets under the sheet, and the November 2024 bomb cyclone put 74 mph on Enumclaw, the highest in Washington. We fasten the membrane at the perimeter to the manufacturer's schedule and re-secure edge metal, so the repaired seam is not asked to carry a load it cannot.
How do we test the repaired seams?
Every repaired seam is probed again after it cools, and a sample is cut and pulled where the system allows. The crew leader records the results beside each repair on the plan. Photographs are taken before, during and after, and the completed items are marked.
The closeout package lists what was repaired, with product data and test results, and it names the seams left alone and when to check them next. Owners with buildings in Kent and Auburn can use the same format for each. A roof recover is considered when seams are failing across the field, because patching one lap at a time wastes money.
The warranty shapes the repair. A manufacturer may require its own seam materials or approved applicators, and may ask for notice of repairs. The terms are read before work starts and the repair details followed, so the weld cannot become grounds for a coverage dispute. Notice, products and dates are recorded in the closeout file.
Commercial Roofing Questions
Why do seams open on a roof that is not old?
Poor original welding, movement at a deck joint, ponding or thermal cycling. We probe the whole section to find the pattern and repair the cause.
Can a seam be repaired when it is raining?
A temporary strip can. The permanent weld needs a clean, dry surface, so it waits for a dry window or goes under a tent.
How long does a repaired seam last?
A sound weld on sound membrane can last as long as the membrane. A repair on brittle material may not, which is why we check the field first.
When are failing seams a sign of replacement?
When they open across the field, when the membrane is brittle or when insulation is wet.
What does the closeout include?
Photographs, test results, product data and a map of every repaired and unrepaired seam, with the next check date.
Send the roof plan and the leak location
Send the roof plan, a photo of the stain and the location of the leak. We will walk the sequence, staging and tie-ins with your team before a number goes on paper.
