TPO Over an Existing Roof: When It Works — Step by Step
What to do about a TPO roof in the Harbor Area in the first forty-eight hours, and what to leave until Monday.
After a storm the useful work happens in the first two days, and most of it is documentation rather than repair. This is what to do about a TPO roof in the Harbor Area once the wind drops.
What actually matters
Punctures are the most common TPO failure by a wide margin, and most of them are made by people rather than weather. Rooftop trades drop tools, drag equipment and set ladders down on a membrane that is perfectly capable of resisting rain and not at all capable of resisting a dropped screwdriver.
What to do in the first forty-eight hours
Document before you touch anything: wide photographs to establish the property, then close photographs of each item of damage, all dated. Weld testing is the item to insist on. A probe run along every seam while the crew is still on site costs nothing and finds the cold welds that would otherwise be discovered by a tenant in December. A tarp fixed through sound covering creates damage that was not there before.
How the Harbor Area changes the answer
Humidity stays high, salt is constant, and industrial fallout settles on top of both. Flat and low-slope roofs dominate the commercial stock here, and a membrane that would give twenty years in a dry inland setting can give noticeably less with that combination working on it every day. Much of the building stock is older commercial and industrial with large low-slope areas, parapets, and rooftop plant that gets walked on regularly.
What we look at on an inspection
- Seam integrity, probed along the full length rather than spot-checked
- Punctures and abrasion, especially on traffic routes to rooftop plant
- Membrane shrinkage and any resulting tension at the perimeter
- Flashing and termination bar at every wall, curb and upstand
- Drain sumps and clamping rings, checked and clear
- Fastener plates showing through the membrane surface
- Weathering and chalking of the surface, particularly on exposed elevations
Common questions
Should I get a tarp on it straight away?
Only once it is photographed, and only if it can be fixed without putting new holes through sound covering. A badly fixed tarp creates damage that was not there before.
How soon do I need to report it?
Check your policy, because most impose a reporting window. Reporting early costs nothing and protects the claim.
The honest summary
TPO is a good system installed properly and an expensive mistake installed quickly. Seams and punctures decide its life, so protect the surface and test the welds. In the Harbor Area the thing to watch is membrane condition around rooftop plant, parapet terminations, and every drain and scupper on the roof.
Free inspection, drone photography where access is difficult, and a written estimate with deck repair priced per sheet. No obligation.