Roof Repair
Flat roof repair in San Jose for leaks and ponding
On a flat roof the leak is usually where the water sits. We repair the membrane properly, not with a bucket of roof cement, and fix the reason it is pooling there.
What we treat
- Concrete and clay tile
- Composition shingle
- Flat, torch-down and TPO
- Spray foam
- Standing seam metal
Quick answer. Flat roof repair in San Jose means cutting out and re-welding split TPO or PVC seams, torching in new plies over blisters and cracks on modified bitumen, repairing built-up roofs and recoating spray foam, and then correcting the ponding or blocked drain that caused the failure. Most repairs are done in one visit.
Updated September 2026
The job
Why flat roofs fail where they do
Water that sits for days after a storm softens membranes, opens seams and finds every pinhole. Most flat roof leaks we trace are at a seam, a blister, the edge of a drain, or a curb around rooftop equipment.
Roof cement slapped over a crack stops water for a few weeks and makes the next repair harder. We cut out and replace damaged membrane with the same system.
What happens after you call
How a flat roof repair runs
- 1
Find the water
Leak traced from inside, then on the roof.
- 2
Open the area
Damaged membrane cut back to sound material.
- 3
Dry and check
Insulation and deck checked for moisture.
- 4
Repair in kind
Welded, torched or foamed with the same system.
- 5
Fix the drainage
Drain cleared or low spot built up.
- 6
Water test
Area flooded and checked before we leave.
Warning signs
Signs a flat roof needs repair
- Water still standing two days after rain
The drainage has a problem.
- Bubbles or soft spots
Moisture is trapped under the membrane.
- Cracked or chalky surface
Coating or cap sheet has worn thin.
- Open seams or lifted edges
Laps and flashing are failing.
- Stains on top-floor ceilings
Water is already getting through.
- Patches on patches
The roof is near the end of repair life.
Jobs this page covers
Ponding water and blisters
Blisters form where moisture trapped under the membrane expands in the sun; ponding forms where the deck sags or the drain is blocked. We cut open blisters, dry them, and patch with the same material. Ponding gets traced to its cause: a clogged drain is cleared, a low spot is built up with tapered insulation or a cricket, and a sagging deck is noted for repair before it gets worse. Water still standing two days after rain is where we recommend drainage work.
Torch-down and modified bitumen seams
Modified bitumen fails at its laps, where the torched seam lifts or cracks with age. The repair cleans and primes the area, torches a new ply well past the damage in every direction, and seals the edge with granules to match. Cracks around parapets and curbs get new base flashing. We keep a fire watch during and after torch work, and use cold-applied materials near wood trim or vents. Old roof cement is scraped off first, since new plies will not bond to it.
TPO and PVC membrane patches
Single-ply membranes are repaired by cleaning the area and hot-air welding a patch of the same material over it, which bonds as strongly as the original seam. Punctures from foot traffic and dropped tools, split field seams and loose flashing at curbs are all repaired this way. Tape and sealant patches on single-ply are temporary; if we find them, we replace them with welded ones. Aged membrane is cleaned with a membrane cleaner first, because a weld on dirty sheet looks fine and peels in a season.
Foam roof cracks
Spray foam roofs crack where the protective coating has worn thin and the sun reaches the foam. Birds peck at exposed foam too. We cut out damaged foam, fill it with new foam or a foam-compatible sealant, and recoat the area so the sun cannot reach it. When the whole surface is chalky and thin, the right repair is a full recoat, and we price that alongside the spot repair. Foam that has taken on water is removed down to dry foam before refilling.
What we see on San Jose roofs
Many of the flat roofs we repair are on mid-century homes in Willow Glen, where roughly 350 Eichlers were built with flat and nearly flat roofs. Most Eichler roofs are spray foam or built-up systems with a service life of ten to twenty years depending on maintenance, and neighborhood design guidance in Fairglen favors foam to keep the low profile. That makes recoats, foam crack repair and built-up patching a regular part of our flat roof work there.
Water sitting on the roof days after the rain? Call us before it finds a seam.
(669) 259-7490Cost
What a flat roof repair costs depends on
Flat roof repairs are priced on the spot once the membrane is opened and the cause is known.
- Membrane type Welding, torching and foam work use different crews and materials.
- Size of the damage Patches are sized well past the damaged area.
- Wet insulation Soaked insulation under a leak must be cut out.
- Drainage fixes Crickets or tapered build-up add material.
- Curbs and edges Flashing repairs at equipment and parapets.
- Access Ladders, hatches and equipment on the roof.
Brands we install and service
FAQ
Questions we get asked
Most leaks are repairable. Widespread wet insulation or constant ponding is when replacement makes more sense.
Yes: foam, built-up and single-ply, including recoats.
Only as an emergency stopgap. It fails quickly and complicates the proper repair.
A repair made with the same system lasts as long as the membrane around it.
Often, by clearing drains and building up low spots with crickets or tapered insulation.
Same category
Related roofing work
Shingle Roof Repair
Torn, missing and curling shingles, nail pops and ridge caps on composition roofs.
Learn moreTile Roof Repair
Cracked and slipped tiles, failed underlayment and valley repairs on concrete and clay.
Learn moreRoof Flashing Repair
Chimney, wall, skylight and vent flashing rebuilt so the joint stops leaking.
Learn moreSkylight Leak Repair
Curb, flashing and seal failures on skylights and sun tunnels.
Learn moreGet the flat roof leak fixed properly
Tell us the roof type if you know it and where the water shows. We repair it in kind and fix the drainage behind it.