Flat Roof & Skylight Repair

Flat roofs fail at details and drainage, not in the field

A torch-down, TPO or coated-foam field can look tired for years and still shed water fine. What actually leaks is the perimeter and the interruptions: seams and laps, the base flashing where the flat meets a wall or the tile above it, drains and scuppers, parapet caps, and every penetration — vents, condensate lines, HVAC curbs, skylight curbs, satellite mounts.

Drainage is the second half of the story. Low-slope roofs are designed to move water, not hold it. Once a section ponds — because the framing sagged, an insulation board compressed, or a drain is partly blocked — standing water sits on a seam for days after a storm, drives UV degradation faster than anywhere else on the roof, and eventually wicks through. In San Diego County most ponding damage happens in the few weeks a year it actually rains hard, then bakes all summer.

On the coast, in Oceanside, Carlsbad, Encinitas and Imperial Beach, salt air attacks the metal in exactly these locations: drain rings, scupper boxes, counterflashing, and the fasteners in the termination bar. Inland in El Cajon, Santee and Escondido, surface temperatures on a dark flat roof drive expansion and contraction that opens seams and pulls terminations loose.

Repairing torch-down, TPO and foam correctly

Every membrane wants its own compatible repair. Torch-down (modified bitumen) is repaired with heat-welded modified patches lapped shingle-fashion over the flow, not with a bucket of cold roof cement. TPO is a single-ply thermoplastic and must be hot-air welded with TPO material — solvent-based cement will not weld it and asphalt products destroy it. Sprayed polyurethane foam is cut out, refoamed and re-coated with a compatible acrylic or silicone.

Using the wrong material is one of the most common failures we find on flat roofs in the county, usually where a handyman patch was made. It looks fixed for a season, then delaminates and leaks in a wider area than before. Where we find that, we cut the incompatible patch out entirely rather than adding another layer on top of it.

We also correct the geometry when that is the actual problem: adding tapered insulation or a cricket to move water off a low spot, re-pitching a small area, clearing and re-flashing a drain, or enlarging a scupper so a parapet roof can actually empty.

Skylights: reseal, reflash, or replace

Skylights leak in three distinct ways and the fix is different for each. The dome or glass unit itself can fail — a cracked acrylic bubble, a fogged or failed insulated glass seal — and that means replacing the unit. The curb flashing can fail, which is where most 'skylight leaks' actually live: the step and head flashing where the curb meets tile or shingle has corroded or was never woven in properly. Or the perimeter sealant on an older acrylic dome has simply chalked out in the coastal UV.

We diagnose which of the three it is before quoting, because resealing a skylight whose curb flashing is gone just moves the leak. Old acrylic domes on 1980s Carlsbad and Encinitas homes are frequently past saving; a modern curb-mount or deck-mount unit with new flashing costs more than a reseal and stops the annual repeat visit.

Condensation is the fourth possibility and it is not a leak at all: cold glass in a warm humid bathroom drips exactly like a leak does. The attic and moisture check tells us which one you have before you pay for anything.

Is a coating a real repair?

Sometimes — and only in the right place. A silicone or acrylic coating over a sound, properly prepped, correctly draining flat roof is legitimate maintenance that adds UV protection and years of life. Sprayed over ponding water, open seams, wet insulation or a failed membrane, it is paint over a problem and traps moisture underneath, where it quietly rots the deck.

We say which of those two situations you have. If the field is sound and the details need work, we repair the details and coating becomes a reasonable option. If the membrane is saturated, no coating fixes it.

What moves the price

Membrane type

TPO welding, torch-down and foam each need their own materials and equipment.

Wet insulation

Saturated board or foam has to come out; that expands the repair area.

Drainage correction

Re-pitching a ponding low spot or reworking a drain is more than a patch.

Skylight scope

A reseal, a reflash and a full unit replacement are three different prices.

Where we do this work

We repair low-slope roofs and skylights across the county — mid-century flat roofs in San Diego, La Mesa and El Cajon, coastal additions and beach cottages in Oceanside, Carlsbad, Encinitas and Coronado, and the flat patio sections on tile-roofed homes in San Marcos, Vista and Escondido.