Flat roofs aren’t really flat. They’re low-slope roofs that depend on a continuous membrane and good drainage to keep water out. When water sits instead of draining, or the membrane cracks at a seam or around a vent, the leak usually shows up right below. HomeGuard Roofing repairs low-slope roofs on Dublin townhomes, home additions, patio covers, garages and small commercial buildings, and fixes the drainage problems that cause most of the damage.
Call (925) 644-8514 or call to schedule a flat roof inspection.
California’s Energy Code defines a low-sloped roof as one with a pitch of less than 2:12. At that pitch, shingles and tile don’t shed water reliably, so these roofs need a continuous membrane instead.
| System | What it is | Common problems |
|---|---|---|
| Roll roofing | Asphalt sheets, often on older patio covers and additions | Cracking, open seams, short life in heat |
| Modified bitumen (including torch-down) | Asphalt membrane modified for flexibility, heat-welded, self-adhered or cold-applied | Seam failures, blisters, surface cracking and “alligatoring” as it ages |
| TPO | Single-ply white membrane, heat-welded seams | Seam and flashing failures, punctures |
| Built-up (tar and gravel) | Layers of felt and asphalt with gravel on top | Bare spots, blisters, hard-to-find leaks |
| Coatings | Liquid-applied elastomeric or silicone layers over an existing roof | Peeling or wearing thin where water ponds |
We’ll identify your system on the inspection and repair it with compatible materials. Not every patch material bonds to every membrane.
Some water on a flat roof after rain is normal. The roofing industry generally considers water that’s still standing about 48 hours after rain to be ponding. Ponding speeds up wear on the membrane, adds weight, and finds every weak seam.
Ponding usually comes from:
If it’s gone within a day or two after rain, usually not. If it’s still there after about 48 hours, or leaves a dirt ring as it dries, the roof isn’t draining properly, and that spot will wear out first.
Asphalt-based roofs dry out under Dublin’s summer sun. The surface cracks into a pattern that looks like alligator skin. Blisters form where moisture or air is trapped between layers and expands in the heat. Both let water reach the layers below.
Most flat roof leaks start at seams, edges, and the places where something comes through the roof: vents, skylight curbs, HVAC stands and walls. Old patches covered with sealant often hide the real problem.
On West Dublin additions, a low-slope roof often ties into the original shingle roof. That transition is a classic leak point if the two weren’t flashed together correctly.
Raised skylight curbs and AC equipment stands need their own flashing. When they’re sealed only with mastic, they leak.
For leaks that are hard to pin down, especially on a newly installed flat roof, see roof leak detection.
A coating can extend the life of a roof that’s still sound and draining well. It won’t fix ponding, wet insulation, open seams or a failing membrane, and coatings applied over those problems usually peel. We’ll tell you if your roof is a good candidate.
| Option | When it fits |
|---|---|
| Repair | Damage limited to seams, flashings or a small area; membrane otherwise sound |
| Coating | Sound, dry roof that drains well; you want to extend its life |
| Recover (new membrane over the old) | Existing roof is dry and code allows another layer |
| Replace | Widespread cracking, wet insulation, repeated leaks, or ponding that can’t be fixed without rebuilding slope |
On many Dublin townhomes, the roof is a shared or common-area element, and the HOA, not the individual owner, is responsible for repairs. Check your CC&Rs before scheduling work. We work with homeowners, HOA boards and property managers on shared roofs; see HOA and townhome roofing.
Small repairs may not need a permit; recovering or replacing a low-slope roof generally does. California’s Energy Code has cool-roof and insulation rules for some low-slope re-roofs, depending on climate zone and building type. Dublin is in Climate Zone 12. We confirm the requirements for your roof before quoting materials.
| Job | Typical range in Dublin |
|---|---|
| Seam or flashing repair | Range TBD |
| Skylight or curb re-flash | Range TBD |
| Section replacement with deck repair | Range TBD |
| Drainage correction (drain, scupper, tapered insulation) | Range TBD |
| Coating on a sound roof | Range TBD |
Price depends on roof size, membrane type, access, deck damage, drainage work, and whether rooftop equipment has to be moved.
The home: A 1960s West Dublin ranch with a later family room addition under a low-slope roof.
What we usually find: The low-slope membrane wasn’t properly flashed where it meets the original shingle roof, so water runs back under the shingles at the transition.
The fix: The transition rebuilt with proper flashing, shingles relaid above, and the low-slope section’s seams checked and repaired.
The home: A townhome near Dublin Boulevard.
What we usually find: Water standing for days near a drain set slightly higher than the surrounding roof, with alligatoring in the ponding area.
The fix: Drain reset, low area built up toward the drain, damaged membrane replaced. Coordinated with the HOA because the roof is a shared element.
Angela M.Downtown Dublin · Flat roof repair“Our townhome’s flat roof section was ponding and leaking into the living room. They fixed the drainage, replaced the bad section, and tested it with water before they left. Dry ever since.”
It should be gone within about 48 hours. Water standing longer than that is ponding and points to a drainage or deck problem.
It depends on the building, HOA rules and budget. TPO and modified bitumen are both common. TPO’s white surface reflects heat, which matters in Dublin’s summers and may matter for Energy Code compliance. We’ll explain the trade-offs for your roof.
Many flat roofs can be repaired if the damage is limited to seams, flashings or one area. Widespread cracking, wet insulation or ponding that can’t be fixed without rebuilding the slope usually means replacement.
Raised skylight curbs need their own flashing tied into the membrane. If they were only sealed with mastic, they leak once the sealant dries out.
Often the HOA, if the roof is a common element under your CC&Rs. Check your documents or ask your property manager before hiring anyone.
Torch-applied roofing uses an open flame, so it requires trained installers and care near walls, eaves and vents. Self-adhered and cold-applied modified bitumen are alternatives that avoid the torch. We’ll recommend the right method for your roof.
Most flat roof leaks trace back to water that isn’t getting off the roof. Call HomeGuard Roofing at (925) 644-8514 or call to schedule a flat roof inspection and we’ll show you where the water goes, and how to fix it.
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