| Quick Answer
October is the month to look up. Most of what causes a winter leak in Contra Costa is visible from the ground in autumn and inexpensive to fix in autumn. The same repair in January costs more, takes longer to schedule, and has usually done damage inside by the time anyone gets to it. |
The seven-point check you can do from the ground
You do not need to get on the roof, and you should not. Stand back far enough to see the whole plane, use binoculars or a phone camera at full zoom, and work through these.
- The ridge and the edges. Lifted, curled or missing shingles show first at the ridge line and along the rakes and eaves, because that is where wind gets underneath. A single lifted tab is a repair. A pattern across one whole plane is usually age.
- Valleys. Where two roof planes meet, water concentrates. Look for dark staining, debris dammed in the valley, or metal that has rusted through at the fold.
- Flashing. At the chimney, at any wall junction, around skylights, and at vent penetrations. Flashing that has pulled away, lifted at the edge, or been “repaired” with a smear of sealant is the single most common leak source and the cheapest thing on this list to put right.
- The gutters. Granule build-up in the gutter is shingle surface that is no longer on the shingle. A handful of grit is normal after a new roof. A sludge of it on a fifteen-year-old roof means the surface is going.
- The roof line itself. Sight along the ridge. Any sag, dip or wave is structural and needs looking at properly rather than being roofed over.
- Fascia and soffit boards. Soft, stained or peeling fascia means water has been running where it should not, usually from blocked or badly pitched gutters.
- Inside the attic, in daylight, lights off. Pinholes of daylight are holes. Dark staining on the underside of the sheathing is a leak that has been happening for a while. Compressed or stained insulation marks where the water lands.
Photograph anything you are unsure about. A roofer can tell a great deal from a photograph and it saves a trip for both of you.
Repair or replace, honestly
The honest rule is about pattern, not about any single defect.
| Points to repair | Points to replacement |
|---|---|
| One or two damaged areas on an otherwise sound roof | Damage distributed across more than one plane |
| Flashing failure at a specific penetration | Widespread granule loss and brittle, curling shingles |
| Storm damage of recent and obvious origin | A roof at or past its expected service life |
| A roof well within its service life | Multiple previous repairs layered over each other |
| Sound decking underneath | Any sag, soft decking or structural movement |
| A roof you intend to replace within a few years anyway, needing to get through this winter | Planning to add solar, an ADU tie-in or a roof-mounted system |
One point worth making plainly because it saves people money: if a roof is genuinely at end of life, repairing it twice before replacing it costs more than replacing it once. And if you are planning solar or an addition that ties into the roofline within the next few years, do the roof first. Removing and reinstalling a solar array to replace a roof underneath it is a cost nobody enjoys explaining.
Siding, and the thing people get wrong
Siding failures show up as peeling paint that returns within a season, soft boards at ground level, visible gaps at joints and butt ends, and staining below windows. The last one usually means window flashing rather than siding.
The common mistake is treating siding as a finish problem. It is a water management problem. Behind the boards there should be a weather-resistive barrier, correctly lapped so water running down it is directed outward rather than inward, with flashing integrated at every opening. Siding installed over a compromised barrier looks fine for several years and then does not.
Worth knowing locally: Walnut Creek lists vinyl siding installed over existing siding as a simple scope, but notes that if the existing siding is removed first a full building permit is required and it advises checking with the planning division first to confirm vinyl is allowed on the building at all. Different Contra Costa cities treat this differently, so ask before you buy material.
Gutters and drainage, which cause more damage than roofs do
Unglamorous and frequently the actual culprit. Blocked gutters overflow at the fascia and rot it. Downpipes discharging at the base of a wall saturate the soil against the foundation. On the hillside lots common in Lafayette, Orinda and parts of Pleasant Hill, uncontrolled roof water finds the path of least resistance and that path is often somebody’s crawlspace.
- Clear the gutters before the first sustained rain, not after.
- Check the fall. Water should move, not pool.
- Extend downpipes away from the building and discharge them somewhere that drains.
- Watch where water goes during the first real storm. Twenty minutes outside in the rain tells you more than any inspection.
Why October specifically
Three practical reasons. Materials go on better in dry, mild conditions adhesive strips on shingles need warmth to seal properly, and a roof installed in cold wet weather may not bond as it should until the following spring. Trades have availability in October that disappears the moment the first storm generates emergency calls. And a small defect found now is a small job, whereas the same defect found in January is a leak, a ceiling, insulation, and whatever was underneath it.
What exterior work costs
Exterior scope varies more than almost anything else, because the condition of what is underneath is invisible until the covering comes off which is precisely why we do not publish a flat per-square figure.
Our cost estimator handles exterior work within a wider project scope and asks about the complications that matter here, including tying into the roofline and foundation work. It gives you a planning range in about thirty seconds, no email required. A range at that stage includes demolition and haul-off, permits and plan check for one jurisdiction, materials at your chosen finish level and project management through to final clean. It cannot know the condition of the decking under your shingles until someone looks.
For a roof specifically, the honest answer is that a proper inspection costs you nothing and converts the guess into a scope. That is a better use of a phone call than any number we could publish here.
Frequently asked questions
When is the best time to replace a roof in Contra Costa County?
Late spring through autumn, with October being the last comfortable window before the wet season. Shingle adhesive strips seal better in dry, mild weather, and trade availability is better before the first storms generate emergency work.
How do I know if my roof needs replacing or just repairing?
Look for pattern rather than individual defects. Damage on more than one plane, widespread granule loss, brittle or curling shingles, multiple layered previous repairs, or any sag in the roof line all point to replacement. Isolated damage on an otherwise sound roof is a repair.
Do I need a permit to replace a roof?
Generally yes. Re-roofing is listed among the work requiring a building permit in Contra Costa cities. Your contractor should pull it and manage the inspection.
What causes most winter roof leaks?
Flashing failures at chimneys, wall junctions, skylights and vent penetrations, far more often than failures in the field of the roof itself. It is also the cheapest category to put right if you catch it in autumn.
Can I put new siding over old siding?
Sometimes. Walnut Creek, for example, treats vinyl over existing siding as a simple scope but requires a full building permit if the existing siding is removed first, and advises confirming with planning that vinyl is permitted on the building. Rules vary by city, so confirm before buying material.
My gutters overflow. Is that a roof problem?
Usually not. It is normally blockage, insufficient fall, or undersized downpipes. It becomes a roof problem when the overflow has been rotting the fascia for a few seasons, which is why it is worth fixing early.
