Dry rot and other wood damage in San Francisco homes: telling fungus from termites, finding the moisture and what comes next.
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Dry rot is wood decay caused by fungus, and it needs moisture to start. It is not the same as termite damage, though the two often sit side by side. In California the Structural Pest Control Board covers fungus and dry rot under Branch 3. San Francisco Pest Control connects San Francisco callers with a technician who inspects first.
The name is a trap. Dry rot sounds like something that happens to dry wood, but the fungus behind it needs moisture to take hold, which is why the damage so often turns up at a window sill that never quite dries, a fascia board under a clogged gutter, or a deck post sitting in damp soil. By the time the wood looks dry and crumbly, the water that started it may be long gone.
A coastal city with sea fog and wet winters gives exterior wood a lot to put up with. This page explains how a technician tells fungus damage from termite damage, how the cause is traced, what repair involves and where pest control stops and carpentry starts. San Francisco Pest Control is a call line that connects you with an independent local pest-control company; phones are answered 24/7, and a same-day visit is offered only when a technician is free.
Do not cut into load-bearing framing, a sill plate or floor joists yourself. Soft wood can hide the support of a floor or a wall. Keep people off decks and stairs that move underfoot.
A technician checks suspect wood with a probe and, where available, a moisture meter. The aim is to learn how far the decay goes and whether the wood is still wet.
The next question is whether the damage comes from fungus, termites or both. Pellets, mud tubes or galleries point to insects, while crumbling and cube-shaped cracking point to decay.
The technician looks at what has been feeding the damage: roof edges, gutters, flashing, window caulk, plumbing, sprinklers or a crawl space that stays damp. Without that, repaired wood can fail again.
You receive a description of where the damage is, what looks active and what looks old. If the property is being sold, ask how the report would be used.
Pest control can identify and treat. Cutting out and replacing rotted framing is usually carpentry. A technician can say which pieces look structural so you can call the right trade.
After repairs, ask for a recheck of the same spots and a plan to keep them dry. A fixed gutter and a clear vent often do more than a product.
No San Francisco price for dry rot or wood repair was confirmed in sources, so no dollar figure is printed. These are the things that move a quote.
| Job | Typical range | What it includes |
|---|---|---|
| Inspection and report | Set by scope | A single window differs from a whole building; the report is part of the price conversation |
| Amount of wood affected | Set on inspection | A short length of trim is not the same as a section of sill plate or floor joist |
| Structural importance | Varies by site | Framing that carries load needs more care and often permits or an engineer |
| Moisture repair | Often a separate trade | Roofers, plumbers and gutter contractors may be needed alongside the carpenter |
| Access | Varies by site | Crawl spaces, high eaves and tight lot lines add labour |
These are cost drivers, not prices. A technician confirms what a pest-control visit costs before any work begins; carpentry is usually quoted by the contractor.
No. Dry rot is decay caused by a fungus that needs moisture, while termite damage is made by insects eating the wood. They can look alike from a distance and often occur together. A technician looks for pellets, mud and tunnels to tell them apart.
Fungus decay tends to make wood soft, dark and cracked across the grain, sometimes with a musty smell. Termite damage tends to follow the grain and may include pellets, mud or thin paper-like layers.
Since a repair can fix one and leave the other, the report should say which was found where. Our termite inspection page covers how that report is built.
Persistent moisture causes it: a leak, a gutter that spills, flashing that fails, a window with open caulk, or soil and plants against wood. Coastal fog can contribute by keeping exterior wood damp, though the cause on any building is the specific water path.
San Francisco has dry summers, wet winters and fog that can linger. We do not have a figure for how that shortens the life of paint or wood, so we describe it as one more thing exterior surfaces face, not as a guarantee about any house.
Drainage matters more than weather alone. Downspouts that end at the foundation, planters against siding and sprinklers that wet the wall all keep wood damp for longer than it would be otherwise.
In California, the Structural Pest Control Board's Branch 3 covers termites, wood-boring beetles, dry rot and fungus. So an inspection may report on decay as well as insects. Repairing the damaged wood is generally carpentry, not pest control.
Ask the company what its report will cover and what it leaves out. Some reports describe visible and accessible areas only, and a closed wall is not part of that.
If you are buying or selling, ask your agent about the report and who handles the repair estimate.
Keep water away from wood. Clear gutters, point downspouts away from walls, repaint and recaulk exposed joints, and keep soil and mulch below the siding line. Check places that stay damp, such as under sinks and around windows, and fix leaks quickly.
Look at the crawl space if you have one. Blocked vents, standing water and bare damp soil can keep the sub-floor wet for months.
A flashlight and a screwdriver, used gently on sills, deck posts and fascia, find more than a glance from the ground. Write down anything soft and tell the technician.
Caused by a wood-decay fungus that grows where moisture persists. The wood loses strength, often cracks into cubes and darkens. The fix is to stop the moisture, remove the soft wood and replace it, and sometimes treat the surrounding timber.
Tunnels made by termites follow the grain and may be packed with soil or pellets. Termites need their own treatment, covered on our subterranean termite control and drywood termite control pages.
A damp board that has gone soft is also easier for termites to enter, and a building can hold both. A technician maps each separately, since each needs a different response and often a different tradesperson.
Fog, wet winters and dry summers are the character of the coast here, and exterior wood takes the brunt: window sills, eaves, trim, porch steps and the bottoms of door frames. This is background, not a prediction. The rot you find on a specific building will follow its own water path.
Older San Francisco buildings were often built with wood details that rely on paint to keep water out. When the paint fails at a joint, water gets in and stays. Bay windows, wooden stairs and exterior cornices are common places to find soft spots, and a technician checks them carefully.
Hillside and attached buildings add details of their own. Retaining walls and soil against foundations can hold water against framing, and shared walls can hide leaks until a stain appears next door. If a leak is in a neighbouring unit or the building's common areas, the owners or association may need to act.
Bay windows, stairs and decks cover much of what a technician checks on the outside. Inside, the places to watch are the ones that see water: under kitchen and bathroom sinks, around tubs and showers, and at the base of exterior doors. If a stain keeps coming back after a wipe, treat it as a question about where the water goes.
Call any hour and explain what is going on. You get a clear price before any work starts.
Not sure if you're covered? Check your ZIP code.
Termite inspection for San Francisco houses and flats: swarms, sales reports and what a technician looks at.
Western subterranean termites in San Francisco buildings: how a technician finds the soil link and treats the structure.
Drywood termites in San Francisco attics, trim and roof framing: how they are found and the options for treating them.
We could not source a San Francisco or Bay Area pest control price, so this guide prints no dollar figure.
Only two pest timings are sourced for San Francisco: western subterranean termites swarm in calm sunny spells right after the first autumn rains, and winter rain runs November to March.
According to UC IPM, western subterranean termites swarm in calm, sunny periods right after the first autumn rains, and the effect is especially pronounced in the San Francisco Bay Area.
A Wood Destroying Pests and Organisms report is the written findings of a California Branch 3 inspection: termites, wood-boring beetles, dry rot and fungus.
Dry rot is a wood-decay fungus, not an insect, and it needs moisture to grow despite the name.
Press a screwdriver into it. Wood that sinks in, crumbles into cubes or feels spongy likely has decay. Wood that looks fine but sounds dull when tapped needs a closer look from a technician.
The fungus grows where moisture and wood are present, so it can move along damp timber. It is stopped by removing the moisture and replacing the damaged wood, not by painting over it.
Paint hides the surface but does not restore strength and can trap moisture. If the wood is soft, it is better to have it checked and, where needed, replaced.
Pest control identifies and treats insects and reports on fungus. Replacement of rotted wood is typically done by a carpenter or contractor, and a technician can say what looks structural.
Damp air can keep exterior wood wet longer, but rot starts where water gets in and stays. The fix is local: gutters, flashing, caulk, drainage and ventilation.
San Francisco Pest Control is a call line that connects you with an independent local pest-control company. Phones are answered 24/7, and a same-day visit is offered only when a technician is free. Call (855) 974-4733 and describe where the wood is soft.