Wood Rot & Dry Rot Repair in San Francisco, CA

San Francisco's marine fog belt and salt air create a year-round environment where wood rot and dry rot repair is not a seasonal concern but a structural necessity. Our older housing stock, from Victorian and Edwardian homes to 1920s stucco-over-wood rows and mid-century tracts, relies on wood framing that faces constant moisture exposure. When rot takes hold in sill plates, floor joists, rim joists, or exterior trim, it weakens the structure and spreads quietly until visible damage appears. We cut out decayed wood, treat surrounding framing, and rebuild with rot-resistant lumber, a permanent repair that restores integrity without unnecessary replacement. This is the work that matters in San Francisco.

Why Wood Rot and Dry Rot Repair Matters in San Francisco

The fog and salt spray that define San Francisco's climate keep exterior wood perpetually damp. Dry rot (despite its name) thrives in wood that stays moist for extended periods, breaking down the cellular structure from the inside. Unlike termite damage, which leaves galleries and frass, dry rot spreads through the wood grain and can compromise load-bearing members, floor joists, and structural sill plates without obvious signs until the damage is advanced. Winter rains and spring storms expose leaks that have been quietly rotting framing for months. Addressing rot early prevents costlier structural repairs and keeps your home safe and level.

Rot in sill plates and rim joists allows water to migrate upward into wall cavities and floor systems, compounding damage over time.
Decayed floor joists or subfloor create soft spots, bouncy floors, and eventual sagging that worsens settlement and door sticking.
Exterior trim and fascia rot allows water to penetrate behind siding and into the framing cavity beneath.
Untreated rot spreads to adjacent sound wood, doubling the repair scope and cost within a few years.

Early detection and repair preserve the integrity of your framing and prevent exponential cost growth.

Key info: San Francisco's Department of Building Inspection requires permits for any structural repair involving load-bearing walls, beams, joists, or exterior work that alters the building envelope. We work with the DBI requirements and help coordinate inspections as needed. See the SF Department of Building Inspection for specific thresholds and scope requirements.

How We Repair Wood Rot and Dry Rot in San Francisco Homes

Our repair process is straightforward and field-tested. We start with a detailed inspection to map the extent of decay, identify the moisture source, and determine which wood must be removed and which can be treated and preserved. We remove decayed framing and trim carefully, install temporary support if needed for load-bearing members, treat surrounding sound wood with a wood preservative, and rebuild with pressure-treated or naturally rot-resistant lumber sized to match the original framing. The result is a permanent repair that matches the structure's original capacity.

We inspect the affected area, probe for decay depth, and identify the moisture source (leak, poor drainage, condensation, or splash-back).
We remove decayed wood in sections, taking care to avoid unnecessary demolition of sound material.
We treat exposed sound wood with a wood preservative to arrest any incipient decay.
We install new framing, trim, or siding in rot-resistant lumber, sized and fastened to match the original structural intent.
We address the moisture source, whether that means rerouting gutters, sealing cracks, improving drainage, or repairing the leak that started the rot.

This methodical approach means your home is structurally sound and the rot does not return.

Local example: A Victorian in the Mission District with original 1890s redwood sill plates showed rot in the front bay window base where water was splashing back from the foundation. We removed the decayed sill, treated the rim joist and subfloor above, and installed new pressure-treated Douglas fir sill plate with proper flashing and drainage. The bay window is now level and dry, and the repair will outlast the original.

Wood Rot Repair Methods and Approaches

Approach	Description	Best for
Localized removal and rebuild	Cut out decayed section, treat surrounding wood, install new lumber matched to original size and species.	Rot confined to one framing member or trim section, moisture source identified and controlled.
Sistering	Install a new member alongside a partially decayed joist or beam, bolted and fastened to share the load, allowing the weakened original to remain in place.	Moderate decay in load-bearing joists or beams where full replacement would require extensive temporary support and ceiling work.
Complete member replacement	Remove the entire decayed framing member, install temporary support, and install new lumber to match original dimensions and grade.	Extensive decay affecting the majority of a joist, beam, or load-bearing member, or decay near critical connections.
Exterior trim and fascia replacement	Remove rotted trim, fascia, or soffit, treat framing behind it, and install new exterior-grade lumber with proper flashing and paint.	Rot in overhangs, eaves, trim boards, or fascia that does not affect framing but allows water to penetrate further.

Each approach preserves what is sound and replaces only what must be replaced, keeping your repair cost realistic and your home structurally intact.

Wood Rot and Dry Rot Repair Cost in San Francisco: What to Expect

The cost of wood rot repair in San Francisco depends on the extent of decay, the location of the damage, and the repair method. A small, localized rot repair in exterior trim might start at $650 and rise quickly if the damage extends into framing or affects multiple members. A sill plate or rim joist repair, which involves more extensive work and possible temporary support, typically runs $1,500 to $3,500 or more depending on access and the length of framing affected. Large structural repairs involving sistering or full joist replacement can exceed $5,000 and may require engineering and permits. The best approach is to get a detailed estimate that breaks down removal, treatment, lumber cost, labor, and any permits or inspections required.

Several factors affect the final price. The depth and spread of decay determines how much wood must be removed. Access and location matter greatly: rot in a basement sill plate is easier to repair than rot in a second-story overhang or behind living spaces. Load-bearing status affects cost because structural repairs require temporary support during work. Moisture source identification and repair adds cost but prevents the rot from returning. Permits and inspections are required for structural work and add timeline and cost. Material choice (pressure-treated lumber, naturally rot-resistant species like redwood or cedar, or engineered lumber) affects price and longevity.

We recommend getting two or three estimates from experienced carpenters. A low estimate that glosses over the moisture source or proposes cosmetic patching instead of real repair will cost you more in five years when the rot returns. Our estimate is free and includes a detailed breakdown of scope, materials, timeline, and any permits required. See our full pricing overview for typical ranges and call (628) 285-5429 to schedule an inspection.

Wood Rot and Dry Rot Repair Near Me: What San Francisco Homeowners Should Know When Hiring

Choosing the right carpenter for wood rot repair means understanding what to look for beyond price. A qualified carpenter brings field experience, knowledge of San Francisco's older housing stock and its common pathologies, and a commitment to permanent repair rather than cosmetic patching. Here are the essentials to evaluate.

Verify that the carpenter is fully insured and carries general liability and workers compensation coverage, protecting you if an accident occurs on your property.
Ask for references from recent wood rot or structural repair jobs and follow up with homeowners about the quality of work and whether the repair has held.
Confirm that the carpenter understands San Francisco Building Code and DBI permit requirements for structural work, and that they will coordinate with the building department as needed.
Request a detailed written estimate that identifies the decay, explains the repair method, lists materials and labor, and addresses the moisture source.
Understand that structural repairs affecting load-bearing members may require a licensed structural engineer to size beams or joists and sign off on the design; the carpenter can help coordinate this.
Check whether the carpenter has experience with older homes and their quirks: settled foundations, out-of-square framing, and original millwork that must be respected and repaired, not demolished.

A carpenter who explains the problem clearly, proposes repair before replacement, and stands behind their work is worth the call. Contact us at San Francisco Carpentry for a free estimate and to discuss your specific situation.

Wood Rot & Dry Rot Repair in San Francisco: Pricing Guide

Service	Price	Details
Small exterior trim or fascia rot repair	Starting at $650	Localized decay in trim, fascia, or soffit with no framing involvement
Sill plate or rim joist repair	Starting at $1,500	Includes removal of decayed sill, treatment, new pressure-treated lumber, and flashing
Floor joist or beam sistering or replacement	Starting at $2,500	Depends on joist length, load-bearing status, and whether temporary support is required
Complex or large-scale structural rot repair	On estimate	Multiple members, engineering, permits, and moisture remediation included
Travel and estimate	Free estimate	Response within 24 hours at (628) 285-5429; travel included in San Francisco and surrounding areas

Indicative pricing, free personalized estimate within 24h at (628) 285-5429.

Frequently asked questions: Wood Rot & Dry Rot Repair in San Francisco

How much does wood rot repair cost in San Francisco?

Wood rot repair in San Francisco starts at $650 for small exterior trim damage and rises to $1,500 to $3,500 for sill plate or rim joist work. Structural repairs involving floor joists, beams, or multiple members can exceed $5,000. The cost depends on the extent of decay, whether framing is load-bearing, access difficulty, and whether permits are required. We provide a free detailed estimate that breaks down all costs.

What is the difference between dry rot and wet rot?

Dry rot (wood decay fungus) thrives in wood that stays moist but not saturated, breaking down the cellular structure and leaving the wood brittle and prone to cracking. Wet rot occurs in wood that is consistently saturated and typically softens the wood fibers. Both are serious and require removal and replacement of the affected framing. The repair method is the same: cut out the decay, treat surrounding wood, and rebuild with rot-resistant lumber.

How long does a wood rot repair take?

A small trim or fascia repair typically takes one to two days. A sill plate repair or single joist sistering usually takes three to five days. Large structural repairs involving multiple members, temporary support, and permits can take two to three weeks or longer. Timeline depends on the scope of decay, access, whether permits are required, and building inspector availability. We provide a realistic schedule in the estimate.

Do I need a permit for wood rot repair in San Francisco?

Permits are required for any structural repair involving load-bearing walls, beams, joists, sill plates, or rim joists, and for any exterior work that alters the building envelope. Non-structural trim or fascia repair may not require a permit, but we verify this with the San Francisco Department of Building Inspection. Structural repairs also commonly require a licensed structural engineer to size members and sign the design. We coordinate all permitting and inspection requirements.

What causes wood rot in San Francisco homes?

San Francisco's marine fog, salt air, and frequent moisture keep exterior wood damp year-round. Roof leaks, gutter overflow, foundation splash-back, poor drainage, condensation in crawl spaces, and failed caulking or flashing are the primary causes. Once wood stays moist for extended periods, fungal decay begins. Interior rot often starts from an undetected roof or plumbing leak. Identifying and fixing the moisture source is essential to prevent the rot from returning.

Can rotted wood be saved or must it always be replaced?

Sound wood adjacent to decay can be treated with wood preservative and saved. Wood that is soft, crumbly, or extensively colonized by fungus must be removed. Our inspection determines how much wood is truly decayed and how much can be preserved. We always propose repair and preservation where the wood justifies it, and replacement only where necessary. This keeps your cost lower and your home's original character intact where possible.

What is the best time of year for wood rot repair in San Francisco?

The marine layer and salt air keep exterior wood damp year-round, so rot here is a year-round structural problem rather than a seasonal one. Winter rains turn existing leaks into visible water damage and drive interior repair demand. Spring is when decks, porches, and stairs get opened up and rebuilt. Summer fog provides steady moisture that sustains decay. Fall and winter are busy seasons for rot repair, but we schedule work year-round. The best time to repair rot is as soon as it is discovered, before it spreads.

Do you handle emergency wood rot repairs in San Francisco?

Yes. If you discover significant rot affecting a load-bearing member, floor, or structural integrity, call us immediately at (628) 285-5429. We respond to emergency calls within 24 hours and can often schedule urgent inspections and repairs quickly. Temporary support and stabilization can be installed while a full repair plan is developed.

Is your estimate really free and no-obligation?

Yes. We provide a free, detailed inspection and written estimate with no obligation to hire us. The estimate includes a description of the decay, the proposed repair method, materials, labor, timeline, and any permits or engineering required. We explain the findings clearly so you understand the problem and your options. Call (628) 285-5429 or visit our contact page to schedule your free estimate.

Are you fully insured for wood rot repair in San Francisco?

Yes, we are fully insured and carry general liability and workers compensation coverage. We are also EPA Lead-Safe Certified, which is essential for work on homes built before 1978, covering the majority of San Francisco's residential stock. Insurance documentation is available on request. We protect your home and our crew on every job.