Metal Roof Over Shingles (Retrofit) San Francisco

Metal Roof Over Shingles (Retrofit) in San Francisco

San Francisco is a city of steep hills, tight lots, and roofs that were never designed for modern materials. From the Victorian and Edwardian rows of Noe Valley and the Haight to the stucco flat-roof houses filling the Sunset and Richmond, most homes here carry one or two layers of aging asphalt shingles. A Metal Roof Over Shingles (Retrofit) in San Francisco lets you skip the tear-off, cut landfill waste, and lock in a metal roof that handles marine fog, salt air, and atmospheric-river storms without the cost of a full strip-down. We have installed metal over shingles since 2009, and we always check deck condition and local code before recommending it. If your sheathing is soft or your existing layers already hit the code limit, we tell you straight. Start with our metal roof installation overview to see where retrofit fits.

Why Retrofit Over Shingles Makes Sense on San Francisco's Older Housing Stock

Most San Francisco homes built between the 1880s and the 1950s were framed for lightweight roofing. Adding a metal retrofit system over existing shingles keeps the load close to what the structure already carries, avoids ripping open a finished attic, and shortens the time your roof is exposed to weather. It also matters on hillside homes in Bernal Heights and Twin Peaks, where scaffolding and dumpster access are expensive.

You avoid tear-off disposal fees, which run high in San Francisco because of tight street access and hauling costs.
You keep the existing shingle layer as an underlayment buffer against condensation.
You cut installation time by one to three days on a typical row house.
You reduce noise and dust inside occupied homes in the Mission and Richmond.
You can still add proper eave ventilation and new flashing at penetrations.

Retrofit is not automatic, though. San Francisco code and the California Building Code limit how many existing roof layers you can cover, and historic districts and HOA design review can restrict panel profile and color.

Key info: A 1920s Marina home with original red clay tile or a Pacific Heights parapet roof needs a different approach than a Sunset stucco flat roof. We check the existing layers and the local building department rules before we quote a retrofit.

For the official rules on re-roofing and permit thresholds, check the San Francisco Department of Building Inspection before you sign anything.

How We Install a Metal Roof Over Shingles in San Francisco, Step by Step

We do not just screw panels onto old shingles and walk away. The deck has to be sound, the shingle surface has to be flattened, and every penetration has to be re-flashed. On a fog-belt home in the Outer Richmond, we also check for rot at the eaves and around chimneys before we commit to a retrofit.

We inspect the deck from the attic and the roof surface, and we probe for soft sheathing.
We confirm the existing layer count against local code and pull the roofing permit.
We install a slip sheet or underlayment over the shingles to isolate the metal.
We fasten horizontal battens or purlins where the panel profile requires them.
We install new eave trim, valley metal, and flashing at chimneys and skylights.
We set the panels, screw them to the battens, and seal every penetration.
We clean the gutters and walk the roof with you before we close the permit.

If your home already has a metal roof that needs attention rather than replacement, we handle that through our metal roof repair service.

Key info: On a 1930s stucco row house in the Sunset, we found two layers of shingles and a dry-rotted eave board. We replaced the board, added a slip sheet, and installed a standing seam panel in two days. A tear-off would have added three days and a dumpster permit.

Retrofit Approaches We Use on San Francisco Roofs

Not every metal system works over shingles. The right choice depends on your roof pitch, the existing layer count, and whether the home sits in a historic district or under HOA review. Here is how the main options compare.

Approach	Description	Best for
Standing seam over battens	Concealed fasteners, raised seams, battens over the shingles.	Pitched roofs on Victorian and Edwardian homes in Noe Valley and the Haight.
Exposed fastener panels	Corrugated or ribbed panels screwed directly to purlins.	Budget retrofits on sheds, garages, and simple gable roofs.
Stone-coated steel	Textured panels that mimic shingle or tile.	Homes in HOA or historic review that need a traditional look.
Metal shingles	Interlocking panels that replicate slate or shake.	Spanish Revival and Mediterranean homes in the Marina and St. Francis Wood.
Low-slope retrofit	Snap-lock or mechanically seamed panels on flat and low-slope roofs.	Sunset and Richmond row houses with flat roofs behind parapets.

We match the profile to the house, not to whatever is on the truck. That matters on homes with ornate cornices and false fronts in Pacific Heights, where a panel that stands too tall breaks the original roofline.

Metal Roof Over Shingles (Retrofit) Cost in San Francisco: What to Expect

Retrofit pricing in San Francisco starts around From $7 per square foot for a basic exposed-fastener system over sound shingles. Standing seam, stone-coated steel, and metal shingle profiles run higher because of material cost and the extra labor to set battens and align seams. A typical 1,500 square foot roof in the Sunset or Bernal Heights lands in the mid five figures, and a larger Victorian with complex hips and dormers runs higher.

What moves the number: the number of existing shingle layers, deck repairs, access on steep streets, the panel profile, and whether the home falls under historic or HOA review. Getting two or three estimates is smart because contractors read deck condition differently. See our full pricing overview for a line-by-line breakdown.

Key info: A homeowner in Daly City with one layer of shingles and a simple gable paid less than a San Francisco homeowner with two layers, a flat roof, and a chimney to re-flash. Same square footage, different scope.

Metal Roof Over Shingles (Retrofit) Near Me: How to Vet a Contractor in San Francisco

San Francisco roofing contractors are not all set up for retrofit work. You want a crew that knows the local building department, understands historic district review, and will put in writing what they found under the shingles. Here is what to check before you sign.

Ask for a current license and a certificate of insurance showing general liability and workers' comp.
Get two or three written estimates that separate labor, material, deck repair, and permit fees.
Ask for references from homes with similar roof pitch and age, ideally in your neighborhood.
Confirm who pulls the permit and whether the contractor has worked in a historic district or HOA before.
Ask how they handle unexpected deck rot and what that costs per sheet.

We are a Metal Roofing Alliance member and have worked San Francisco roofs since 2009. Reach us through our contact page for a free estimate. We will tell you if a tear-off is the better call.

Metal Roof Over Shingles (Retrofit) in San Francisco: Pricing Guide

Service	Price	Details
Exposed fastener retrofit over shingles	Starting at $7/sq ft	Includes slip sheet, purlins, corrugated or ribbed panels, and standard flashing on a sound deck.
Standing seam retrofit over shingles	Starting at $11/sq ft	Includes battens, concealed-fastener panels, and new eave and valley trim; price rises with roof complexity.
Stone-coated steel or metal shingle retrofit	Starting at $13/sq ft	Includes textured panels and trim; HOA or historic review and complex hips push the number higher.
Deck repair or re-sheathing	On estimate	Priced per sheet after we probe the deck; soft sheathing or eave rot must be seen on site.
Travel	Included	In San Francisco and surrounding Bay Area cities, no separate call-out or mileage fee.
Estimate	Free	Response within 24 hours at (628) 356-4308, no obligation to book the work.

Indicative pricing, the exact cost depends on square footage, finish, and site access. Free personalized estimate within 24h at (628) 356-4308.

Metal Roof Over Shingles (Retrofit): service areas

📍 San Francisco 📍 Daly City 📍 South San Francisco 📍 Pacifica 📍 San Mateo 📍 Burlingame 📍 Redwood City 📍 Palo Alto 📍 Oakland 📍 Berkeley 📍 Alameda 📍 Richmond 📍 Walnut Creek 📍 San Rafael 📍 Mill Valley 📍 Sausalito 📍 Novato

Frequently asked questions: Metal Roof Over Shingles (Retrofit) in San Francisco

Can I put a metal roof over my existing shingles in San Francisco?

Often yes, but it depends on how many layers you already have and the condition of the deck. California code limits the number of existing roof layers you can cover, and the San Francisco building department enforces that limit at permit review. We probe the sheathing from the attic and the roof surface before we commit. If the deck is soft or you are already at the layer limit, a tear-off is the right call.

How much does a metal roof over shingles cost in San Francisco?

Retrofit pricing starts around From $7 per square foot for a basic exposed-fastener system over sound shingles. Standing seam and stone-coated steel run higher because of material and batten labor. A typical 1,500 square foot San Francisco roof lands in the mid five figures, and complex Victorian roofs with dormers and hips run more. Get two or three written estimates so you can compare scope, not just the top number.

Do you need to remove the old shingles first?

Not always. A retrofit installs a slip sheet or underlayment directly over the shingles, then battens and metal panels on top. We only recommend it when the existing shingles are flat, well adhered, and within the code layer limit. If shingles are curling, the deck is soft, or there is active leakage, we strip the roof first so we can fix what is underneath.

How long does a metal roof over shingles job take in San Francisco?

A simple gable retrofit on a 1,200 to 1,500 square foot home usually takes two to four days including permit inspection. Complex Victorians with hips, dormers, and multiple penetrations can run five to seven days. Fog and rain in the winter can add days, so we schedule around the forecast and keep the roof watertight each evening.

Do I need a permit for a metal roof over shingles in San Francisco?

Yes, most full re-roofs and retrofits require a roofing permit in San Francisco, and the threshold and inspection requirements vary by jurisdiction. Historic districts and HOA design review can also restrict panel profile and color. We pull the permit and schedule the inspection as part of the job. Always confirm the current rules with the local building department before work starts.

What is the difference between a metal roof retrofit and a full replacement?

A retrofit installs new metal over the existing shingles without tearing them off, which saves disposal cost, landfill waste, and installation time. A full replacement strips the roof to the deck, replaces any bad sheathing, and installs new underlayment before the metal. Retrofit is cheaper and faster; replacement is the better choice when the deck is compromised or the home is already at the layer limit.

What is the best time of year to install a metal roof over shingles in San Francisco?

Late spring through early fall is the most reliable window because the atmospheric-river storms of the cool, damp winter are less likely to interrupt panel setting and flashing work. Summer fog in the Sunset and Richmond can slow sealant cure, so we schedule those installs for midday. Winter installs are possible, but we plan around rain forecasts and keep the roof dried in each evening.

Do you handle emergency metal roof over shingles work in San Francisco?

Yes. If a storm has opened a roof or a retrofit panel has lifted, call (628) 356-4308 and we will get a crew out to tarp and stabilize the roof, usually the same day or next morning. We document the damage for insurance and schedule the permanent repair or retrofit once the weather clears.

Is the estimate really free and no-obligation?

Yes. We come out, inspect the deck and existing layers, check the permit requirements, and give you a written estimate at no cost. You are not obligated to book. We would rather you compare two or three bids and pick the right contractor than feel pressured into a decision on the spot.

Are you licensed and insured for metal roof over shingles work in San Francisco?

Yes. We carry general liability and workers' compensation coverage and can provide a certificate of insurance on request. We are a Metal Roofing Alliance member and have worked San Francisco roofs since 2009. Ask any contractor you interview for the same documents before work begins.