Drywall Repair & Patching in San Francisco

Plaster or drywall: in San Francisco they are two different trades

Asking costs nothing. Describe the wall and the job goes to local independent pros who do that work - up to three of them - and they quote it. The Handyman SF does not do the work and never charges you.

The first question about a hole in a San Francisco wall is not how big it is. It is what the wall is made of, because the state licenses plaster and drywall as separate trades and much of this city is still plaster.

What a wall repair usually covers - and what it does not

Two licence classes, two different walls

The Contractors State License Board defines C-9 as drywall: "A drywall contractor lays out and installs gypsum wall board and gypsum wall board assemblies including nonstructural metal framing members, and performs the taping and texturing operations."

Plaster is C-35, a separate class: "A lathing and plastering contractor coats surfaces with a mixture of sand, gypsum plaster, quick-lime or hydrated lime and water, or sand and cement and water." Patching original lath-and-plaster is that trade's work, not a drywall contractor's.

Why old plaster fails where you hit it

Plaster on wood lath holds on by its keys - the plaster that squeezed through the gaps between the lath strips and hardened on the far side. They share the load between them, so when a few break the neighbouring keys take more, and the damage spreads instead of staying where it started.

That is also why so many old San Francisco flats have a picture rail near the ceiling: hanging from a rail and a hook is how you put art on a plaster wall without driving nails into it.

Questions people actually ask first

What does it cost to ask?

Nothing. There is no charge for the request or the introduction; the pro quotes the patch when they see it.

How quickly will someone get back to me?

A request that arrives during the day goes out to local pros the same day; one that comes in overnight goes out the next morning.

My wall is old plaster, not drywall. Is that the same trade?

No. The state licenses them separately - C-9 is drywall, C-35 is lathing and plastering. Patching original plaster properly is C-35 work, and it is a fair question to ask before someone starts.

The crack above my door keeps coming back. Why?

A crack that reopens in the same place is usually reporting movement rather than a bad patch. USGS mapping puts the city's most vulnerable ground on the fill laid over former bay floor, and buildings on it settle and shift. Worth diagnosing before filling it a second time.

Can I hang a heavy mirror on a plaster wall?

Carefully, and ideally not with a nail. Plaster holds on by keys behind the lath, and breaking a few makes the neighbours carry more. That is exactly why those flats have a picture rail.

What to ask before the patch

• Is this wall lath-and-plaster or drywall - and if it is plaster, does the contractor hold C-35 rather than only C-9?
• If the building predates 1978, are lead-safe practices being used when cutting into or sanding old paint?
• Has the texture coat or joint tape been checked for asbestos before anyone sands it?
• Is this a shared or party wall, or part of a fire-rated assembly? That can change whether a permit is needed.
• If this crack has reopened before, what will be done to find out why, rather than patching it a second time?

Where these facts come from: CSLB C-9 classification, CSLB C-35 classification, BAAQMD asbestos programme, EPA Renovation, Repair and Painting, USGS, Bay Area liquefaction maps, SF soft-story retrofit programme.