Chimney Cap Installation for Palo Alto Homes

Chimney cap installation in brief

We measure the flue and the top of the chimney, then check the crown or chase top the cap will sit on. Next we choose a cap that fits the opening and has the right mesh, and fasten it securely. The cap should still come off when the flue needs sweeping. On masonry chimneys the cap usually mounts to the flue tile or the crown. On factory-built chimneys it has to suit that system. Our chimney cap installation service covers cap styles and materials in more detail.

Palo Alto rules that affect what goes on top of a chimney

Three City of Palo Alto sources speak directly to the top of a chimney. Here is what each one says, who it applies to and how it changes the job.

Roof work and existing chimneys

Palo Alto Ordinance 5566 (2022 California Residential Code local amendments) requires a spark arrester to be installed on an existing chimney whenever any repair, replacement or alteration is made to the roof. (Source: City of Palo Alto - Ordinance No. 5566, Chapter 16.06 California Residential Code 2022 local amendments.)

This applies to any homeowner with an existing chimney who is repairing, replacing or altering the roof. For those homes, ember screening on the chimney is part of the roof project, not an optional extra. If a reroof is coming up, plan the cap at the same time. We can fit a cap with spark arrestor mesh so the chimney top is dealt with while the roof work is underway.

Screen sizing and access for cleaning

At final inspection of a fireplace chimney transition frame, Palo Alto's inspection guideline requires a listed spark arrestor sized at four times the flue's net free area, accessible and removable for cleaning. (Source: City of Palo Alto Development Services - Inspection Guidelines: Fireplace Chimney Transition Frame.)

That requirement is written for transition-frame work specifically. If your chimney is part of that kind of project, the arrestor has to be a listed unit, its screen area must be sized to the flue, and it must come off for sweeping. That is why we measure the flue before choosing a cap and fit it so it can be removed rather than permanently fixed in place.

Decorative shrouds on factory-built chimneys

Palo Alto's roofing inspection guideline states that architectural chimney shrouds are not allowed unless they are listed as part of the fireplace. (Source: City of Palo Alto Development Services - Inspection Guidelines: Roofing (New and Reroofs).)

This mostly affects homes with a prefab fireplace and a chase on the roof, where a decorative shroud is often wanted for looks. For these homes, a shroud has to be one listed as part of that fireplace, not a generic decorative piece. We check the fireplace's listing before ordering anything for the top of a factory-built system.

When a new cap is the right job, and when it isn't

• A new cap fits when the flue is uncapped, when roof work triggers the spark arrester rule, or when a factory-built chimney needs a cap that suits its system.
• If the existing cap is rusted, bent or loose, we replace it rather than adding a second one.
• If birds or animals are already inside the flue, they and any nest come out before a cap goes on. Otherwise the cap just traps them.
• If the crown is cracked or the flue tile is broken at the top, that gets repaired first so the cap has something solid to fasten to.
• If you don't know the chimney's condition, start with chimney inspection for homes in Palo Alto and decide on the cap afterward.

Still weighing whether a cap is worth it on your chimney? Read our guide to do you need a chimney cap for the trade-offs.

More for homeowners in Palo Alto

For cap types, materials and what the job involves on any chimney, read how chimney cap installation works. For the rest of our work in the city, start at our Palo Alto area page.