Asbestos Siding on Older California Homes

Asbestos-cement siding was widely used on American homes from roughly the 1920s into the 1970s. It was cheap, fire-resistant, and durable — which is why a lot of it is still on houses across Sacramento, the Bay Area, and older Northern California neighbourhoods today. If you are planning to re-side a home from that era, this is something to settle before the project is scoped, not after the first shingle comes off.

What it looks like

Common characteristics of asbestos-cement siding include:

• Small rigid shingles or panels, frequently around 12 by 24 inches rather than long boards.
• A hard, brittle, cement-like feel — it cracks rather than flexes, and it will not dent.
• A wavy, scalloped, or notched bottom edge on many shingle patterns.
• Pre-drilled nail holes, because the material cannot be nailed through without splitting.
• A faintly textured surface, sometimes imitating wood grain.
• A home built before roughly 1980.

None of this is confirmation. Modern fiber cement siding — the category James Hardie and others make today — is asbestos-free and can look broadly similar to an untrained eye. Age and appearance raise the question; only a laboratory answers it. For what current fiber cement actually is, see our cement board siding guide.

What not to do

The hazard is airborne fibre, and intact material bound in cement does not readily produce it. These actions do:

• Do not pressure-wash it. This is the most common accidental disturbance, because it feels like ordinary maintenance.
• Do not sand, grind, or sand-blast it, including as paint preparation.
• Do not cut or drill it — for a new light fixture, vent, satellite bracket, or hose bib.
• Do not break it up for easier disposal, and do not put it in household waste.
• Do not let a contractor tear into it because they are confident it is "probably fine." Confidence is not a test result.

Damaged shingles that are already cracked or crumbling deserve more caution, not less. Leave them alone and get advice.

Testing

Confirmation means laboratory analysis of a physical sample. Because taking the sample disturbs the material, it should be collected by someone qualified to do it safely — a certified asbestos consultant or an accredited testing firm — rather than by snapping off a corner yourself.

Test early. On a pre-1980 home the result changes the scope, the sequence, the budget, and the timeline of a re-siding project, and all of those are much easier to absorb during planning than during demolition.

If the result is positive

Asbestos abatement is a separate, separately licensed scope of work. It is not something a siding contractor folds into a re-side. In practice a project then runs in this order:

1. Assessment by a certified consultant — what is present, in what condition, and how much.
2. Notification where required. Your regional or local air quality management district sets these obligations and they vary by district and by the size of the job.
3. Abatement by a licensed abatement contractor, under controlled conditions with regulated disposal.
4. Clearance, then the wall is available.
5. Re-siding begins — and with the wall newly exposed, this is the moment to inspect the sheathing and install a proper weather-resistive barrier before new cladding goes on.

Heritage Exteriors does not perform asbestos abatement — that requires separate licensing and certification. What we do is re-side the home once the wall has been cleared, and scope the project honestly around that sequence rather than discovering it halfway through.

Who regulates it in California

More than one authority, depending on the aspect:

Requirements differ between districts and change over time, which is why this page names the regulators rather than quoting thresholds. Confirm what applies to your address with your local air district and a certified consultant before work is scheduled.

The practical takeaway

If your home predates about 1980 and has brittle cement shingles, assume the question is live and get it tested during planning. It is a modest cost that removes the worst version of this problem — finding out mid-demolition, with a crew on site, an open wall, and a schedule that no longer works.

For what a re-side involves once the wall is clear, see our siding replacement cost guide and James Hardie siding.

Working with Heritage Exteriors

Heritage Exteriors (CSLB #1055919) re-sides homes across Sacramento, the Bay Area, and Lake Tahoe, including plenty of houses old enough for this to be a live question. We will tell you when testing should happen before we quote. Get in touch or call (916) 546-2991.

Reviewed August 2026. General information only, not a substitute for assessment by a certified asbestos consultant. Regulatory requirements vary by air district and change over time — confirm current obligations with your local authority.