I’ve been building in the East Bay hills since the early 2000s — long before the term “Wildland-Urban Interface” became standard construction language. The fire risk in Lamorinda, the Oakland Hills, and the Diablo foothills has always been real. What’s changed isn’t the risk. It’s what we now know about how homes actually survive a wildfire — and what kills them.
The answer, in most cases, isn’t the fire itself. It’s the water.
What the Palisades Fire Taught Us
When neighborhoods burn simultaneously, the municipal water system is overwhelmed. Hydrant pressure drops. In severe cases, pressure disappears entirely. The homeowners who saved their properties in the Palisades fire and other recent California events weren’t relying on the fire department or the municipal supply. They were fighting with pool water, garden hoses, and whatever independent water supply they had on site.
This is the scenario I think about when I’m designing a fire-resilient home. Not a single fire burning toward an otherwise intact grid — but a simultaneous neighborhood event where the systems most homeowners count on have already failed.
The Building Envelope Comes First
Before any discussion of water supply, I want to be clear about something: fire suppression is the last line of defense, not the first. A home that ignites easily doesn’t give the suppression system time to work.
At Scott O’Hara Construction, fire resilience starts with the building envelope — and the goal is a home that is as close to vent-free as possible.
What I mean by that is a continuous sealed assembly from crawlspace to roof deck, with no unprotected openings for embers to enter. At 35 Donald Drive in Orinda, that meant:
- Sealed and conditioned crawlspace — vapor barrier, rat slab poured throughout, all existing foundation vents removed and sealed. No open pathways for embers to enter the subfloor cavity.
- Sealed attic assembly — 2 inches of closed-cell rigid foam installed above the roof deck, creating a continuous thermal and air barrier. No ridge vent. No attic venting of any kind. Embers have no way in.
- Standing seam metal roof with ember-resistant eave and gutter details
- Custom redwood siding over 5⁄₈” Dense Glass non-combustible sheathing — 1-hour rated wall assembly
- Closed eaves — no gaps for embers to collect and ignite
- Interior and eave fire sprinklers
A note on spray foam: The sealed attic assembly at Donald Drive uses rigid foam board above the roof deck — not spray foam applied to the underside of the roof sheathing. Spray foam is widely used and can be effective, but I don’t use it as my primary air sealing strategy in sealed attic assemblies. Rigid foam above the deck, combined with meticulous air sealing at every penetration and joint, achieves the same result without the concerns around spray foam’s long-term performance, fire rating requirements, and the difficulty of future repairs or modifications. A sealed home doesn’t require spray foam — it requires attention to detail at every layer of the assembly.
The result at Donald Drive is a home with no unprotected openings. Every potential ember entry point has been eliminated or protected. This is what WUI construction looks like when it’s done completely — not a checklist of materials, but an integrated assembly designed to deny fire access to the structure.
I’ve been building to these principles in WUI areas since the early 2000s, before the regulatory frameworks caught up with what the fire science was already telling us. The Moraga-Orinda Fire District, which governs much of my primary market, is one of the strictest fire jurisdictions in the state — and even their requirements represent a floor, not a ceiling.
Much of what I know about wildfire behavior and building vulnerability I’ve learned directly from the researchers who study it. I’ve attended presentations by Dr. Joseph Lstiburek of Building Science Corporation — widely considered the dean of North American building science — and by Dr. Stephen Quarles, former Chief Scientist for Wildfire and Durability at the Insurance Institute for Business and Home Safety (IBHS), whose decades of research on ember intrusion and WUI construction have shaped how I think about every vulnerable detail on a project. When the researchers who study how homes fail in wildfires tell you what matters, you pay attention.
The Water Problem: Two Solutions
Once the envelope is hardened, the question becomes: what happens when the fire gets close enough that active suppression is needed, and the municipal water supply is gone?
I’ve developed two systems depending on the site conditions.
Solution 1: Pool-Fed Fire Suppression
At 35 Donald Drive, the answer was straightforward — there was a pool on site with 15,000 gallons of water. The question was how to use it.
We installed a dedicated pipe from the bottom of the pool near the existing pool equipment, connected to an LSF-300A NFPA-13D residential fire pump — a 3-horsepower, 240-volt stainless steel unit capable of delivering 54 GPM at 49 PSI. The house fire sprinkler system, including eave sprinklers, requires 26.4 GPM at 48 PSI. The pump is also sized to handle exterior yard perimeter sprinklers simultaneously.
The system connects to the home’s fire water line after the backflow preventer — preventing pool water from contaminating the house supply — and runs off the battery system with generator backup. When PG&E goes down and municipal pressure fails, which is exactly when you need it most, this system is fully operational.
With 15,000 gallons available and 300 gallons required per 10 minutes of run time, that’s roughly 8 hours of independent firefighting capacity.
The pump and controls are managed through a Pentair IntelliCTR panel with cellular capability, and the system integrates with the homeowner’s insurance provider, which offers active home protection assistance.
At the 2026 Forum on Measured Home Performance — where I presented alongside Brett Singer and Woodie Delp of Lawrence Berkeley National Laboratory — the Donald Drive fire suppression system drew significant interest from attendees. But the question I heard most often was: what about homes without a pool?
Solution 2: Dual-Purpose Underground Storage Tanks
Most homes in the East Bay hills don’t have pools. They need a different answer — and that answer turns out to solve two problems at once.
New construction in California is subject to C3 stormwater retention requirements. Any project adding more than 2,000 square feet of impervious surface — roofs, driveways, patios — must manage the runoff from a 1-inch storm event. For a 2,000 square foot impervious footprint, that’s approximately 1,300 gallons of “live storage” that must be retained on site and released slowly over 48 to 72 hours to reduce peak storm drain flow.
Most contractors solve this with a simple detention tank that fills during storms and drains. That works for the permit. But it leaves thousands of gallons of underground capacity doing nothing for the other ten months of the year.
My approach uses a two-tank system:
Lower tank — collects roof and driveway runoff during the rainy season, satisfying the C3 live storage requirement. A valve allows the live storage portion to drain within the required 48-72 hour window after a storm event. In the dry season — when fire risk is highest — this tank retains water available for yard and perimeter suppression.
Upper tank — filled with city water and dedicated to the house fire sprinkler system as a backup supply. This tank remains full year-round, independent of rainfall.
Both tanks are connected to the same fire pump system, providing layered redundancy: city water first, upper tank backup, lower tank for exterior suppression.
The tanks are installed underground during site work — a natural part of the grading and drainage scope on any new construction or major renovation project. The incremental cost to add fire suppression capability to a required stormwater system is significantly lower than installing a dedicated fire water system from scratch.
When I presented this dual-use concept at the 2026 Forum on Measured Home Performance alongside Brett Singer and Woodie Delp from Lawrence Berkeley National Laboratory, it generated more discussion than anything else I showed. The audience immediately recognized what makes it compelling: it turns a regulatory requirement into a life-safety asset. Every home that needs C3 compliance is a candidate for this system.
The Complete Picture
A fire-resilient home isn’t one thing. It’s a layered system where each element supports the others:
The sealed envelope slows ignition and buys time. The metal roof and non-combustible cladding resist direct flame and ember contact. The interior sprinklers protect the structure if fire does breach the envelope. The independent water supply keeps the sprinklers running when the municipal system fails. The battery and generator backup keeps the pump running when the grid goes down.
Remove any layer and the system is weaker. Build all of them together and you have a home that can defend itself.
I presented this integrated approach at the 2026 Forum on Measured Home Performance not because it’s theoretical — but because I’ve built it. At 35 Donald Drive, every element is installed and operational. The homeowners have 15,000 gallons of independent water supply, a pump that can run for 8 hours on battery alone, a sealed envelope with no ember pathways, and a metal roof that has already survived multiple fire seasons.
That’s what fire resilience actually looks like. Not a single upgrade. Not a checkbox. A complete system designed for the scenario where everything else has already failed.
Planning a Major Project? Let’s Talk About Fire Resilience.
If you have a significant renovation, addition, or custom build planned in Lafayette, Orinda, Moraga, Danville, Alamo, or anywhere in the East Bay hills, a fire resilience assessment should be part of the early conversation — not an afterthought. The best time to integrate these systems is during the design phase, when walls are open and site work is already planned.
Scott O’Hara Construction offers a free project assessment for homeowners considering large-scale renovation or new construction in WUI areas. We’ll evaluate your site, your current envelope, and your options for independent fire suppression — and give you a clear picture of what a truly resilient home looks like for your specific property.
Book Your Free Project Assessment
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Scott O’Hara Construction specializes in large luxury home renovations, custom homes, and high-performance construction in the East Bay — serving Lafayette, Orinda, Moraga, Danville, Alamo, Walnut Creek, Pleasant Hill, and the surrounding hills.