You may have heard or read that some neighbourhoods in Hawaii have just been destroyed in wildfires, and at the time of writing, 53 people are reported to have died in Maui as a result. Unless your house is parked in the middle of YVR airport, your neighbourhood is equally vulnerable; I'll explain why your home is similarly at risk and recap the three main things you can do to protect your home.
Wildfire Fueled By A Hurricane
Your house doesn't need to be located next to a forest or clearly be situated in the Wildland-Urban Interface. A forest fire can travel through a forest across the tree canopy, but it makes the greatest distance when winds carry the embers. The result can be an ember shower blasting everything downwind and torching anything it finds. Embers typically can be carried two kilometres in ordinary windy conditions, but when the winds are higher as they were in Lytton due to the extraordinarily high temperatures the fire can travel farther, faster.
The winds just outside the damage zone of Hurricane Dora were still as high as 100 km/h and pulled the embers from existing wildfires across the island. This NBC News article (link) explains how those winds combine with a mountainous terrain to amplify the ferocity of the wildfires. Despite being a seaside community in a lush tropical environment, Lahaina was burned down all the way to the shoreline.
The Okanagan and the Thompson-Nicola regions are both arid, mountainous environments which have been experiencing more frequent wildfires. In contrast, Vancouver Island, the Sunshine Coast, the North Shore, and the Fraser Valley of BC include metropolitan centres surrounded or flanked by heavily-vegetated, mountainous terrain. The province and coastal municipalities have inter-agency plans in place to respond aggressively to a wildfire breaching an urban community here, but if sustained high winds combined with dry conditions (such as another heat dome) occur when a forest fire flares up nearby, the speed at which the wildfire travels could get past the firefighting defense. Are you sure that your neighbourhood won't end up razed like Santa Rosa (Tubbs fire 2017), Paradise (Camp Fire 2018), or Lahaina (West Maui fires 2023)?
Five Problems, Five Solutions
The threat of a wildfire eating away at your house boils down to basically four vectors.
1. Wind
The first problem is high winds.
Solution: We can't do anything about the wind, so ensure that the construction of your home - most importantly the attachment of your roof material and siding - will hold up securely to strong, gusty winds.
2. Roofs
The second threat to your house in a wind-driven wildfire is embers landing on your roof and building a nest in the valleys and eaves where they become significant fires that generate enough heat to burn down into your house.
Solution: If you're designing a new house, ensure that the form is simple and doesn't include extra peaks solely for aesthetic reasons. A simple shed or gable roof will help a lot. The second part of the solution is to pick a noncombustible, ignition-proof finish such as standing seam metal or concrete tiles.
3. Wall Siding
When a fire crawls up to your house, the heat or the flames themselves can ignite wood siding, foam-backed stucco, or melt vinyl siding (and then ignite the wood sheathing behind).
Solution: You can choose a noncombustible finish for either a new house or a renovation. Examples of suitable materials are brick, fibre-cement panels (e.g. Hardie, öko Skin, Ceraclad), cementitious stucco, and metal siding.
4. Openings
Problem: A house built of concrete (or ICF) can still be burned out by fire that enters through the doors, through attic vents, into crawl spaces, or - more commonly - through windows. Heat from a nearby fire will cause windows to shatter from thermal stress.
Solution: Double-glazed windows aren't as bad as single-glazed, and triple-glazed windows are better, but using noncombustible swing-style shutters, overhead fire shutters, or rolling fire screens (e.g. CrimSafe) will most likely prevent fire from getting in through the windows.
If you're building a new house, don't use a crawl space. Just don't. I'll write a future article about that. If you already have a crawlspace, block off all around the perimeter.
Attic vents are a necessity for attics, so any vents must have 3mm (1/8") metal screens behind them to prevent embers from being drawn into the attic. If you're building a new house, please design a vaulted ceiling with continuous exterior insulation; it will perform much better in several ways.
Your front door should be a fire-rated metal door with no window in it. Use instead a sidelite with a protective shutter or rolling grille.
5. Nearby Fire Load
Many of the fires that consumed houses during the Lytton fire were started by embers that landed in piles of random debris or stored goods sitting next to the house. In other fires, trees and bushes adjacent to the house act like torches held right up against the siding and naturally set the house ablaze. In Metro Vancouver, Stage 2 watering restrictions just went into effect last week in response to unusually high water consumption this year. Increasingly dry vegetation contributed to the extent of the Canadian wildfires of 2023.
Solution: Use paver stones or a 6" deep clean gravel bed for 5' (1.5m) all the way around your house; make this wider where your roof overhang is deeper. Use drought-resistant ground cover plants that - unlike grass - do not require regular watering or any maintenance. This combination will help keep the fire set back from the face of your house.
Trust the Expert
I've completed the technical design for numerous buildings of varying types and strict requirements for resistance to fire. In addition to understanding the specific requirements laid out in the British Columbia Building Code and researching appropriate products that satisfy those limitations, I have followed research into new materials and combinations of building products.
If you live in a typical house, expect typical results when a wildfire passes by.
If you want to upgrade your house or improve the design of your new house to the same level that is demanded of high-importance high-risk buildings such as apartment buildings or schools, you can book a free 30-minute Diagnostic Session to discuss.
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