1. Fire Intrusion:
There are points where wind carried embers that can travel miles and easily make entry into a house.
a. Houses with raised floors/crawl space and/or an attic, are required by the Building Code to be ventilated. Vents can allow embers to enter the attic or crawl space. Debris in the crawl space and exposed framing in both spaces can ignite. Embers can also be deposited into planting areas below exposed wood rafter tails. Fire sprinklers in these spaces can protect these spaces.
b. The need for such ventilation can be eliminated through design.
c. Ventilation openings are required to be screened with hardware cloth with a minimum of 1/16” and a maximum of 1/8” opening.
d. The rafter spaces where the vents are located can be drywalled, providing protection for the framing. Perhaps a series of screened baffles like a sound baffle built out of non-combustible material with mineral wool to capture the embers could allow the air and trap embers.
2. Exterior Materials:
It should go without saying that hard non-flammable materials on exterior walls and roofs are a good way to prevent exterior ignition.
They are now mandatory per Chapter 7A of the California Building Code, Materials and Construction Methods For Exterior Wildfire Exposure.
a. Stucco/Exterior Plaster is a good defensive material. Stucco screeds can be used to divide the finished surface into segments resembling panels, or a grid.
b. If you must have siding, consider fiber-cement siding. It comes in various size planks and is available smooth or textured and can be pre-primed and even pre-finished.
c. Fiber cement can also be used to ‘box’ the eaves, it is also termite proof.
d. Fiber cement also comes in panels and can be field cut to the desired size and are a good fit for a contemporary house.
e. Metal siding is another option and comes in panels and planks.
3. Non-Combustible Roofs:
There are many examples of non-combustible roofs.
a. Metal standing seam
b. Slate
c. Clay tile & Lightweight concrete tile
d. Fiber cement boards
e. Living roof can save a roof from catching fire. The planting may burn away but the soil will protect the roof underneath from burning. Living roofs also provide additional sound and heat/cooling insulation.
Roofs are all designed with a shingling method to make water pass, on its’ downward path, off the roof. With any roof care, will need to be taken to prevent wind driven embers from being pushed up into spaces between tiles or shingles allowing the embers to burn the under lament.
4. Tempered and Fire Rated Glazing:
Using tempered glass helps to reduce the risk presented by regular glass breaking because of the heat and fire entering the building through a broken window. Standard window glass will shatter at about 250 degrees Fahrenheit, and tempered glass can last to about 500 degrees.
a. Fire Protective and Fire Resistive glass. ‘Fire Glass’ is also available. Fire glass is clear just like window glass. I’m not talking wire glass… We often use Fire Protective and Fire Resistive Glass in multi-family and mixed-use projects where a fire separation is required but the ability to see through the wall or door is desired.
b. Fire-rated glass, can typically survive heat over 1600 degrees F.
c. Glass ceramics are a relatively recent development in the fire-rated glass industry. This type of glass shares many properties with glass and ceramic due to the controlled crystallization process that toughens it. In addition to withstanding heat and thermal shock, it can come in a variety of arrangements, can be laminated or filmed to achieve higher impact safety ratings and pass the required hose stream test for fire separation uses. It can also achieve a fire-rating up to 3 hours. Glass ceramics do not have a wire mesh and can be used in a wide variety of applications due to their ability to offer substantial fire protection. This requires special framing that is typically large and appears institutional.
d. There are advancements in Fire rated ceramic glass being made, with panel sizes up to 51”x99”.
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