Log homes are actually safer than stick frame construction when it comes to house fires. People often think that log homes are more susceptible to fire damage/danger than ‘standard’ stick frame homes, because log homes are made of logs. In reality the opposite is true: a properly built log home is naturally fire resistant — and much safer than a stick frame home.
For fire safety structures are ranked within one of five different types of construction. At one end of the spectrum is Type 1, which is the most fire-resistant. Type one construction is comprised of NON-combustible material such as concrete, stone glass or steel. At the other end of the spectrum is Type 5, which is the MOST combustible. Type 5 is a ‘traditional stick frame.’
When built properly log homes can qualify as “Heavy Timber Construction,” which fits under the category of Type 4 construction. That means that log homes can perform much better in a fire than stick frame homes.
It may seem counter intuitive, but logs are actually very hard to burn. You can try this experiment (recommended by the Canadian Wood Council), obtain an unsplit round of firewood and try to light it on fire by holding a flame to the rounded side. Then try the exact same thing on a split piece of firewood. You’ll notice that if the log is in a natural state, then it is REALLY hard to light on fire – unlike kindling or a 2×4 which is pretty easy to burn.
There are a number of reasons why log homes are more fire resistant than stick frame homes.
One reason has to do with how logs have an extremely low surface area to volume ratio. Proportionally very little of the logs material can be exposed to flame at any given time – leaving the rest safely protected from the flame. The dimensional lumber that used in stick frame construction, on the other hand, has a high surface area to volume ratio — so it’s much more likely to burn at a fast rate.
Also, once wood develops a thin layer of char, the char itself acts as an insulator – which slows the burn rate pretty dramatically during a fire. This is important for a log home because logs can retain a majority of their strength even if they sustain fire damage. For instance, if a log suffers a burn that is about 1/2″ deep, the log will still retain about 90% of its original strength. This retention of strength leads to a retention of structural integrity, even when a fire has been burning for quite a while. If structural integrity is retained, that means the log home will not collapse and will be restorable – unlike most stick frame homes that go through a fire.
Often with a log home it is easy to take care of the damage if a fire does occur. For instance, we’ve seen numerous log homes that suffered fire damage and they only needed some pressure washing or light sanding and staining to look good again.
Many jurisdictions actually recognize the natural fire resistant properties of log construction.
The state of Colorado, says that in rural areas “exterior walls of buildings… [must be made of] materials approved for one-hour-rated fire-resistive construction” To meet that requirement they will accept “heavy timber (logs) construction or noncombustible material on the exterior side” of the exterior wall. So the officials of Colorado believe that natural logs are the equivalent of lumber / material that has been treated with chemical flame-retardants. For health reasons many people like to avoid using chemical flame retardant treatments, so for them a log home is the natural way to go.
And it’s not just Colorado. The BOCA (National Building Code) makes allowances for the use of Heavy Timber, or logs, in applications that specifically require the use of dimensional lumber that has been treated with fire retardant chemicals. Some jurisdictions go even further. Rhode Island, actually allows for the use of Heavy Timbers (logs) in situations that call for a true non-combustible material, they are that confident in the natural fire resistant nature of log construction. (RI Fire Laws 23-28.17-15).
Hopefully this helps dispel the myth that log homes are more susceptible to fire and fire damage than stick frame homes.
Fire safety tips:
- Use a UL listed CLASS A fire resistant roofing material, usually metal or slate/tile. According to the State of Colorado, the roof is the most vulnerable component of any structure in regards to fire danger. That’s because often a floating ember landing on the roof is where the fire starts.
- The Canadian Wood Council (which touts the natural fire resistance of natural logs) recommends that you use logs that are a minimum of 8 inches in diameter.
- Use a ‘simple’ roof design with no hips or valleys where heat can create eddies (hot spots) causing fire to penetrate the roof. When it comes to roofs and fire safety, a simple roof is the way to go.
- Use solid core exterior doors not less than 1 3/4″ inches thick.
- Use a proven fire resistant soffit design.
- In rural areas do not use wooden exterior decking material that is less than 3″ thick, and it’s recommended that one encloses the space below exterior decks so a moving forest fire cannot get beneath them.