Better Natural houses have 3 unique building materials that are each fireproof, making the house as a whole almost fully fireproof.
- Clay brick walls
- Foamed concrete insulation
- fire resistant roof tiles and MgO roof substrate. (optional)
1. Clay brick walls.
Our walls have a lumber frame, covered with 2.5″ thick bricks from solid clay, pressed under 40 tons of pressure. These clay bricks don’t burn…ever. The wood inside the frame is never exposed so a fire won’t ever reach this.
2. Foamed concrete insulation
Our exterior walls have 6 to 8″ of foamed concrete insulation, completely shielding the interior wood structure, while the roof structure typically has 12 to 16″ of foamed concrete. Foamed concrete is known to be fireproof, even more so than regular concrete, because of it’s much lower thermal conductivity and expansion coefficient.
3. Fire resistant roof tiles and MgO roof substrate. (optional)
Even if the roof would catch fire, the house is largely protected by the thick insulation layer of foamed concrete. Still there are two additional layers of protection we can add to protect the roofs.
Using Fire resistant roof tiles (from concrete or fired clay) instead of asphalt shingles will help, though this will significantly increase the cost of the house, and there’s always a possibility that embers can fly in between the tiles and set the substrate on fire.
A safer and more cost efficient way to protect the roof is replacing the standard OSB or plywood roof substrate boards with Magnesium Oxide (MgO) cement boards. MgO boards have been the building material of choice in Asia for more than 50 years (largely because of the large MgO deposits there) and imported boards are becoming more popular in the US as well. They combine all the best properties of wood and cement boards. They are much stronger than traditional cement boards, about as strong as wood, but unlike wood, they are fully fireproof, fully insect proof and waterproof, which means your roof won’t have to be replaced in 30 years due to wood decay. Replacing a wood substrate with an MgO substrate increases the cost of the roof by about $5 per sq ft.