Wood FoundationCredit: www.naturalspacesdomes.com

Wood seems like an farfetched material to be building a house foundation with until you consider all the things a treated wood foundation would have to do to be able to answer...Yes to all those questions. Let’s go over them.

A wood foundation in Canada? Particular in Northern British Columbia...You have to be pulling my leg. Won’t it allow water to enter? Won’t it rot in a few years? Or is it even strong enough? Is it safe holding up the weight of an entire house? It must have some advantages over concrete?

 >>>> Is it going to leak? ...Even concrete foundations will crack and leak if you don’t deal with water. The water entering from below must be drained into a sump pump holding tank and then be pumped out before it reaching the ground below the footings. Water entering from above and outside is controlled by correct grading the ground away from the house. Gutters or used to take the water from the roof, or you can just install some plastic sheeting covered with rocks on the sloped ground below the eaves, or you can used both methods.

Water entering by the side walls isn’t a very big issue since gravitational force is pulling this water straight down, not forcing it sideways. All the same, a wood foundation wall is covered with a continual layer of waterproofing member atop a layer of asphalt-saturated felt.

A wood foundation is built on a layer of drain rock below the footings and the floor. This provides an uninterrupted bed to drain water away and keep the floor and ground under the floor dry. If you’re also using a wood floor, it's a good idea to spray urethane foam insulation directly on the rock base, between the floor joists, which insures that the entire floor is sealed from soil gasses and also helps keeping the floor warm and secures the entire floor in place.

Then the wood foundation walls are backfilled midway up the sides with washed rock. Any water that makes it through from the ground above is then directed to drain right down to below the footing. If you can picture it in cross section, the entire foundation and floor base is completely enwrapped in a basket of rocks.

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>>>> Won’t It Rot or get eaten by bugs? ...The type of wood used for a wood foundation is treated with salts which make it useless for hungry termites, bacteria and fungi. The salts adhere to the cellulose fiber in the wood and there's a common absorption of these salts [0.6 lbs. of salts per cu. ft. of wood] that's standard for foundation grade treated lumber used in wood foundations.

>>>> Structurally Strong...We all acknowledge that wood walls can hold up a few stories of height, but as time passes by, the ground behaves like a thick fluid, and can place a lot pressure on the wall framing. If the foundation walls are 4 feet or under in the ground, design loads can be decided from local code-approved tables. But a wood foundation that is deeper than 4 feet below grade must be engineered to resist the lateral loads that will be exerted by the weight of the backfill material.

You could believe that specifying the sizing and spacing of the studs will keep them from buckling in from the weight of the backfill, but keeping the walls in their place, at the top and the bottom, particularly during the backfill process, is a lot more significant. How the walls are attached to the basement and main floor joist structure determine how long the system can last. The lateral loads must be calculated; the sizing, type and spacing layout of the fasteners must be specified and conscientiously installed.

>>>> Is a wood foundation really safe? ...You certainly would not wish to drink the salts that are applied to the wood to preserve it. They're made with a very poisonous substance. Even the newest chemical formulas can be toxic. In the treatment process some surplus salts stay soluble and aren’t completely absorbed by the wood, and may possibly leach out of the wood if it is soaked in water. The key points to remember is wood foundations are designed not to get soaked, so there should be minimum danger of exposure to the salts used.

>>>> What are the advantages of A Wood Foundation...Wood basements generally feel warmer. Concrete foundations absorb a quite a bit of radiant heat from your body, and can make your basement cold and clammy, even if it's warm. Wood absorbs a great deal less radiant energy from you. While there’s no refusing that a concrete basement floor with in-floor heating feels great, you frequently don’t need that extra heat in a wood framed floor to feel at home. 

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Materials for making a wood foundation use up less energy. The heat required to create anhydrous Portland cement requires lots of energy, and wood does not, and is renewable.

Wood basements are simple to insulate and apply the finished wall covering without any additional structures. The electrical can be run through the studs, and then the drywall can be simply attached with no additional framing required.

Wood foundations usually cost less. The savings get better the farther out from the ground it sits. Even a foundation 6 ft. in the ground can be quite a bit less...Saving you money which you can use towards other building costs.