Permanent Wood Foundation

Prompt

Can we build below grade without concrete?

Findings

Permanent wood foundations are wood-based foundation walls that rely on good detailing and wood preservatives to ensure a robust foundation. While this runs counter to many assumptions about foundations, it is actually a time-tested approach that has been included in the International Residential Code and can offer both performance and carbon footprint benefits. We use several layers of protection outside the wood: drain board as a capillary break and slip sheet, rigid insulation, and fully-adhered waterproofing. When these layers are detailed and installed well, we consider a wood foundation wall actually preferable to concrete: it behaves the same as the framing above, preventing cracking and differential movement.