Preserved Wood Foundations (PWF) consist of below grade load-bearing stud walls made from preservative-treated plywood and typically sheathed with preservative-treated plywood lumber. They are sometimes referred to as permanent wood foundations as well.
PWF have been around since the 1960’s and are used in constructing both residential & commercial use buildings. Its advantages include:
- design flexibility & versatility
- ease of installation
- cost savings (in many cases)
- longer lifespan
- ease of interior finishing, insulating, decorating & remodeling.
PWF need to be designed by professionals and constructed by qualified builders who understand the importance of base preparation, the use of correct corrosion resistant fasteners, drainage, back filling & sealing requirements. Designed or installed incorrectly it can, for example, let water / moisture into the home which eventually will compromise the structural integrity of the foundation and increase the potential for mould. In addition, there are structural concerns with these foundations due to the soil pressure / force on them.
As most of the PWF’s are not visible during an inspection, any evidence of dampness / moisture or concerns with its structure will result in the inspector referring you on to other experts. Also, speak with your insurance company to ensure coverage is available and premiums are acceptable to you.
If you’re considering buying a home with a PWF do you homework!