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What Is an Open Foundation?

June 13, 2014

Have you ever received your WSRB inspection and noticed a phrase indicating the building had an “open foundation”? While not uncommon, open foundations are openings that go beneath the building, generally into a crawl space or other open space beneath the floor joists. Other than those under docks, wharves, and piers, open foundations are generally an avoidable condition and closing, or protecting, them can help improve the overall fire safety of a building.

Open foundations can appear in a number of ways:

  • A masonry wall resting on a combustible foundation that rises above the low water markopen foundation 2
  • A trailer-type structure on stilts without protection running along the bottom of the building, between the floor of the structure and the groundtrailer
  • A building with an unprotected opening into a basementopen foundation

Open foundations are a concern for the simple reason that anyone walking by could accidentally discard a cigarette or other burning material underneath the building. A smoldering fire in a crawl space could easily go unnoticed and quickly grow into a large fire, possibly working its way up the wall joists and across the underside of the floor. They also create a potential for arson or other dangerous activity, as any burning items could purposely be thrown into the crawl space.

Open foundations are also an attractive nuisance. They look like an easy place to throw garbage or other trash which can then pile up underneath the building and, over time, could attract more and more refuse. Accumulating trash and other debris can serve as fuel for a potential fire or cause the building to be a further target for vandals.

To protect a building, do a quick walk around the outside of the structure. Take notice of any holes or chutes into a crawl space or below-floor space and ensure that chicken wire or other protection is properly covering the opening and secured on all sides. If a trailer is being held up by combustible posts or foundations, attach chicken wire or trellis along the outside perimeter to help enclose the area and make it difficult for burning materials to be discarded underneath.

Keep in mind that open space beneath a second story is not considered the same as an open foundation. In the pictures below, the second stories extend out over the parking lots and would be considered as open sides 2open sides

Article by: Kristen Skinner

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