A sub-floor is the foundation, the rest of the property is built on. On wood-frame floors, the subflooring provides a continuous structural surface over the floor joists. In basements and in homes with slab-on-grade foundations, the subfloor may simply be a concrete slab.

There’s a wealth of information down there. For Building and or Pest Inspectors, the subfloor is often where we discover the true state of a home. An inspection of the sub-floor can reveal any moisture related problems such as leaking wet areas (bathrooms, kitchens, laundries), site drainage issues, lack of adequate structural support or subsiding piers/footings as well as evidence of termite entry, wood rot and mortar decay. Bathrooms, kitchens and laundries that look fine within the house can reveal a totally different story in the subfloor area.

A well-maintained sub-floor space will generally have less defects and their nature will most likely be minor. Finding these minor problems before they escalate will minimise headaches and expense.

Performing routine inspections is one thing you can do help in maintaining your property and deal with any issues proactively.

Subfloor - water damaged flooring from gradual bathroom leak.

Subfloor - rust/corrosion to steal foundation piers.