Most – but not all – bungalows were built with sufficient ground clearance.
Some bungalows have less ground clearance than is permitted under the current Building Code. These are most likely to be found on sloping ground.
A lack of ground clearance may not be a problem as long as the soil under the house is dry and there is sufficient ventilation.
Minimum ground levels can be addressed by:
- sloping the site around the perimeter away from the building so that water does not drain underneath it
- raising the house to increase the clearance if repiling
- installing a concrete floor slab over a damp-proof membrane.
Trenching may be necessary to achieve access to the underfloor space (Figure 1).
If an extension is proposed in which the existing floor level is lower than permitted under the Building Code, but there is no evidence of damage from subfloor moisture, apply to build to the existing floor level as an Alternative Solution and specify timber with a higher level of treatment or natural durability.
Cover the ground with polythene to reduce moisture evaporation into the subfloor space.