Some bungalows will need to be repiled or levelled.
The original timber piles in bungalows will generally have been replaced by precast concrete piles or treated timber piles. If piles have been replaced, the remains of the original timber piles are generally still in evidence (Figure 1).
Where precast concrete piles have replaced original timber piles, they are likely to have been replaced as ‘like for like’ – that is, with ordinary piles only. This means there may be no lateral bracing in the foundation, so this should be checked (see Inadequate foundation bracing below).
More recent repiling is likely to have used H5-treated square radiata pine replacement piles, and is more likely to include some lateral bracing – but this should be confirmed.
Wire ties connecting piles to bearers should be checked for corrosion, and where there is evidence of corrosion the ties must be replaced.
Where in situ concrete piles are original, there may be no connection between piles and bearers. In that case, ties must be installed.
Also see uneven floors for advice about other possible problems with piles.
Timber piles that have rotted must be replaced either with H5-treated timber piles or precast concrete piles. They can be installed:
- from underneath the floor if there is sufficient working space (minimum 450 mm clear)
- from above the floor by cutting holes through the floor (approximately 450 mm square) or removing floorboards.
When repiling into soft ground, it may be necessary to install deeper piles in order to reach solid bearing ground. This can be done with small diameter steel pipe piles that are coated to resist corrosion. They are driven or augured down to the required level and then a concrete pile is cast around the top.
In extreme cases where the house is built on deep unsuitable ground, it may be necessary to remove the roof so that long piles (such as railway line) can be driven down to firmer ground.
If the floor is out of level, employ a firm experienced in repiling and levelling work to jack the settled parts of the building back to as near level as possible. Piles and/or damaged subfloor framing must also be replaced to maintain the building in the level position.
This process may result in damage to wall linings and doors and windows, in which case remedial work may be required after levelling. Consider this before you decide to relevel.
If additions or alterations were made to the building after the floor settled, an assessment should be made of the effect of levelling the building on the additions and alterations including fittings and services that were added after the floor settled.
If levelling is not practical, the floor may be:
- left as it is, if acceptable to the owner
- overlaid by a new timber, plywood or particleboard floor, packed to make it level
Where there is a ‘hump’ in part of the room due to settlement around, for example a fireplace, it may be able to be levelled by removing some of the piles and allowing the floor in that area to settle – sometimes weighting is necessary to force the floor down.