Checking and repairing flooring

Older buildings were constructed with timber boarded floors that were laid within each room after the building was closed in.

Good quality matai was the most usual timber – if in good condition, it can be sanded and varnished to give an attractive finish. 

Old matai flooring should be checked for borer and rot, and any damaged boards cut out and replaced with new timber.

Rust can also chemically attack timber around an affected fastener – something known as ‘nail sickness’ (Figure 1). The dark staining around nails in old floorboards may be unsightly and indicate a slightly weakened part of the timber, but is not generally a structural risk.

Figure 1: Nail sickness

Original floor boards are often split, particularly along the tongue and groove  joint, or successive sanding may have exposed the tongue and groove joint. To repair:

• individual boards can be lifted and replaced with matching boards sourced from a demolition yard
• floors in poor condition can be lifted and new materials laid, or can be overlaid with a timber flooring overlay.

If repiling has to be carried out from above, the boarding can be preserved by removing four or five rows of boards for their full length and replacing them on completion.

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Adding insulation

If the floor is uninsulated, it will be beneficial to install polystyrene or bulk insulation suitable for use in subfloor spaces. Where foil has been installed, it is beneficial to remove the foil and replace it with insulation. Be extremely careful with existing foil insulation because it may be electrically live if a steel fixing has gone through a live electrical cable. Several people have died from electrocution by contacting live foil. Look at NZECP 55 (NZ Electrical Code of Practice 55) for guidance on removing or working around existing foil insulation. Installing and repairing foil underfloor insulation was banned on 1 July 2016.

Reducing subfloor moisture can also make the villa feel a little warmer by keeping the air dryer.