Timber floorboards – borer

Cause

Damp flooring due to high internal or sub-floor moisture

Repair

  • if there are high internal moisture levels:

    • avoid using unflued gas heaters and avoid drying laundry inside – these add a lot of moisture to the air

    • opening windows for at least 10 minutes every day can make a difference to indoor air quality

    • increase the amount of ventilation provided. In particular, add a rangehood over the kitchen stove and an exhaust vent near the shower in the bathroom, both vented to remove steam to outside the house. An alternative to reduce bathroom steam is to fit a proprietary plastic dome over the shower to keep the steam inside

• if there are high sub-floor moisture levels:

    • identify the cause of the subfloor moisture and address it. If it is caused by a leaking pipe, make a repair, or call a licensed or certifying plumber to repair it. Work on waste pipes and drains must by law be carried out by a licensed or certifying plumber

    • if surface water is flowing under the house, lower the ground levels around the building and slope the ground away from the house. Install channels or sub-surface drains and discharge into a stormwater drain or soak pit 

    • lay polythene sheeting at least 0.25 mm thick to cover the ground under the house. Ensure that the ground is shaped so no water accumulates on the polythene. Polythene sheets should be lapped a minimum of 150 mm, preferably taped, and butted up to foundation walls and piles. Weigh down the sheets with bricks or concrete to avoid them being displaced by air movement

    • improve subfloor ventilation

  • if the borer infestation is active, treat infested timber with a residual insecticide by brushing on or spraying surfaces, ensuring that flight holes are drenched or preferably injected. Using a small spray nozzle to inject the liquid into the holes is effective, but wear eye protection as the spray may shoot out another hole towards you.

  • if the infestation is extensive or fumigation is being considered, consult a specialist pest destruction firm that is a member of the Pest Management Association of New Zealand

  • borer holes in floorboards are unlikely to result in major damage. The decision to replace infested timber is usually based on aesthetic reasons –  whether the appearance of borer holes is acceptable or not

Cause

Use of untreated or sap timber floorboards

Repair

  • if the borer infestation is active, treat infested timber with a residual insecticide by brushing on or spraying surfaces, ensuring that flight holes are drenched or preferably injected. Using a small spray nozzle to inject the liquid into the holes is effective, but wear eye protection as the spray may shoot out another hole towards you.

  • if the infestation is extensive or fumigation is being considered, consult a specialist pest destruction firm that is a member of the Pest Management Association of New Zealand

  • borer holes in floorboards are unlikely to result in major damage. The decision to replace infested timber is usually based on aesthetic reasons –  whether the appearance of borer holes is acceptable or not