Timber boarding, veneered MDF or plywood – black staining

Cause

Evidence of mould growth due to condensation 

Repair

  • check that there is insulation in the ceiling space and under the floor. If not, add insulation. See the website www.level.org.nz for more details. There may be funding available to help with the cost

  • 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

  • opening windows for at least 10 minutes every day can make a difference

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

  • sand timber to remove staining or wash surface with proprietary cleaner to remove any mould/mildew. Treat with fungicide before recoating

Cause

Leak in the wall

Repair

  • first, locate and repair the leak in the wall. Where it is suspected that there is more than one leak, leaking is extensive or the leak cannot be found, engage an experienced building surveyor for advice

  • sand timber to remove staining or wash surface with proprietary cleaner to remove any mould/mildew. Treat with fungicide before recoating

  • ensure there is good heating and ventilation in the house. Avoid using portable (unvented) gas heaters. Install insulation if the house is not insulated