Pole foundations – bearer and/or joist damage/deterioration

Cause

Timber sizes were too small for the span/loading

Repair

  • the bearer and/or joist must be strengthened or replaced with timber of the appropriate size to provide the support/bracing required

  • engage an architect, designer or chartered professional engineer to calculate the repairs/replacements required

  • where the bearer or joist is sheltered from the weather but exposed to the ground atmosphere, it must be treated to a minimum H1.2 and a minimum 150 mm clear of the ground

  • replacing damaged bearers falls into the category of ‘restricted building work’. If you are paying a tradesperson to do the repair/replacement work, they must be a licensed building practitioner with a foundations licence

  • the BRANZ Bulletin BU597 Timber pole house construction may be helpful

Cause

Timber has rotted

Repair

  • you can check for rot in timber with a screwdriver. Try to push it into the timber and if the screwdriver easily enters the timber, then the timber is rotten

  • rotten bearers or joists should be replaced with new timber treated to minimum H1.2. If just one part is affected, replace the affected area and at least 1 m either side of the rot. In many cases it may be a better option to replace the whole member

  • work on foundations (which includes bearers) falls into the category of ‘restricted building work’. If you are paying a tradesperson to do this, the work must be carried out or supervised by a licensed building practitioner with a Foundations licence

Cause

Borer infestation in timber

Repair

  • as for first repair above. Ensure the replacement timber is treated to a minimum of H1.2

Cause

There is excessive notching or drilling through the timber for pipes or wiring

Repair

  • the appropriate repair depends on the level of damage to the bearer or joist

  • where the bearer or joist still provides adequate support it may be possible to fix a proprietary metal support in place

  • it may also be possible to fix timber plates treated to a minimum H1.2 to either side of the defective timber

  • in extreme cases the bearer or joist may need to be replaced

  • engage an architect, designer or chartered professional engineer to calculate and plan the repairs/replacements required

  • replacing damaged bearers falls into the category of ‘restricted building work’. If you are paying a tradesperson to do the repair/replacement work, they must be a licensed building practitioner with a foundations licence

Cause

The floor is overloaded

Repair

  • as in the first repair above