Pole foundations – bearer and/or joist damage/deterioration
Listed under: timber and wood-based, electrical, plumbing, pipes, timber, Subfloor, framing, poles, wires, durability, borer, rot
Cause
Timber sizes were too small for the span/loading
Repair
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the bearer and/or joist must be strengthened or replaced with timber of the appropriate size to provide the support/bracing required
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engage an architect, designer or chartered professional engineer to calculate the repairs/replacements required
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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
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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
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the BRANZ Bulletin BU597 Timber pole house construction may be helpful
Cause
Timber has rotted
Repair
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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
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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
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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
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the appropriate repair depends on the level of damage to the bearer or joist
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where the bearer or joist still provides adequate support it may be possible to fix a proprietary metal support in place
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it may also be possible to fix timber plates treated to a minimum H1.2 to either side of the defective timber
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in extreme cases the bearer or joist may need to be replaced
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engage an architect, designer or chartered professional engineer to calculate and plan the repairs/replacements required
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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