Piled foundations – gap between pile and bearer
Listed under: concrete and cement, timber and wood-based, timber, Subfloor, bracing, framing, piles, moisture
Cause
Timber shrinkage due to use of green (wet) timber during construction
Repair
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Support the bearer with jacks and insert a minimum H3.2-treated timber packer the full width of the pile. Fix in place with 100 x 3.75 mm nails. Nails should be hot-dip galvanised, or stainless steel in exposure zone D, or in zones B and C where the top of the timber pile is less than 600 mm from the ground
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piles less than 150 mm high require DPC (damp-proof course) under the packers
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where the gap between pile and bearer is greater than 100 mm the pile should be replaced.
Cause
Pile has rotted
Repair
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you can check for rot in timber piles or other 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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all rotten piles should be replaced, following Section 6 of NZS 3604:2011 Timber-framed houses. Use H5 treated timber piles (or precast concrete piles). Replacing just a few old rotten wooden piles under a house with new treated timber piles in the same positions does not require building consent (but still needs to comply with the Building Code). If you get a contractor to do the job, repiling falls into the category of ‘restricted building work’ and must be carried out or supervised by a licensed building practitioner with a Foundations licence. Total or extensive repiling will require building consent.
Cause
Pile has sunk into soft ground
Repair
- Repiling is required, as in the repair above for rotten piles, but the excavation for the pile must go down to good ground.