Loose wedges between pile and bearer

Cause

Timber shrinkage due to use of green (wet) timber during construction

Repair

  • always tell someone when you are going to work under a floor. Make sure you take a torch with you and if possible a phone

  • first, determine that the bottom of timber piles are sound. Piles that are rotten, loose in the ground or on a pronounced lean should be replaced with H5 treated timber piles (or precast concrete piles). Where there are very large gaps between pile and bearer – more than 100 mm – the pile should also be replaced

  • use wedges/packers with a minimum H3.2 treatment, and brush treatment onto any cut surfaces. The packers should be cut so they are a tight fit and they cover the whole width of the pile and the whole width of the bearer above them

  • put damp-proof course between the pile top and the packers (especially with concrete piles and piles under 150 mm high above ground)

  • once packers are in place, nail with 75 x 3.15 mm nails. Nails should be hot-dipped galvanized, or stainless steel nails in coastal locations or where the top of the pile is less than 600 mm above the ground

  • make sure piles are fixed to the bearers. With timber piles, fix 25 mm x 1 mm galvanised steel straps on either side. With concrete piles, pass a 4 mm galvanised wire through the hole in the top of the pile. Pull each end of the wire tightly over the top of the bearer and fix in place with galvanised steel staples. In coastal locations or where the floor is close to the ground use stainless steel fixings

  • if the floor needs to be relevelled, consult a chartered engineer or a registered building surveyor for advice. You can also check out the videos on jacking up a foundation and packing house piles on the MBIE website.

Cause

Wedges were not tightly inserted or were not nailed in place and have become loose

Repair

  • follow the repair above

Cause

Pile has rotted 

Repair

  • you can check for rot in timber piles with a long-bladed screwdriver. Try to push it into the timber just below the ground surface. If the screwdriver easily enters the timber, then the timber is rotten

  • all rotten piles should be replaced. 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). Extensive 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

  • if the floor needs to be relevelled, consult a chartered engineer or a registered building surveyor for advice. You can also check out the videos on jacking up a foundation and packing house piles on the MBIE website.