Fence not vertical
Listed under: timber and wood-based, timber, Section, fences, durability, rot
Cause
Timber posts rotting in the ground
Repair
-
replace timber posts with H4-treated posts (or H5 where available)
-
if the ground is wet or boggy for long periods, consider improving site drainage by installing slotted drainage pipes under the surface. Flexible and solid proprietary products are both available. These should be installed in trenches lined with gravel and should slope downwards approximately 10 mm for every 100 mm of length. The excess water should drain to a soak pit or a stormwater system
-
if constructing a soak pit, follow the guidance in New Zealand Building Code Verification Method E1/VM1. Be aware that construction of a soak pit may require a building consent
Cause
Posts not anchored sufficiently deeply into the ground
Repair
-
take the fence down and dig up the posts. Determine which are in good enough condition to be reused. Replace damaged timber posts with new H4-treated posts
-
make sure the posts are no more than 2 m apart (1800 mm in windy areas)
-
dig holes a minimum 750 mm deep for the posts (or in windy locations, a minimum 100 mm deep for each 200 mm of post above ground)
-
concreting the posts in place will improve stability. Brace the posts in position, checking they are plumb and the faces are flush before pouring the concrete
-
completely solid fences take the full force of the wind and create downwind turbulence. Fences built for shelter should have about 40–50% of their face area open and be constructed with gaps
Cause
Posts not big enough for fence height
Repair
-
replace fence posts with H4-treated posts of sufficient size and length. 100 x 100 mm is a standard dimension for posts, which is enough for most fences up to 2 m height, but larger dimensions can be ordered from some suppliers. Posts of 3 m and more are commercially available throughout the country.
-
make sure the posts are no more than 2 m apart (1800 mm in windy areas)
Cause
Impact damage
Repair
- replace posts as outlined above
Cause
Tree roots are moving the fence foundations
Repair
- the tree roots are likely to be a significant size if they are having an impact on the fence posts. One option is to relocate the fence, or at least the posts. If you wish to retain both the tree and the fence, seek the advice of an appropriately trained/experienced arborist, such as an approved contractor of the New Zealand Arboricultural Association, about whether the roots can be cut