Fence posts cracked/damaged

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 deep into ground

Repair

  • replace cracked or damaged timber posts with new H4-treated posts

  • make sure the posts are no more than 2 m apart (or 1800 mm in windy locations)

  • 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 places 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. A good shelter fence should have about 40–50% of its 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 and appropriate for most fences up to 2 m height, but larger dimensions can be ordered from some suppliers

  • make sure the posts are no more than 2 m apart (or 1800 mm in windy locations)

  • 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 places will improve stability. Brace the posts in position, checking they are plumb and the faces are flush before pouring the concrete

Cause

Impact damage

Repair

  • replace posts as in the repairs above