Timber posts/handrails/balusters are rotten

Cause

Inadequately treated timber 

Repair

  • remove affected timber, cutting well back from the area of visible rot. It is often better to replace entire handrails/balusters/posts rather than trying to cut out rotted sections. Where a joint is made in a handrail, it should be made over a support (see drawing)

  • replacement handrails, balusters etc. (pinus radiata timber exposed to the exterior but not in ground contact) should be H3.2-treated. Timber should be at least SG8 (structural grade 8 for wet-in-service conditions) and SG6 for infill members

  • handrails should be a minimum 90 x 45 mm, fixed with 4/ 100 x 3.75 nails to each structural post

  • top and bottom rails should be a minimum 90 x 45 mm, fixed with 4/100 × 3.75 nails between or to inner or outer faces of structural posts

  • nails should be hot-dipped galvanized steel at the minimum, and stainless steel with annular grooves in exposure zone D (i.e. coastal areas with salt in the atmosphere). Fixings should also be stainless steel where timber is treated with Copper Azole or Alkaline Copper Quaternary preservatives

  • posts in ground contact must be H5-treated

  • this is a good opportunity to bring the barrier up to meet current requirements if it does not. Barriers for residential decks must:

    • be continuous where the fall height is over 1.0 m

    • be at least 1.0 m high

    • have openings that prevent a 100 mm diameter sphere passing through

    • have less than 15 mm gaps in infill panels

    • have the top of the barrier at least 760 mm above a fixed seat

    • have no sharp edges or projections.

Cause

Moisture has become trapped in the joints

Repair

  • As above

Cause

Timber at the end of its serviceable life

Repair

  • As first repair