Timber slat decks – decking slippery when wet

Cause

A smooth decking surface – the grooved decking timber is very worn, or non-grooved decking was installed

Repair

  • the easiest and lowest-cost solution will be to coat the deck with a non-slip coating. Proprietary non-skid paints and other coatings are available, but sprinkling clean, dry sand over freshly-applied paint before it dries is also an option

  • another solution is to replace decking with grooved decking timber perpendicular to the usual line of travel

  • common decking timbers include H3.2-treated radiata pine, kwila, vitex (also known as vasa), cypress species (particularly macrocarpa) and jarrah, an Australian hardwood. Composite decking is also available, manufactured from recycled plastic (HDPE) and waste timber fibre

  • install timber decking with a 12 mm minimum gap between the building cladding and decking for drainage and maintenance, 3–6 mm gaps between decking timbers lengthways and 1–2 mm gaps at butt-jointed ends

  • follow the fixing recommendations of the decking supplier. In general you can use hot-dipped galvanised steel nails and screws to fix the decking, except where timber has been treated with ACQ or CuAz preservative, in which case stainless steel or silicon bronze fixings must be used to ensure durability. Stainless steel nails should be annular grooved to provide sufficient withdrawal resistance

Cause

Grooved decking was installed parallel to the usual path of travel

Repair

  • the easiest and lowest-cost solutions will be to install anti-skid strips across the decking or to coat the deck with a non-slip coating. Proprietary non-skid paints and other coatings are available, but sprinkling clean, dry sand over freshly-applied paint before it dries is also an option

Cause

Moss has grown on the decking

Repair

  • the growth of moss indicates that the decking is remaining wet for long periods. Address this if possible. Repair any gutter damage that may result in water spilling onto the deck, or trim back vegetation that is preventing air movement from drying the timber

  • clean decking by washing using a stiff bristle brush with water and a mild detergent and rinse thoroughly. A solution of 1 part of household bleach to 4 parts water can also be used if necessary and rinsed off. Be aware that this can damage garden plants and should not go down stormwater drains. Proprietary cleaners (including some that destroy fungi and moulds) are also available

  • do not use a high-pressure water blaster on a timber deck. The pressure can damage timber fibres, affecting appearance and leaving the timber more vulnerable to damage

Cause

Dirt has built-up on the decking

Repair

  • clean decking by washing using a stiff bristle brush with water and a mild detergent and rinse thoroughly. A solution of 1 part of household bleach to 4 parts water can also be used if necessary and rinsed off. Be aware that this can damage garden plants and should not go down stormwater drains. Proprietary cleaners (including some that destroy fungi and moulds) are also available

  • remove mould as soon as it becomes visible – left for a long time, some moulds can stain decking timber

  • do not use a high-pressure water blaster on a timber deck. The pressure can damage timber fibres, affecting appearance and leaving the timber more vulnerable to damage