Spring is in the air and our decking sales are going crazy. Here are some tips when it comes to doing a deck. (this is by no means a complete guide but rather only be used as a good reference point.)
- Usually, 38 x 152 or 50 x 152 S.A. Pine H3 Timber is used, but this must be specified and designed by a competent person for safety reasons. For ultimate lifespan, a hardwood substructure such as Piqua or Garapa can be used but this is costly.
- Joists should be spaced at 350 to 450 intervals and off the ground.
- Noggins should be used between the joists to keep the joists square and rigid while CCA H4 treated pine poles or hardwood posts should be used to support the load and prevent the joists from deflection.
- Joist hangers are used to secure the ends of the deck to a wall but should not be relied on to be load bearing.
- There must be sufficient ventilation under the deck, particularly in damp areas when installing the substructure. Without ventilation, the decking planks, particularly the wider 140’s will ‘cup’ up. Cupping is caused by the underside of the decking planks remaining damp due to lack of ventilation while the top side dries.
The deck and securing thereof
- Use a good quality decking plank. Kiln-dried (KD) is preferred over air-dried (AD).
- 4 to 5 mm gaps should be used for the 90mm decking plank while 8 mm to 12mm gap should be used for the 140mm plank. There will be some expansion & contraction depending on the season so appropriate spacing is essential. A proper spacer tool should be used not only to ensure consistency of the gaps but also to pull the planks perfectly straight.
- There must be at least 2 stainless steel screws per fixing at 350mm to 450mm intervals onto the substructure. Each stainless steel screw fixing should be 12mm in from the edge of the decking plank to prevent splitting. Under no circumstances can the deck plank be secured with one screw as this will cause the deck to ‘cup’. The holes for the screws should be pre-drilled 2mm oversized (otherwise decking ends will split), and the screws should be countersunk (otherwise when the deck shrinks the screws will be exposed).
- The stainless steel screw should be ideally a 5 x 60 but 5 x 50’s are used too. For the wider 140mm, we do highly recommend the 60mm. Please contact us to ask what the appropriate decking screw should be.
For best results
- We suggest with all decking; especially Garapa (cement stains Garapa) should be regarded as a finishing product so do not install it if paint, plaster or any other labor work is still to be done in the area.
- Oil treatment should be used on the deck once the deck is installed and cleaned to help maintain the deck and minimize surface cracks, splintering, cupping, and crowning. Please contact Online Building for advice on cleaning your deck and the best oils to use.
- Lastly, it’s important to remember your timber deck is a natural product so as your deck weathers, expansion and contraction will happen and small cracks are likely to appear on the surface of your deck. This is caused by intermittent wetting and drying of the deck and is part of the character of the timber but has no structural effect on the deck whatsoever.
Please do not hesitate to contact Online Building on 021 712 1550 for any further questions.
Disclaimer: Online Building cc cannot be held liable for any decisions made based on the advice given. Under the ECT Act and to the fullest extent possible under the applicable law, Online Building disclaims all responsibility or liability for any damages whatsoever resulting from the use of this site in any manner.