Build a Timber Deck Over Concrete

Build a timber deck over concrete

Concrete is a versatile and durable flooring material, but in time it can end up in pretty bad shape. How do you add life to a tired, old, cold and dull slab of concrete? Why not build a timber deck on top of it?

The principles of laying a timber deck over concrete are pretty much the same as that of constructing conventional decks, but there are a few important differences you need to consider.

  • First you need to make sure that you have enough room beneath your door to allow for the battening and the thickness of the decking boards. Otherwise your door may fail to work if it needs to open outward.
  • You cannot simply screw decking boards directly to the concrete slab itself. You need to have battening in place for the decking to sit on. This allows air to flow through the structure and it helps to level the height. The battening also protects the timber from direct contact with the chemicals in the concrete, which can cause the timber deck boards to rot quickly.
  • Position the battens at 450mm centres. You may also discover that your existing slab has a slight fall-in it for water to run off. To counter this you will need to level this out with packers such as fibre cement sheeting.
  • If there’s too much height to use battens, you can use regular joists in their place and  anchor small stump posts with bolt down post shoes or brackets to bring the height to where you want it.
  • When laying battens and fibro sheeting packers, allow some spaces along the length for water to naturally run out so it doesn’t pool against the packers.
  • If you are fixing the battens through the packers into the slab, try using galvanized countersunk masonry bolts, or concrete wall plugs, screwed in at 600mm intervals.
  • Fix the decking to the battens with a 4mm gap between the boards and then finish off the ends with decking boards down the sides. This further complements the look of the deck. Using countersunk stainless steel decking screws will also give it a nice touch without having to use a nail gun. Remember to adjust the torque on your cordless drill to avoid damaging or rounding the screws.
  • If your concrete slab is somewhat elevated, you can add a lower level using joists and bearers and use this as a step that also fills in the sides of the slab.

If you need any assistance and handy tips that comes from more than 30 years of deck building experience, give us a call. The friendly staff at Softwoods are only too happy to help.


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Attached gable pergola with timber liningIronbark deck over sloping site with inbuilt stairs and stainless steel balustrade

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