This wooden sun deck we designed in Durban was a low level sun deck which was barely off ground level. We were taking it flush away from the level of the floor with the living room and extending it outwards in to the lawn. The grass was not growing successfully within this section because of large trees that ended up leading to a sizable shadow so the client required to deck it to shed the trouble.
The greatest issue when establishing a wood deck near or on ground level would be to get a support beam underneath the joists where essential. There are two ways a person can use. The first is what I name the cleat and beam application wherein a beam is positioned underneath the joists to provide them their support. We generally utilise a 38 x 114 joist and a 50 x 228 beam. One has to span the 38 x 114 to a maximum of 2m but 1.8 is preferable. So every 1.8m to 2m one must slot an under beam under so as to support those joists. Posts should be applied every 3m on the 50 x 228 beam. With this specification one can conserve on timber whilst still supplying satisfactory support to ensure the sundeck is structurally strong.
The issue with this procedure arises because if you have a 228 beam, plus a 114 joist and then a 19mm deckboard on top of that your overall height required above surface level is 361mm. If the deck is too close to ground it is going to mean excavating soil to be able to drop that beam down enough to still arrive at the original height of your sundeck. Although this is quite attainable and not that too time consuming, it often results in the main beam sitting in soil or it could possibly come into contact with wet soil over time. One has to as a result use a minimum of H4 CCA Treated SA Pine as the beam and in fact that total substructure ought to be H4, though the joists aren’t in contact with soil, to ensure that no rot will occur.
The other method is to create a frame, all in the same plane using 38 x 114 and use no under beam. This will result in the deck only being 133mm in height so that no excavation will be needed in order to bring the deck up to the required height. However now that you don’t have a beam to attach posts to, you will need to attach the posts to the joists and fascia beams. Again this is not a problem, but it will require a few more posts than in the first method as you can only span your 38 x 114 to a max of 2m. Hence more posts, more concrete and more labour in digging holes.
We used the joist and beam system here as we had enough space below to set the beam without having to dig too far into wet soil. So our work was made lighter by not having to dig too many holes.
Once the substructure is up, the deckboards can go down. On this wooden deck we used 19 x 68 balau deckboards. We used two deckboards as a fascia to cover our joists and beams, filled our holes with epoxy, sanded and sealed.
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