We built this wooden balau deck in Plantations Estate in Hillcrest Durban recently for a client.
We needed to excavate a few hundred mm down in order to give us enough space in which to install our timber substructure. It is quite important to remove enough soil when building low-level wooden decks on top of soil. This is to give the deck enough space between the bottom of the timber substructure and the top of the soil so that the timber remains relatively dry. It is very important not to allow the timber to touch the wet soil unless it is H4 CCA Treated. CCA Treatment has various Hazard Classifications and each one is associated with specific applications. There are various articles on this site on the topic. You can find them by searching CCA in the search box at the top right of the screen. As a quick summary, H3 is good to go outdoors with periodic wetting and H4 is good to live in the ground in constant contact with wet soil. This is all according to www.sawpa.co.za. So if you are using H3 CCA Treated make sure there is sufficient space below to ensure the wood doesn’t touch the soil. If you are using H4 then it is ok to bury the timber in the ground.
Having said that the more space below the deck the better to allow air movement and keep as much moisture away from the balau deck boards which are not treated. Although balau is a very hardy wood and can withstand a certain amount of wetting, the more moisture around, the quicker the wood will deteriorate.
People often ask me about treating the pine before it goes in the ground or before we install deck boards above. There is no need. The pine is all pressure treated to the correct Hazard Classification and therefore no more treatment or sealing is necessary. In fact there is argument that coating it with, for instance bituseal, will in fact allow water in but won’t allow it out. Water will find a way in. A small stone scratching the bituseal off during installation, or a bump here and there, will allow water in and it won’t easily find its way out. Leaving it so the water can flow in and out quickly will result in a drier piece of timber for longer. There’s no need to do anything to your CCA treated timber.
Balau deck boards are then installed on the surface simply because balau is more stable and won’t crack, twist or warp as easily as pine. The cost difference between pine deck boards and balau deck boards is minimal, if anything. If you use pine deck boards you will use twice as much wood and although pine is relatively inexpensive, for deck boards you will need to use S7 (semi clears). The cost of semi clears negates any saving between pine and balau. Stick with balau as a deck board. It’s very stable. As a substructure, it is not cost-effective to use balau and S5 (industrial grade) pine can be used there at a much lower cost that both balau and semi clear pine.
This deck was left to grey naturally by leaving it as is. No oil, no sealer, nothing. Just leave it and periodically pressure wash it to remove any grime or dirt. If you choose to oil your deck then use an oil. Don’t use a product that will dry on the surface. If it dries it will peel and flake.
For a no obligation quote on building your wooden deck please use the contact us form below or you can contact us on 082 496 5444. We also offer a DIY service. We will supply you with all the correct materials you need to build your own deck and can advise on time-saving tips and tricks as well as recommended building practices.