Balau vs CCA Treated Wooden Deck Durban

I often get asked about using balau as a substructure in a wooden deck. There are various pros and cons of using balau as a substructure in your wooden deck so I thought I would jot it down and in future I can direct clients here who want the ins and outs of using balau as a structure for your wooden deck.

Balau is a very good, hardy and durable wood to use in outdoor wooden decks and other outdoor projects. It contains toxins that limit insects eating it and it is high in resins and oils which naturally repels water and limits rot. All wood will eventually rot. It is just that some will rot quicker as they are less dense and less oily which means they will absorb water more easily, which remains in the wood, causing fungus to grow which breaks down the fibres in the wood and is commonly called rot. This is a simplified explanation but I think it delivers the message accurately. Water doesn’t cause rot. Fungus, as a result of water and sunlight, causes rot.

Balau therefore will rot and I have started documenting some pics of rotten joists that I have come across in my repair work of wooden decks. It may take 15 years for this rot to start but it will happen and when it does repair work can run into thousands if not a complete deck rebuild. Joists are often difficult to access whereas deck boards are not.

On the other hand a piece of wood that has been chemically treated to prevent, or limit rot, will last a lot longer and a pre determined life span can be calculated.

CCA Treatment is a process of pressure treating SA pine. A vacuum is created in a chamber that contains the pine and a solution of copper, chrome and arsenate is introduced which then takes up the void created by the vacuum sucking the solution into the cells. The copper prevents fungus growing which in turn prevents rot, the arsenate keeps the insects away and the chrome binds the two to the wood so that I doesn’t leach out.

Balau is too hard and dense to treat. Pine is a commercially grown timber in South Africa which is inexpensive and very suitable for treatment as it is soft and takes up the solution of CCA successfully. There are various different Hazard Classification or H classifications. Basically H2 is good for indoors (roof trusses etc.) H3 for outdoors exposed to the elements, H4 for in constant contact with wet soil. H5 for submersion in fresh water and H6 for submersion in salt water. A correctly treated piece of pine to H3 will, as per SAWPA guidelines, last in excess of 50 years which is pretty impressive in comparison to a piece of balau that comes with no fixed life expectancy. A poor quality piece of balau may start to fail within 5 years whereas a good quality piece may only start in 15 years. Most of the pics I have documented here are of decks that range in age from 8 years to 15 years. But generally speaking I have found some rot setting in all the decks of 15 years or older.

S5 (SABS Structural grade) Pine is considerably cheaper than balau structural timber. So from an economic point of view it makes sense to use pine in place of other woods wherever possible.

One might now ask why is pine not used on the surface of a deck? Why is balau preferred?

Balau is a very stable wood and therefore expands and contracts less than pine. It is about twice as dense, knot free and doesn’t twist and warp as easily. Pine is soft and with the sun beating on the deck it will tend to crack, twist and warp more easily. To use pine as a deck board one needs to use a 38mm board as opposed to a 19mm board in balau (twice as much wood). Also pine deck boards are normally manufactured from S7 as opposed to S5. S7 refers to the number of knots per square inch (or centimetre) and is therefore a lot more expensive than S5. The cost of pine deck boards is in fact a few rand more per square metre than balau. Hence the reason to use correctly treated CCA pine as a substructure and balau as deck boards. Again pine doesn’t work well in balustrades because twice as much wood needs to be used at S7 grade.

For a free no obligation quote on your sun deck, pool deck, balustrades, pergolas etc., please call us on 082 496 5444 or use the contact us form below.

Wooden Sundeck Constructed in Toti Durban

This wooden sundeck we constructed in Durban was a low-level deck which was barely off ground level. We were taking it flush off the level of the floor in the lounge and extending it outwards into the garden. The grass was not growing properly in this area due to large trees that were creating a large shadow so the client wanted to deck it to eliminate this problem.

The biggest challenge when building a wooden deck near or on ground level is to get a support beam underneath the joists where needed. There are two methods one can use. The first is what I call the cleat and beam system whereby a beam is placed underneath the joists to give them their support. We normally use a 38 x 114 joist and a 50 x 228 beam. One needs to span the 38 x 114 to a maximum of 2m but 1.8 is preferable. So every 1.8m to 2m one needs to slot an under beam below so as to support those joists. Posts should be used every 3m on the 50 x 228 beam. With this spec one can save on timber while still providing adequate support so that the deck is structurally sound.

The problem with this system arises because if you have a 228 beam, plus a 114 joist and then a 19mm deckboard on top of that your total height needed above ground level is 361mm. If the deck is too close to ground it will mean excavating soil to be able to drop that beam down enough to still arrive at the original height of your deck. Although this is quite possible and not that too time consuming, it sometimes results in the main beam sitting in soil or it may come into contact with wet soil over time. One must therefore use at least H4 CCA Treated SA Pine as the beam and in fact that whole substructure should be H4, even 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.

For a free no obligation quote or advice on your deck or other outdoor timber construction please call us on 082 496 5444 or use the form below to contact me.

Wooden Deck Built in Durban North – November 2011

Wooden deck Durban

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This was a normal wooden deck in the normal cleat, beam and joist system with a cleat attached to the wall on the house side, joists running off that perpendicular to the house and a main beam supporting the joists. This deck was built in the days when I was still sing balau as a substructure which made it relatively expensive. I have since started using at least H3 CCA Pine as a substructure. As mentioned in a previous article there is really no need to use balau as a substructure. Provided one uses the correct Hazard Grade (H grade) of CCA Treated Pine then the manufacturer of the chemicals used in the treatment process will guarantee that timber for up to 50 years. So there is a very strong argument that H3 CCA Pine will actually outlast balau because balau is not treated and will eventually rot although it will take a very long time.

H3 should be used where the timber is exposed to the elements (rain and sun) and H4 where it is buried in the ground or in constant contact with wet soil. H2, which is commonly purchased from your timber yards, should NEVER be used in decking and should only be used as roof trusses or other applications where it will not get wet that often.

Wooden deck Durban

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The wooden deck was a normal rectangle with a slight deviation towards one side to create a triangle so as to meet flush with the corner of the house. We used 90 x 90 balau posts to support the main beam and resting on top of the concrete surface below. These posts had a 12mm hole drilled from below up into the posts and then a re-bar was inserted with epoxy and the same done into the concrete floor. This prevents the posts from moving sideways. There is no need to dig these posts in as they can rest successfully on the surface of the concrete. A shoe was cut from timber in order to secure the main beam to the wall of the house. It is really just a piece of timber that is notched to accommodate the beam and the shoe is then secured to the wall using sleeve anchors. The beam then rests in this shoe and cannot move sideways or down. The weight of the deck of course prevents it from lifting up plus it is screwed into the shoe.

The balustrade was interesting as it was not the normal picket style you see in most other articles. It was the criss cross design with a box in the middle or Tahitian style as it is often called. We also carried this style of balustrade down the stairs. One can sometimes switch to picket style as one goes down the stairs and return to Tahitian style on the flat surfaces. We needed to adjust the angles slightly as we turned the corner down the stairs in order to get the balustrade in the correct plane.  We also built a gate at the top of the stairs which could be latched closed or even locked.

Wooden deck Durban

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It was sealed using a Timberlife Satin Wood Base 28/28 product which is a timber preservative that soaks into the timber rather than drying on the surface. Maintenance is therefore easy in that it can never peel or flake as it has soaked in and not dried on the surface. Simply clean it and apply two or three more coats. No more sanding, EVER.

For a free no obligation quote or advice on design of your wooden deck, please complete the form below or call us on 082 496 5444.

Wooden Sundeck Built in Gillitts – April 2013

Timber deck builder Durban

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This was our second deck we built in Durban using CCA pine as a substructure. I can confirm that there is a substantial cost saving using pine as a substructure and provided it is CCA treated to the correct Hazard Level (H level), then it is guaranteed by the supplier and manufacturer against rot and insect infestation for up to 50 years. So at least H3 must be used which is good for outdoors, exposed to the elements and if there are parts of it that are making contact with ground then H4 is better. In fact the cost difference between H3 and H4 is so slight that I am tending to just use H4 throughout as a matter of course to err on the side of caution.

This deck extended from the house outwards about 5m. Half of that 5m length was on existing tiles and concrete so we placed batons of 38 x 76 and the rest of it dropped down about a metre onto soil. We chose 76mm as our width of baton because it brought us up to exactly where we wanted to be in terms of height of the deck in order to clear the bottom of the door. We therefore had very little space between joist and the tiles so there was very little packing to do. When we place batons on the ground as joists, we fix them using a hilti. The hilti is really just to stop the joist moving sideways and not really up or down as once the deck is built the weight of it keeps it from lifting up. However the hilti provides enough fixing power in both directions so sleeve anchors are not necessary. Often the ground on which you are fixing these batons / joists to, is not completely flat and in order to get the surface of the deck level, one needs to shim one end of the baton or joist. This results in one end being higher than the concrete ground level and as such a gap exists between the baton and the ground. Because these batons are relatively thin (between 38mm and 76mm) they are not strong enough in their width to support the deck. They therefore need to be packed with structural grout or a building sand / cement mixture to take up the gap between the baton and the ground.

Timber deck builder Durban

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The rest of the deck was elevated about 1m off the ground so from that point we installed 38 x 114 joists with a main beam running the width of the deck (parallel to the stairs in the picture). We set that back 300mm so that our span between beam and wall was only 1.9m which is the maximum I am happy to go with a 38 x 114 joist.  The rest of the deck was therefore cantilevered by about 300mm.

Deckboards went on without a problem, and we then built the stairs that you can see in the picture. We took a different approach to the stairs that we normally do, or have done in the past. In the past we have secured a beam all the way along the front of each riser. In this case we built treads and risers in line with each joist and then only on the front riser we fixed a fascia beam which was then secured to posts that had been set in concrete in the ground. It was much quicker than, and just as stable as our previous method. The structure that we built can be seen on one of the pics alongside.  The client wanted to leave the sides open as he is planting some indigenous plants alongside to cover the gap thus allowing his access beneath the deck if need be, but once the plants grow they will cover the sides.

Timber deck builder Durban

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This deck was left unsealed as the client wanted the greying effect. I will re-visit it in a few months’ time and if the client is agreeable we can bleach it and high pressure clean it in order to bring it back to its natural colour.

For a free, no obligation quote please complete the form below and I will contact you.  Or you can call us on 082 496 5444.

Sundeck Built at Pennington on the South Coast

Sundecks South Coast

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This was my first deck I built. I had been toying with the idea of building sundecks for some time, rather than trying to sell furniture which I had been making for some years. There simply isn’t a viable market to make furniture in South Africa unless one has large regular orders and a production line can be set up for a specific product. Saying that I still make the odd Adirondack Chair and picnic table, but my focus changed at that point to decking. Something that could not be imported and sold as flat pack.

I secured this job at a very cheap rate. It was in Pennington which was too far to commute each day so we stayed down there. With a crew that had never built a deck and myself who had studied it in theory only we proceeded to build.

We had to first remove an old deck that had been built using non treated pine which had rotted beyond imagination. It still annoys me to see decks being built out of non-treated pine. Some are often built from H2 treated pine where as they should be at least H3 but preferably H4 treated pine. I will go into more detail on that subject in a later article. Perhaps it is ignorance, and not a specialised deck building company doing the job, but there is a vast difference between the different grades of CCA Treated Pine.

Sundecks South Coast

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Nevertheless, we cut away at our rotten deck which was actually unsafe to walk on so it took some time to carefully remove all pieces and the joists. We left the post in tact as they were teak and were still very good. Once down we placed our cleat on the wall of the house, erected our main beam and set out our joists. There was a canter lever involved which worked well as we had increased the size of our joists to 40 x 140 so we could span them longer and canter lever longer than if we had used 30 x 102 joists.

The deckboards went down without a problem. Our balustrade had to match the neighbour’s balustrades as it was situated in a complex with other decks. It was a simple criss cross style balustrade so went down without much hassle and relatively quickly.
The biggest challenge on this deck was removing the old one which took us just over a full day. Removing a deck can be very dangerous, as you can imagine, and needs to be thought out carefully and taken down with extreme care so as not to damage buildings around it or result in injury to crew.

Sundecks KZN

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We made no money on this job because we had over sized most of our timber, the client had requested 21 x 72 deck boards which were a lot more expensive than the standard 19 x 68 boards and we had to factor in accommodation and food for a week while we built it. Nevertheless it was our first deck and we learnt a lot.

Wooden Sundeck Built in Forest Hills Durban

sundecks Durban

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This sundeck we built in Forest Hills Durban was an add-on to a deck we completed in 2012. The client initially built a 20 odd square metre deck off the front of his grant flat. It was then decided to extend the deck around the corner to tie up with the kitchen door.
We needed to decide which way the deck boards should run. Traditionally they should have run the length of the deck extension, but because of the way the existing deck had been built, it would have resulted in an odd line that would have been visually unappealing. Had the extension been built at the same time as the deck then the deckboards could have met at a 45° angle to turn the corner. Instead they would need to either meet at a 90° angle or they would need to run the same way (i.e. the width of the deck rather than the length). It was decided to run them the same way as the existing deck resulting in them running the width of the deck rather than the length.

With this in mind we set out to lay the substructure which consisted of long joists of about 9.2m. The width of the deck was 1.2m so we set 2 joists and a cleat along the wall. The challenge in setting such long joists of course is to ensure that they are set straight. Our joists were each 4.5m long so had to be joined in the middle without allowing them to bend or bow at the join. It was easier to join the joists beforehand, set a false deckboard of pine to hold them at their 1.2m width and then dig our holes for posts. We used H4 CCA gum poles as posts as they would not be visible from the outside and budget did not allow for balau posts. The poles were half checked to accept the joists, secured to the joists using kalgard 60mm screws and concreted in with 6 inch nails hammered into the base to prevent the post from sinking over time. A dry mix was used so as to be able to work with the post and joist immediately after setting them.

wooden decks Durban

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There was a concrete gas bottle plinth that was not decked and we had to deck around that and fill the vertical surfaces with balau cladding for aesthetics. Also the plinth that existed directly outside the kitchen door was slightly higher than we would have liked and as such we could not use our 30 x 102 joist and had to use a 30mm baton to arrive at the same height as the rest of our joists.
Once the substructure was down it was relatively plain sailing as our rough pre-cut balau deckboards were screwed down. We intentionally left them slightly long and after they were all down, snapped a chalk line along the edge and cut with a skill saw to get a straight line.

We cladd a few ends to close it all in, epoxied our screw holes to prevent water collecting in them and being soaked up by the end grain. Once dry we sanded flat and sealed using a top quality timber preservative with an oak tint.
A few pot plant stands were thrown in from the scrap off cuts which will now keep the pot plants off the deck and allow the water to drain away quickly and prevent accelerated degradation of the balau.

10m² took us 2 days to complete. The crew received a nice bonus based on square meterage and it was off to the next job.

For a free no obligation quote, or simply for an advice, please use the form below to contact me or you can call us on 082 496 5444.