5 minute read
Cost, maintenance and longevity - the balance
Timber specialist, Robin Schultz on site with his team.
Contour Decks
Gareth Griffiths
Timber construction has been around for a long time and has often stood in the shadow of brick and concrete forms of construction. However, there is one area in which timber has clear dominance, the decking and pedestrian walkway area.
With the upswing in the use of exotic hard timbers, as opposed to SA Pine, we decided to approach timber expert Robin Schultz, about what the building owner or project manager might do when faced with different options.
Can you share with readers the range of different timbers available and what you would recommend? The type of decking material specified is largely dependent on foot traffic. Commercial decking usually
has more foot traffic than domestic applications. In high traffic areas, we would recommend the use of hardwoods.
Are there any climate conditions that make a particular type of timber a good recommendation? In our experience, it is not necessary to specify one kind of timber vs. another according to climate. However, where high humidity occurs, decking should be rinsed down and rubbed with a medium bristle brush at least once a month to remove dead algae build up.
What are the types of timber available and what are the relevant cost considerations in each case? Often the client will specify what timber is required. It is
important to note that the cheapest is not always better. Note, the practice is to coat SA Pine timber, or to use a thicker cut, which increases the cost.
Decking timber type Cost for 19mm Cost for 32mm with coating SA Pine Radiata species $ $$$ Cladocalyx $$$ N/A* Macaranduba $$$ N/A* Garapa $$$ N/A* Balau $$$ N/A* IPE (Brazilian W alnut) $$$$$ N/A*
*Some timber may be left uncoated. See ‘Should timber be treated’, below.
Battery Park Canal Bridge – Cladocalyx Decking.
What are the fastening and fixing systems do’s and don’ts? I recommend the use of traditional fixing and fastening methods. These are the general guidelines: • The preferred screw will be a high quality 304 CSK (counter sunk stainless steel) with a “Torx” head and reinforced head to shank intersection. If the head of the screw is not reinforced, the head will crack off from stress rendering the installation a disaster • W e never recommend the use of small headed screws, secret fixing methods, side fixing, deck clips, nails and/or double threaded screws. Traditional methods work best. It does not make sense to cut cost at this level, against the big investment on timber. • The screw length should be at least 2,5 times the thickness of the decking board. Two screws should be positioned per board across the face on every joist. • The screw should have a head of at least 10mm in diameter and should securely hold the decking board onto the substructure. • Over tightening will result in the thread stripping in the substructure, resulting in decking boards warping beyond recovery • The pre-drilled hole in the decking board needs to be slightly larger than the outer thread diameter of the fastener being used.
Cape Town Convention Centre – Macarandube Decking.
• Full threaded fasteners are not recommended as they can cause the decking board to “climb” up the screw.
Any general advice to the installer? Counter sink the top of the screw head 1mm lower than the board. If the screw head is countersunk too deep, a small pool of water will accumulate every time it rains, which swells the wood around the screw and ultimately leads to screws loosening over time with constant swell / shrink movement of the timber.
V&A Waterfront – Garapa Decking
Should timber be treated with a coating or oiled? Soft woods by nature are less dense. By volume the density is less than hardwood. Soft wood will absorb more moisture and dry out more readily than hardwood. Hence hairline cracking is more prevalent. Stains and sealants are short term aesthetic solutions. As outdoor SA Pine is CCA treated against fungus and rotting it will last without the need for a decorative coating, however if decorative coating is considered by the client then they should be re-applied often to protect the surface from ultraviolet light degradation. • Hardwood decking may be thinly coated with very light mineral oil to slow down acclimatisation and stress cracking. • We do not recommend linseed oil as it simply too thick and remains sticky after application.
The final word is quality A class one hardwood deck should give you many years of trouble free service if installed correctly. It is highly advisable to vet your installer’s experience in hardwood decking installations to ensure you get value from the project you are investing in. After all, a badly or poorly installed deck cannot be rectified using the same materials over again.
Robin Schultz of Contour Decks is an active decking and walkway installer and has delivered many successful projects over the years, large and small scale. These range from domestic installations, to commercial installations that include the CTICC2 extension; to approved boardwalks for nature conservation authorities. He may be contacted on 082 444 5954 should readers have any queries.
Steenberg Estate – Balau Decking.
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