Understanding the Decking Options for your Timber Dock

Posted on by RComstock
Southern Yellow Pine Decking

The main problem with traditional softwood lumber is that it wears out quickly. Specially milled softwoods can be designed to address this weakness.

Although numerous alternatives have become available since the early twentieth century when timber docks dominated the market, they remain a preferred choice for some, especially along certain seaboards.  For some the natural warmth and aesthetic qualities of timber along with ease of assembly and repair make timber a preferred choice.

As with all dock systems not all designs or manufacturers are equal. However, assuming all performance specifications are on par with each other, one of the key components that can greatly impact the service life of your timber dock is the decking.

Exposed to the elements and heavy foot traffic, a durable deck that holds up to daily wear and tear and occasional hard use will ensure you get the best return on your investment.  Unfortunately, the problem with most wood decks, even with pressure treating, is that over time the wood cracks, splits and splinters.  One of the reasons is that the sun dries out the top but not the bottom causing the board to curl like a potato chip.  The hard edges take the brunt of the foot traffic and over time breakdown and splinter leaving the wood susceptible to rot.

To avoid this problem some marinas opt for a hardwood material.  Although this can be a viable solution, even hardwoods have the potential to crack, split and splinter over time if not cared for properly – although usually much less than softwoods.  The main problem with hardwoods is the cost.  IPE decking is often three to four times the cost of traditional softwoods.

To get a better understanding of the different issues associated with timber decks and the options available, we spoke with Mark Johnson, General Manager of Bellingham Marine’s timber division.  Mark has been involved in the Timber Dock industry for close to 30 years.  He’s worked with several different manufacturers and has a background in Marine Technology and Construction with an emphasis on millwork and fabrication.

Q:  In your experience, what are the key factors that compromise the potential life of a timber deck?

A:  There are three main things that impact the life of a timber deck: UV or exposure to sunlight, expansion and contraction from moisture, and foot traffic.  Ultraviolet light and changes in moisture will cause timber to wear or weather. It will lose its natural color and fade to a silver/grey, its surface will become rough, and over time splits and cracks will develop. In high traffic areas the deck will wear more quickly, just as carpets do.  The area where you notice this the most is at the foot of the gangway, where you have the most traffic.

Q: Is switching to a hardwood deck a solution?

A:  Switching to hardwood is one possible solution to extend the service life of the deck but the pricing can often be prohibitive.

Q:  What other solutions exists?

A:  Aside from hardwood there are two other options – a composite decking material or specially milled softwood.  Price wise the composite is right in the middle between hardwoods and softwoods. The problem with composites is that they are extremely vulnerable to fluctuations in temperature.  There is also great variability in the performance of the composites available on today’s market and they don’t tend to have the strength of traditional timber.  Another problem with composites is that they are prone to mildew and discoloration.

Q:  Can you tell us more about what you refer to as specially milled softwood?

A:  The main problem with traditional softwood lumber is that it wears out quickly.  To address this, we’ve developed a specially milled softwood – we call it BMT decking.  We start with molded, #1 grade southern yellow pine, which is one of the best quality softwoods available.  We mill the surface for a smooth walking surface, router the edges to lessen wear on the vulnerable edges and put relief cuts in the bottom to eliminate the cupping effect.  This also eliminates any pooling of water on the deck surface, which we often see with standard cut lumber after a few years.  Finally, in addition to pressure treating the wood, we impregnate it with a moisture inhibitor that reduces expansion and contraction from moisture by about 30%.

Q:  What advice would you give to a marina owner looking for a timber deck option that provides the best value?

A:  I may sound biased but I truly believe the BMT decking is the best option for a marina wanting a timber system; it’s the best value.  Hardwood is great but costly.  With hardwood you often end up over compensating.  You purchase a material with a life span that’s greater than the life of your timber dock and you pay dearly for it.  Hardwood looks great when it’s first installed but over time the hardwood will gray like all timber.  If a marina is looking for an upgrade I’d suggest they put their money elsewhere, somewhere, where their tenants will truly notice and appreciate it.

With the changes made to the BMT decking to address the weaknesses of a traditional softwood deck, you’ll end up with a great product that will last.  If you have to replace a few boards in your high traffic areas after fifteen years, you’ll still end up ahead financially.

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