What is Composite Cork Decking & how do we use it?

Introduction

Composite Cork is a natural mixture of cork and rubber which can be used for decking on boats. It has a number of benefits, one of which is that it has excellent eco-credentials when compared to less sustainable plastics and teak hardwoods. Combining the cork and rubber into a single decking solution gives it unique properties which have a number of benefits over other materials and makes it an increasingly interesting material for boat owners to consider when thinking about their boat decks.

I remember at school experimenting with different materials and seeing for myself how cork remained cool when exposed to heat when compared to a wide range of other materials. It is an amazing insulator. This ability to insulate is significant when considering cork for decking as it will allow you to walk barefoot on the deck in hot weather and will keep the temperature cooler below decks. As an insulator it also reduces damaging condensation below decks and also the noise travelling through the boat. These are properties that will benefit all boat owners but will be particularly attractive to owners of large steel motor boats. Boat owners with cork decks have also noted significant reductions in their heating use in the winter periods. Combined with the excellent durability that cork decks provide, there are significant benefits to using cork as a decking materials.

Of course, there are some challenges when using cork for decking. One of these is that cork usually comes in sheet form and is brittle and inflexible. As a natural product it will also weather quickly and turn a grey colour that is less emotionally appealing to boatowners. So how do we mitigate these problems and produce a cork decking product which can overcome these issues?

Firstly, to overcome the brittleness and inflexibility we mix cork granules with rubber and use a binding agent. This changes the cork from a typical 6ft x 4ft sheet to a roll product 13m x 1 metre long and 5mm thick. This is perfect for a large wooden or steel leisure boat to cut to shape and bond to the deck substrate, typically using an ms polymer glue widely used in marine applications. The rubber within this composite material does give off a certain smell that takes time to wear off. This is not an issue for external decks but using it below decks without much ventilation may cause people to have second thoughts. To mitigate this, the product has been continually developed to increase the cork content as far as possible, with the use of binding agents within the composite allowing the product to remain as flexible as possible.


Secondly, to overcome the changes in colour which can be experienced with cork decks, we oil the deck prior to fixing onto the boat and owners continue to do so as part of their regular beginning and end of season routine. Although cork composite requires more maintenance than a PVC deck, it is easier than maintaining a teak deck and has a higher proportion of natural ingredients than PVC decks.

Making Cork Composite Deck Panels and Decks

The cork rolls can be grooved normally either using a CNC machine or a hand router. Once grooved they are filled by masking up either side of the groove by spreading an ms polymer sealant/adhesive into the channels. This gives a traditional marine deck look, with the regular oiling of the deck in a teak stain leading to a good teak deck effect.

Traditionally, large production deck builders lay huge teak deck panels onto GRP cloth ready to fit onto large production boats. The solid teak deck panels may be cumbersome to transport but they are broken down into manageable parts for reassembly onboard the boat. This is more difficult with cork composite decks with transport more likely to cause damage. For this reason, composite cork lends itself more to DIY/retrofit applications by local fitters on larger boats. A skilled fitter or DIY tradesman will easily cut the cork to shape straight off the roll with a stanley knife, joining the composite cork at the edge with a bead of adhesive and hiding the join under the deck caulk. 2mm grooves can be cut to the deck pattern, with masking and filling using the sealant/adhesive achieving the desired traditional deck look.

Small panels can be easily cut on a CNC machine and panels sitting on a 2m x 1m CNC machine are reasonably transportable. Larger panels can be problematic. Cockpit seats on sailboats are consequently targeted as good potential applications for composite cork. Beautiful Marine Floors will supply “50mm ready grooved and oiled” composite cork material off the roll which can be turned into unmargined deck panels by caulking the grooves as explained above.

Costs

Comparing costs is not totally straightforward, for the reasons outlined below.

Natural teak decks will be the most expensive to use, with the price dependent on the thickness and quality of the teak. PVC synthetic teak panels are usually around £300 per sq metre and can be fabricated into large deck panels. Using cork composite for larger boats costs around £50 per sq metre, but it should be remembered that these relatively low costs will be augmented by the fact that considerably more fitting work is required ‘on-site’ compared to that required for fitting ready-made PVC synthetic teak panels.

Laying the plain cork composite is a similar amount of work to a PVC synthetic deck but it does not end there. The fitter will need to router the grooves, mask and fill the channels which is labour intensive work. However, it does mean that a competent DIY tradesman can make considerable savings should he choose to fit a composite cork deck himself.

Smaller and more intricate composite cork deck panels from templates often end up costing similar sums to PVC synthetic teak deck panels. The templates need to be converted into CAD drawings and then CNC machined so the processes are more involved before filling with deck caulking. However, a good DIY person could simply buy “ready grooved” material, cut to shape and fill making significant cost savings.

Conclusions

Composite cork is a durable, non-slip deck covering with excellent eco-credentials that only requires a little annual maintenance to ensure it keeps its teak effect appearance. Its unique properties should appeal to many. For larger decks professional fitters should be able to fabricate the decks themselves on behalf of their customers with simple tooling. For DIY it has the attraction of major cost savings compared to other decking materials that require panel fabrication. The material has some limitations for use in larger panel fabrication in particular transportation without damage.