Thermowood Shiplap Cladding

Thermowood Shiplap Cladding

Thermowood Shiplap cladding is a great material for external cladding, it is highly durable and is very stable due to the treatment that the timber has undertaken. Thermowood is a Scandinavian Pine which has been heat treated to remove as much moisture from the wood as possible. This makes the timber more stable, so it doesn’t warp as much as it would and has the added bonus of removing any resin which helps to prevent the wood rotting.

Thermowood is supplied as Sawfalling, so you can expect to see a large knot content. Most of these will be live, sound knots, however there is the chance for the supply to contain some dead knots as well. So, we recommend ordering an extra 10% so these knots can be cut around.

Shiplap cladding is designed to be fit horizontally on the wall and has a channel machined into the wood to allow water to run off. There are two available profiles:

• IWC6
• IWC7

Which are slightly different from each other. IWC6 is designed with an overlap whereas the IWC7 is more of a T&G hybrid, allowing for secret and face fixing.

Thanks to the process it has been through, Thermowood shiplap cladding doesn’t need painting or oiling to seal it, however if you would like top preserve the colour or stain it with a paint, the wood will take the finish well. We recommend wood finishes direct for oils and paints on timber products.

Siberian Larch Alternative

With the current state of Siberian Larch supply being put on hold, we think that Thermowood is a viable alternative. Not only is it cost effective but it offers high durability to compete with the British timbers supplied.

Our Thermowood is available as PEFC certified because it is sourced from sustainable sources.

Fitting Guidance

Our fitting guidelines are designed to give you a starting point on how to fit your shiplap cladding and we recommend that you consult an expert fitter to advise on your actual scenario.

Be sure to read our treatment guidance as treatment needs to be applied prior to fixing your cladding

Breathable Membrane

Consult a fitter to determine if your scenario would require the fitting of a breathable membrane between your wall and the cladding. This membrane stops rain getting to the wall, but allows moisture to escape, helping to prevent internal condensation and mould that can come with it.

Treated Softwood Battens

Treated softwood battens (available from our cladding accessories pages) are most commonly used to fix to the wall (or on top of the breathable membrane) to then fix your cladding to. Shiplap cladding is to be fixed horizontally only, so your battens need to be placed vertically, at around every 600mm (60cm).

Fixing the Cladding

** Whether you use nails or screws, it's important that they are stainless steel, or silicone bronze ARS, so that the natural tanins in the timber will not corrode them. Never use iron nails for fixing timber.

The timber is designed to only be fitted horizontally with the start of the running lip across the width of the timber at the top. To stop your wood from splitting it’s best to pre-drill any holes and then hold the boards with the head of the screw.

You can also use nails, preferably ring-shanked for extra grip, and again stainless steel so they don't corrode. For lower-density species like cedar, consider using nails with larger heads so the cladding doesn't pull through.

As already stated, these are just ideas to get you thinking about installation and you should consult a professional installer before fitting your cladding as every scenario is different.

All our claddings are provided untreated. Fresh sawn timber claddings are best left untreated and to go silver grey. There are a wide range of optional treatments available for different species of timber and we recommend talking to the excellent team at www.wood-finishes-direct.com, who know the most up-to-date information on all the newest treatment products.