British Larch Tongue and Groove Cladding

There are five profiles of British Larch Tongue and Groove profiles we supply which are:

• IWC1 - 19mm x 145mm overall, with a 135mm face - For horizontal or vertical fitting
• IWC2 - 19mm x 95mm overall, with an 88mm face - For horizontal or vertical fitting
• IWC3 - 19mm x 142mm overall, with a 125mm face - For horizontal or vertical fitting
• IWC4 - 19mm x 145mm overall, with a 125mm face - For horizontal or vertical fitting
• IWC5 - 19mm x 145mm overall, with a 125mm face - For vertical fitting only

Our tongue and groove cladding is more versatile than the other profiles of cladding we supply because the majority of them can be fitted horizontally or vertically. This means that you get the right look for your project. Only IWC5 must be fitted vertically.

We supply British Larch as Fresh Sawn Merchantable grade. Larch is a knotty timber making it full of character. The colours of British Larch vary from a pale reddish-brown to Brick red. If you would like to keep the colour of the wood then you can treat your cladding with a UV protection oil so that it doesn’t weather to a silvery grey.

British Larch is a great timber which is great for outdoor use because it is durable and resistant to rot. British timbers are becoming more and more popular and our British Larch is a really good British softwood which is priced competitively and gives a characterful, traditional look to your cladding.

The British Larch Tongue and Groove Cladding we supply is usually provided in lengths of 3m and longer. We can provide exact lengths if you need them however we do ask that you call us (on 01889 597281) or talk to us on our online before ordering so that we can check with the supplier. If we confirm we can provide the lengths you need, please enter them into the “Special Instructions” box on the shopping basket page.

Treatments

Be sure to read through our treatment information by clicking on "Treatment Guidance" above. It talks about sealing, preserving and protecting the timber from the sun's UV rays. Here are quick links to the products we recommend:

• Wood Preserver Basecoat - Barrettine Premier Universal Preserver
• UV Protection to Delay Weathering

Fitting Guidance

These fitting guidelines are only a rough idea on how to fix your tongue and groove cladding. We do recommend you employ a professional who has experience fitting tongue and groove cladding.

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. If you are fixing your cladding horizontally, your battens need to be placed vertically, at around every 600mm (60cm), and vice versa.

Fixing

** 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.

To help stop the wood from splitting we recommend pre-drilling the timber and then holding it with the screw or nail head when you fit the board to the batten. Look to leave a 3mm gap between the boards, rather than butting them up tight like flooring, to account for any moisture movement and make sure that the tongue is facing upwards otherwise moisture will start gathering in the groove of the profile.

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.

You can fit IWC 1,2,3 and 4 vertically or horizontally depending on the look you want from your timber. Whilst technically you can fit IWC5 horizontally, water can sit in the square channel, which is not recommended.

With each new row of cladding you add, it's preferred that you stagger the joins between each board so you don't create a visible seam.

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.

Treating Timber Cladding

All of our timber cladding is provided untreated.

For best results, cladding should be treated before it is installed to ensure application of the treatment on all sides and ends of the boards.

We recommend Wood Finishes Direct for all of your treatments. We have found them to be well priced and their telephone support and advice is second to none. We highly recommend giving them a call.

The following information is from Wood Finishes Direct in relation to treating timber cladding.

When it comes to treating your timber cladding, there are three areas of protection to consider.

1. Sealing against moisture movement - Sealants are used to help prevent moisture entering the wood causing it to expand. Kiln dried timber like European Oak will definitely need to be sealed, and for other timbers it is highly recommended.
2. Wood Preserver - Helps to prevent rot and protects the wood from insect infestation and mould.
3. UV Protection - The ultraviolet rays of the sun slowly bleach external timbers. UV protection oil helps to keep the natural colour of your timber for longer and prevent it from turning silvery grey so quickly. Some people like their timber to weather and prefer the silvery grey look so it’s completely down to you.

The following links will take you straight to the products on Wood Finishes Direct's website:

Product to Seal and Preserve

To address Sealing and Preserving, they recommend applying one or two coats of "Wood Preserver Basecoat - Barrettine Premier Universal Preserver" before installation to seal against moisture movement and protect it from mould and insects.

Product to Protect from UV Rays

Then to optionally delay weathering, two coats of OSMO UV Protection Oil. There are different colours of OSMO UV Protection Oil available, with names like 'Cedar' and 'Oak', but these colours are to make other timber look like the stated species. We recommend the 420 clear version which interferes the least with the natural colour of your timber.