External Cladding

Why Timber Cladding?

Timber may be the ultimate sustainable building material, but there need to be more reasons to explain its popularity as an external skin for buildings throughout history. Today the main reasons are:

• It looks fantastic
• It has good thermal insulation
• It is one of the cheapest external wall options
• It requires minimal skill to install

The most important decision is what look you wish to achieve. A whole range of impressions can be given from rustic to urban sophistication. Boards can be as sawn, or fully machined to complex profiles. Whether the boards run horizontally or vertically, the most durable options tend to be the simplest. See drawing for some popular examples.

If cladding has no places where water is trapped, and adequate ventilation, it can have very long life. Boards should be fixed to battens at least 19mm thick, with gaps at the top and bottom of the wall for air to circulate. For vertical boards, it is advisable to use counter battens behind the horizontal battens to allow water to drain and air to flow. It is good practice to stop cladding 400mm or so above the ground, to prevent rain splash staining the timber and possibly causing decay.

Board width and thickness are partly dictated by the required appearance, and partly by practicality. Wider boards, and boards in less stable timbers, need to be thicker. We can advise on designs, but ultimately the choice is yours. If you can draw it we will cut it! For most jobs we fell timber specifically to meet the order, so we can choose log lengths to suit your requirements. Lengths of up to 6 metres are available.

We grow three species suitable for naturally durable cladding: oak, western red cedar and larch.

Nailing is satisfactory for softwoods. Trada would recommend screwing for oak, but nails are often used with good results. Oak should be pre-drilled. For oak and cedar, stainless steel is essential to prevent black staining. For overlapped boards my preferred fixing position is shown in sketch. If green boards are fixed with their heart side out, they pull tight when they try to curve as they dry. A 25mm overlap is usual for rectangular boards, reducing to as little as 10mm for shiplap.

Corner Details

With flush mounted boards corners can just consist of mitred boards, or one of the designs often used for overlapped boards (see sketch). Details round doors and windows vary greatly, but we can cut whatever matching trim you require. If using oak cladding, you may wish to use seasoned oak for the trim if movement is likely to be a problem.

Treatment & Maintenance

None required! All these timbers will weather to silvery grey with time. The time taken is dependent mainly on the amount of UV light that the boards receive, and to a lesser extent the amount of exposure to rain. A south facing wall may weather in one year, a north facing one three years.

More information?

Ring or email Nick Hoare, 01747 840643 or nick@stourhead.com .