Getting Timber Cladding Right
There’s more to specifying timber cladding than deciding on the wood used — the profile, size and finish all impact. Mike Cruickshank explains what to consider and how to get the installation right
There’s more to choosing timber cladding than deciding on what wood to use. Mike Cruickshank explains all — and provides his guide to getting installation right
Timber is the most sustainable construction material known to man, and it is also one of the most aesthetically pleasing. It’s no wonder that timber remains a popular cladding material in the UK. Architects are increasingly specifying timber cladding (sometimes referred to as weatherboarding or siding) for both traditional and contemporary projects. It is typically used as feature panels or to break up the mass of a façade, but it is also commonly used to clad entire façades. However, there’s a lot to consider: it’s not simply a case of choosing a timber. Ensuring it is fitted correctly and the right surface treatment is applied (unless, of course, you want the silver/ grey natural weathered look of untreated timber) are essential to ensuring your new cladding looks good and performs as it should. This will take a bit of time to fully research and decide upon, but it will be time well spent. The alternative is to rush, get it wrong and be faced with having to live with an unattractive finish for decades, or worse still considerable expense and inconvenience of having to replace it.
Common Timbers
There are a number of different series of timber which can be used for cladding. Each carries its own set of properties, pros and cons. Popular choices in the UK include: Redwood – This is the most cost-effective cladding available. If it is to be left untreated, its lifespan will be less than the alternatives below, but if regularly treated it will last for decades.* Larch – Very common and can be ‘ home grown’ or Siberian. Home grown has a lifespan of 30-50 years, while Siberian larch has a lifespan of 50-100 years. many Western as the red ultimate cedar in – Regarded timber clad- by ding with a lifespan of 50-100 years, and probably the most popular. European oak – Being a hardwood, it will have a lifespan of at least 50 years. Other options include sweet chestnut, whitewood and Douglas fir. But there is another alternative which is becoming a popular choice with self-builders for its low-maintenance properties, stability and durability — modified timber. Products such as Thermowood Accoya, Kebony, are typically Brimstone created and by different (usually patented) means which see non-durable woods transformed into durable, stable timbers. Some are thermally modified (heated at high temperature); others are treated by chemical processes. Accoya, for instance, is created by acetylation and results in a product which is dimensionally stable and has a lifespan of 70-100 years. Although typically more expensive than other options, modified timbers are certainly worth consideration. taking Whatever care timber of our you environment opt for, is a responsibility we all have, so purchasing timber certified by either – or ideally both – the FSC (Forest Stewardship Council) and PEFC (Programme for the endorsement of Forest Certification) schemes is a very good idea. These schemes guarantee that the trees harvested are replaced or allowed to regenerate naturally.
Finish Options
Cladding timbers can either be dressed (smooth) or off-sawn (rough) and can be left untreated to ‘weather’ which will result in a silver/grey finish. How quickly the cladding will ‘weather’ will be entirely dependent on weather patterns, situation, location and aspect. As a general rule, the more exposed to sun, wind and rain the cladding is, the quicker it will ‘weather’; six months would be fairly typical. One point to consider is that different elevations may weather at differing rates, depending on exposure and this isn’t desirable to all self-builders. Products such as SIOO:X, which accelerate and even out the weathering process, can be specified through some suppliers, such as Russwood, as a solution. You can buy cladding that has been treated wish and to these pretty products much any will colour typically you come with a guarantee ranging from two to 15 years. Alternatively, you can treat the cladding on site and there are many finishes available to you. If you use a paint, stain or an oil finish, you should always ensure it contains a UV filter (try Osmo).
Profiles, Size and Pattern
The is ular heavily finished profiles impacted shown appearance right), by the of profile the the cladding size, (pop- the width of board used and the pattern in which the boards are fixed (horizontally, vertically, diagonally, herringbone, for instance). Ask your cladding supplier if they have a showroom you can visit to view sample panels, provide photos of completed projects, or addresses of completed projects in your area that you can visit. If you have an image from a magazine of timber cladding you like the appearance of then furnish your supplier with a copy, as they should be able to advise you on the profile and size of cladding board used. Other than for soffits not exposed to direct rainfall, where a minimum 12mm thickness of cladding can be used, the thickness of cladding should be a minimum of 19mm.
Obtaining Quotes
You will need to have decided on the cladding, dimensions and profile, and the area required when obtaining quotes. Remember to add between 5-10% for wastage and on-site damage — the inconvenience and extra costs incurred in not ordering sufficient timber can be significant. You should also ask what the lead-in time is for supply- ing the cladding to site, as this can vary from as little as a few days to weeks or sometimes over a month depending on stock levels and/or holidays. You should always obtain a minimum of two quotes and take care to are compare ‘ like for the like’. quotes I also to think ensure it is good they practice to get the supplier to also supply the fixings as part of their package as they are the experts and know what ding fixings you are are best purchasing. for the particular clad-