All You Need to Know About Using Wood for Your Home’s Exterior

Thinking about renovating the exterior of your home with acetylated wood? ACCSYS Technologies gives tips and advice for using wood in your home’s exterior and explains acetylated wood

What tips can you give for cleaning exterior wood?

If the wood is painted or stained then you should follow the recommendations of the coating manufacturer. If the wood is uncoated then usually cleaning with a stiff brush and a dilute vinegar solution (one cup in a bucket of water) will suffice. Washing with high pressure jets should be avoided since this damages the surface of the wood. For stubborn stains, wood cleaners based on oxalic acid are suitable.

See also: Draught Proof Doors and Windows

What factors should I consider when renovating the exterior of my home with wood?

The challenge with external timber is to ensure that the original look that you have chosen is maintained over time and this depends on a number of factors.

Design: Ensure that water is not allowed to collect on horizontal surfaces, even if the wood is coated. Allow at least 25mm of free air flow in the vertical direction behind timber cladding and raise timber cladding at least 200mm above ground level out of the splash zone. If your cladding is to be painted you will get longer coating life if the cladding profile has a radius of at least 3mm on all exposed edges.

Stability of the timber: Some timbers move a great deal more than others in response to changes in humidity. Such movement not only manifests itself as an increased risk of cupped or twisted boards or jamming doors but will also have a significant effect on the maintenance interval of any paints applied to the timber.

Fixtures and fittings: Use good quality fixtures and fittings, made for example from stainless steel or solid brass. This is particularly important in exposed or coastal areas. Poor quality fittings will corrode more quickly, detracting from both performance and aesthetics.

Durability (rot resistance) of the timber: Timbers vary greatly in their natural durability which is classified on a scale of 1-5 with 1 being the best and 5 the worst. The greater the durability of the timber that you choose the longer it will last. With the most durable timbers you can expect them to last at least 60 years above ground.

Coatings: All timbers go grey if left outside uncoated and exposed to UV light. The greying process is uneven and in shaded aspects will be exacerbated by the development of surface moulds and algae. Some people accept this as natural weathering of wood but if you want to maintain a specific colour to wood then you need to paint or stain it. The choice of the type of coating that is used will have a significant impact on the amount of maintenance that is required. Stains will generally be required to be maintained every 1-3 years, whereas coatings that form a film on the surface of the wood (that can still allow the wood grain to be visible is translucent versions are used) can be expected to last for at least 10 years when applied to a stable timber that has been well designed and installed. Avoid very light translucent colours. They may look great for two or three years but will deteriorate more rapidly in appearance than darker colours that offer better protection against the deleterious effects of UV light.

Building regulations: Depending on the renovation work that you intend to carry out there may be a requirement for planning permission. Of particular note is if you intend to use timber very close to an adjacent property there is likely to be a requirement for the timber to be treated to meet fire regulations.

How can I choose the best type of wood for my home?

Ask the experts, for example your local joinery companies or a specialist timber cladding supplier. They will generally be able to offer you a choice of different timbers and should be able to explain the relative differences in terms of performance and sustainability. A good source of independent information is TRADA, the leading authority on wood. In general terms you get what you pay for in terms of performance with timber.

See also: Heritage Homes

How should I prepare my home for wood cladding?

The most important thing is not to fix wooden cladding directly onto an existing wall but instead to allow for ventilation behind the boards by means of attaching wooden battens to the wall first and then attaching the cladding to the battens. Your cladding supplier should be able to give you details of what type of battens to use and what spacing you need etc.

What is acetylated wood and how does it differ to other types of wood?

Acetylated wood is a sustainably grown timber that has been modified by a process akin to pickling. Acetylation converts molecules in wood that cause problems by drawing in moisture from the atmosphere into other naturally-occurring molecules that don’t. The consequence is that water finds it very difficult to get into the cell walls of the wood, resulting in a very stable, class 1 durability, yet non-toxic timber. Acetylated wood offers the best combination of durability and stability of any timber and at the same time is produced in a sustainable manner.

I live in a period home, is it possible to use acetylated wood whilst keeping the aesthetic integrity of the exterior architecture?

Certainly. Acetylated wood is wood, as opposed to a composite product containing plastics.

What are the current exterior architectural wood trends?

Painted timber cladding is becoming more popular in order to avoid uneven greying and surface moulds and there has been increased interest in charred timber cladding in recent years. Decking installations are becoming more and more sophisticated in terms of multi levels and features such as glass balustrades. Timber windows and doors are becoming increasingly more thermally efficient and there is a definite trend towards increased use of bi-folding doors and windows to break down barriers between home and garden.

What is the best stain to use on acetylated wood on my deck?

If you are happy with a natural grey deck over time that will require cleaning once or twice a year with a brush then there is no need to use any stain. However, if you want to maintain a colour other than grey to your deck you can use a penetrating oil stain but you need to be prepared to re-apply once a year in order to keep it looking at its best. Avoid the use of film-forming or lacquer-containing products such as Danish oil on decks.

See also: Working with Nature

Is acetylated wood flammable and how does it fare against other types of wood?

Yes, like all wood acetylated wood is flammable.

Is acetylated wood recyclable?

Yes, since there is nothing in acetylated wood that wasn’t in the original wood (just more of some naturally-occurring chemicals and less of others) it can be recycled in the same way as untreated wood. It doesn’t need to be disposed of as landfill.  In most cases Accoya is likely to still be intact when the product from which it was made has completed its service life, in which case the Accoya can either be re-worked to make another product. Alternatively it can be recycled as wood chips or burned to produce energy.

Our thanks to Accsys Technologies PLC and Medite Europe DAC for their assistance in this article. Accsys Technologies PLC is a chemical technology group focused on the production and licensing of acetylated wood with products such as Accoya® and Medite Europe DAC manufacture MEDITE® TRICOYA® EXTREME under license to Accsys.

Need more information on acetylated wood and renovating your wood exteriors? Read more on Celebrity Angels about using wood for your home’s exterior.

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