Glulam Timber Stains and Finishes: A guide

If you’re considering using glulam timber for your project, not only will you be thinking about which timber species to choose, you’ll need to think about what you want the finished product to look like.

Stains and finishes enhance the look of your glulam but also protect it from the elements and extend its lifespan.

In this guide, we’ll explore the different finishes available for glulam, the cost and how to look after it.

What colour finish would you like?

The finished colours of glulam vary depending on the timber species you choose. Different timbers will weather differently and all species of timber will change colour when exposed to sunlight.

It very much is up to personal choice. A completely clear finish which preserves the natural colour of the timber as it leaves the factory will still change subtly over time. Any finishes that stop this process from happening by blocking UV light will have some form of pigment and so won’t represent the natural colour of the timber. Therefore you can choose the style of finish you would like to ultimately see – if you want it to be ‘natural’ and remain looking that way, you probably need to choose a pigmented stain.

There is a huge range of colours and types of finishes to choose from. Some will be translucent and still enable you to see the grain and the natural timber undernath, some will be opaque. An example being white stains or oils provided by Osmo and Remmers are available with differing levels of white pigment depending on your preference.

Which finishes should be used for internal glulam?

Our standard internal varnish is a water-based clear matt varnish made by Flag Varnish. It gives a very natural look and can be difficult to distinguish from unvarnished timber. We describe it as a temporary protective varnish, as it is mainly used during transport and installation to keep dirt and water out.

Buckland provide one coat of Flag varnish as our standard, but we can also apply two coats for better protection. For a more durable internal finish, we recommend two coats of Sadolin Extra Durable Clearcoat, which has more of a glossy yellow look, but has a good track record on durability.

If the Sadolin is too warm a look for you, we also offer Remmers stains in clear, white, and other colours for internal use.

We’re happy to trial finishes for customers based on their specific requirements, just ask.

(L-R) Stone pine/Larch, Clear UV, Mahogany, Teak, Nutwood, Plain Sample (no treatment)

(L-R) Flag, Light Oak, Palisander, Flag, Clear UV, Plain Sample

Which finishes should be used for external glulam?

Glulam used for outside structures requires a UV-protective finish.

Our preferred external finish specification on larch or Douglas fir glulam is SiOO:X. This silicon-based preservative treatment has a brown colour and can be very uneven for the first few weeks after application. However, when exposed to the weather it will change colour for months or years, eventually turning a natural silver-grey colour. Sioo has a maintenance cycle of up to 10 years, depending on exposure.

Alternatively, two coats of Sadolin varnish can also be used externally, but this will need maintenance within 4-5 years.

Remmers Aqua MSL 45 stains are our most common external treatment. Available in varying colours these also have a maintenance cycle of around 4-5 years.

Again, as with internal finishes, we’re happy to look into other finishes for you if you have particular requirements for your project.

How much do glulam stains and finishes cost?

The cost of stains and finishes can vary. You’re most likely to be looking at between £8 – 30 per square metre depending on the type and difficulty of application. It is tricky to completely finish beams in the factory without having to do any touching up or snagging once it is installed. Not all the glulam we make requires a varnish as customers may want to apply it themselves.

If we offer a varnish, our Flag varnish is our standard option and one of the most budget-friendly. Costs for Remmers stains, Sadolin varnish, and Sioo treatment varies, but we can advise you when you make your enquiries so you know what to expect and allow for.

How long should glulam stains and finishes last?

As we’ve already mentioned, it very much depends on where the glulam is installed and the level of wear and tear it will get.

If your glulam is indoors, the maintenance is no different to other areas like walls and ceilings. If it is in a high-traffic area exposed to harsh sunlight for example it will need attention more quickly.

Externally it varies depending on the treatment chosen, and the exposure to the elements. With good maintenance you should be able to achieve a 30-50 year design life externally, internally if the structure is kept dry and is looked after there is no reason not to expect 100 year + lifespan.  This does depend on care and maintenance so we suggest you inspect it yearly and retreat if required.

What about fire retardant finishes?

The last thing to consider around stain or finish choice is there a specific purpose it is going to serve, such as requiring a fire retardant finish. In our experience these are usually applied on site after installation has taken place, and while we are not experts in this area we are happy to help advise on some of the products available and compatibility with other finishes – this is a topic that could have a whole blog of its own!