Looking after your glulam; top tips for protecting glulam during your project



Working with wood can be a wonderful way to bring a project to life, and glulam is a particularly cost efficient and sustainable way to add a natural and warm aesthetic to your build, amongst other things. 

However, as a natural material, it is important it is looked after at every stage of the process from drying out the wood to glulam manufacture, storing on site and finishing off, so your result is the best it can be and long-lasting. 

When your glulam is manufactured by us at the factory, we do everything we’re able to create and check you get the best quality glulam. Once the glulam leaves the factory and is on site, we’re not as close to the process, so have put together a few tips to help you look after it. 

protecting glulam 1280

Do you need to protect different species of glulam differently?

The short answer is no, not really.

You may want to consider however what the visual expectation is from the project. For example, a large commercial building made from spruce will have a different expectation on the finish to a house extension made from Oak glulam. The level of protection you need will differ more in line with the aesthetic quality level rather than the species used.

How can I protect glulam during transportation?

Our glulam comes with a black plastic wrap on it, which provides a short-term protection during transport and installation, but we recommend it is taken off immediately after install. This wrap does keep water out temporarily, but in the longer term would let water in and can keep the water against the surface of the timber, so it’s better taking it off and leaving the timber exposed once it has been transported.

How to protect glulam on site

Protecting your glulam on site can be a difficult thing to get right. The first point to note is the glue which is used to glue the individual pieces of wood together will generally be water resistant, so the glue is not going to degrade in rain. This is good to know – if the beams get wet, they won’t immediately start to fall apart!

Any damage over a few weeks or even months of exposure is most likely to be aesthetic. It doesn’t necessarily mean it’s only minor, but usually it can be repaired by sanding and refinishing.

Joints can be problematic, especially if the orientation of a slot means water can pool in it. Design of joints to avoid this, or covering the top of the joints to prevent water getting in can help.

Metal filings/ grinding on site should be mentioned as very minute traces of iron on the surface of the timber go black very quickly when wet, (it is often mistaken for mould) so metalwork / grinding near the glulam should be avoided. Also fixings of other materials into the glulam should have some protection against rust to be stainless.

What happens if Glulam beams get wet?

If beams get too wet, they’ll expand. This can cause previously snug joints to open up or it can cause cracking when they dry out again (see more about cracks in glulam here).

To help with this, wrapping of the structure is an option but it’s got to be done as a second phase job and done well using a loosely tied breathable wrapping.  In our experience we’ve not seen a job which had been wrapped and left for a long period of time which hasn’t had some problems. If you have to do this needs to be carefully maintained and checked to provide protection for more than say four weeks.

How can I protect glulam from the elements once the initial structure is erected?

One way of protecting the glulam so you don’t have to worry about it being outside for a while is by using a heavier, or more coats of, varnish.

There are varying levels of varnish we provide – it is one of those ‘how long is a piece of string’ questions, but our standard varnish finish will cover you for about a week if left unprotected to the elements. If you know ahead of time your glulam may be exposed for longer and you want to make sure, we can do two coats.

There is a heavy-duty oil-based varnish you can use which can give you a good few months’ worth of protection, and then external stains are good for a few years.

Better options if your frame is going to be exposed for a period of time would be to quickly board and apply a membrane to the roof, or even erect a scaffold roof over the frame.

The main thing to be wary of is water getting into the joints of your structure – if the structure is not designed to be out in the wet, you’ll need to ensure you keep everything covered up to avoid joints beginning to rust.

The comforting thing to take from this, from a structural soundness perspective, is we’ve never seen a job (touch wood!) structurally damaged by being exposed to weather on site for too long while it’s been installed. 

It is very unlikely your glulam will have any sort of exposure damage during installation which causes a structural worry, it’s most likely to be aesthetic – with the right application of some of the solutions we’ve mentioned, you can avoid most issues.

If there is anything worrying you about protecting your timber, or you’d like to talk it through with one of the team do give us a call and we’ll be happy to help.