How do different glulam species, adhesives and surface treatments behave when they’re exposed to real conditions?
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Most of our time at Buckland is spent engineering, designing and manufacturing glulam, CLT and even plywood for projects. However, behind the scenes, we’ve been carrying out a long‑term outdoor timber durability trial.
The aim has been to understand how different glulam species, adhesives and surface treatments behave when they’re exposed to real weather, real moisture and real conditions.
Read on. You’ll come away with new technical understanding, but more importantly, you’ll have an answer to this question: How can I be sure I’m choosing the right timber, finish, design and build?
Why we run our own timber tests
The question above comes down to your confidence and peace of mind. In short, Buckland Timber chooses to run its own in-house timber tests to give you that confidence in your project from start to finish.
As timber is often used in external structures, it’s open to variable factors like rain and heat, so we want complete control over all the advice we give you. For us, the best way to do that is to test things ourselves rather than rely solely on laboratory data or assumptions. The good news is, we’ve got the expertise to do so, which we know sets us apart in the industry.
What timber and products we’ve been testing
We’re looking at different timber species and how glulam made from Sweet Chestnut, UK Larch, European Larch, Oak, Spruce and Accoya performs over time when exposed to long‑term moisture.
Once timber becomes saturated, it creates more favourable conditions for fungal growth, which can lead to brown or white rot. In severe cases, these issues can compromise a building structurally – not something we’ll allow.
The aim of this test is more on the effectiveness of different finishes and the stability of the different species. This is dry glulam elements designed for use in service class 1 & 2. We are leaving them fully exposed to see what happens and really test the finishes and glue bonds in real-life external conditions.
(Do have a look at our Timber Species page if you want to brush up on the characteristics and best uses of these.)
We’re also comparing two adhesive types, namely Melamine Urea Formaldehyde (MUF) and Phenol Resorcinol Resin (PRR). Alongside the adhesives, we’re comparing SiOO:X surface treatment on two faces of each sample, leaving the other two untreated for direct comparison. Again, your bonus ‘homework’ might be to look at our Glulam Stains and Finishes Guide for a quick recap.
How we’ve set up the trial
We’ve set up the samples in Buckland Forest at a location where humidity and moisture exposure are higher than in typical residential or commercial settings. The end grain is protected with stainless steel caps to protect the end grain from direct exposure to moisture helping us focus on how the timber, adhesives and surface treatments behave rather than how quickly water enters through the ends.
It’s a simple setup, but deliberately real‑world. It’s the kind of environment where external glulam has to prove itself, and we can get a clear comparison between the timber species, adhesives and treatment.
Why this kind of testing is rare
The internal testing we do at Buckland Timber is important, but it’s good news for you and our customers. There are three clear reasons why this sets us apart:
- Our love of timber and care for the timber construction industry means that, as engineers, we genuinely want to produce the best timber and push the sector forward.
- Our decades in the timber industry developing glulam projects mean we have the expertise to take the lead.
- The quality of information we get from testing internally is key. There are loads of laboratory studies on timber durability, but very few real‑world trials comparing glulam species, adhesives and treatments in the UK environment. Large sample testing with glulam is expensive, which means most manufacturers rely on published data rather than running their own long‑term trials. We prefer to understand things first‑hand.
Pushing for excellence is ingrained in us. It’s the same reason we carry out our own timber fire tests, which you can read about in our Glulam and Fire Safety blog.
What we’ll learn and how it will help our customers
Within the first year, we’ll start to see visual differences, especially between treated and untreated faces. The most valuable insights will come over several years as the samples continue to weather naturally.
Based on what’s already known, we’d expect spruce to show signs of degradation first, while Accoya should perform best, with larch, sweet chestnut and oak somewhere in between. One of the most interesting comparisons will be MUF versus PFR adhesives, as we want to see whether adhesive choice makes a noticeable difference in a high‑moisture environment.
How the information will guide your projects
You can think about this on two levels. For your projects, the results will help us give even clearer, more confident advice on species selection, surface treatments and adhesive choices. The testing will help us make better glulam and help you make better decisions.
Thinking bigger picture, our testing continues to contribute to the wider understanding of engineered timber durability. This knowledge is exactly what the industry needs as external timber structures become more common. Even if you don’t work with us, others in the timber industry will be better because of this work.
Next steps for your work with timber
Buckland Timber is pleased to be at the forefront of gathering all this information, first-hand. It puts us in a great position to work with you individually on your timber project, but also to be able to do so with an industry-wide perspective. It puts you in a great position, knowing we’re answering the same questions you’re asking.
If you have any more questions, or if you fancy a trip to see the testing in action, get in touch. We’d love to hear from you