Where did you get that oak frame?

Posted by Derek Mason

4th June 2024

Picture credit: Avel Chuklanov on Unsplash

We know that when we buy groceries, air miles are an important consideration, but why are we not prioritising this when it comes to building materials? The UK is the third largest net importer of timber after China and the USA. Approximately 80% of the construction industry’s timber needs are met using imports.

However, even though we import much of our timber, we’re exporting timber too. The UK’s exports of wood products were estimated at £1.7 billion in value in 2023, according to Forest Research.

Knowing what we do about the need to reduce our carbon footprint, it would make sense to use more of our native timber in construction. Not only would this reduce the miles travelled by the timber we use, but carbon is stored in timber, meaning it plays a role in hitting our net zero targets. Yes, those are the targets that we all know we’re not likely to hit by 2050, but that we should at least keep working towards.

So what’s stopping us from using more of our homegrown forests, and how do we go about sourcing UK timber for our projects?

Using more of the UK’s softwood timber

According to data from 2020 and 2022, only around 63-67% of the UK’s net annual increment is felled. That’s the volume of timber available to harvest each year.

This means that there’s plenty of timber available, if we can increase local demand for our native wood. On top of that, government targets to boost tree planting mean there should be additional timber available in the future.

So what stops us from using our own timber? To some extent this is due to strength requirements. Coniferous trees in colder climates grow more slowly, maturing in 60 years or more, compared with 40 years for a spruce in the UK. Our softwood conifers tend to make good structural timber at strength class C16. This is suitable for general construction applications such as structural timber frames, floor joists, rafters, roof cut timbers and internal partitions.

But conifers from the Nordic countries make stronger C24 timber, which is better for longer-span floor joists or trussed rafters. To some extent, what we need to do is avoid over-specifying. Using the right strength grade for the right application will mean we can use more of our homegrown timber. This will also result in cost savings, as the wholesale price of C16 timber is usually around ten percent less than C24.

Hardwood and the problem with specifying oak

Only 5% of all timber consumed in the UK is sawn hardwood, but 97% of it comes from overseas. And 57% of all hardwood specifications in this country are for oak.

Oak frames are popular, despite the cost, but we may want to look at alternatives, as relying on one species is unsustainable. A Grown in Britain Woodstock report recommends an increased focus on UK grown hardwood, with alternatives to oak being specified wherever possible.

Chipboard and other sheet materials

Happily – when it comes to reducing the miles travelled by our materials – a lot of the chipboard, OSB and MDF used in our buildings is manufactured here. One exception is plywood, which is usually imported, so specifying OSB is a better alternative. It’s made here, and it also has 20% of the embodied carbon of plywood. There are imports around though, so it’s important to check where your OSB is sourced.

As well as being a great option for more sustainable projects, sourcing UK timber is important when it comes to meeting the requirements for BREEAM, SKA and LEED. And as more of our clients request sustainable building materials, it will hopefully become easier to source them. Much like consumers might look for the Red Tractor logo on their food, schemes like the Grown in Britain Certification will hopefully become more widely known.

I suspect progress will not be fast in this area, but we can all play our part. When we’re working with clients who care about sustainability, we’re in a good position to steer them towards our homegrown timber rather than the unsustainable imports. What do you think about this? Are we going to see more of a trend for building with homegrown wood, or will imports continue at the same rate?

In the meantime, if you need assistance with the structural elements of an upcoming project, please do get in touch.

Looking for help with your project?

It is our technical prowess for modern, clean design and astute commercial acumen that results in saving clients’ time and money.

Tell us about your project
RBA RBA The Instituition of Structural Enginners Trada member ACE
ISO-9001-UKAS ISO-14001-UKAS ISO-45001-UKAS