Curved glulam beams: Straightening out misconceptions about costs
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We recently shared, as an April Fool’s joke, an AI-generated image of a rather complex, large, curved glulam structure. It led to a lot of entertaining conversations, but we also realised that while we make a huge amount of curvy glulam, we hadn’t shared much about it of late, so we decided to rectify that.
There is a common feeling that curved glulam beams are excessively expensive, and this can lead to the option not being considered at early stages of design. This is sometimes right and sometimes wrong!
It makes sense – a curve equals skill and complexity, and complexity equals cost. But as with many things, the devil is in the detail…
Even though all curves look impressive and rely on manufacturing expertise, the real clincher on cost is their tightness or radius. Shallow curves can be surprisingly affordable.
So, let’s break down how glulam curves are made, why radius matters so much, and what that means for your project.
How curved glulam is made
Curved glulam is made by laminating thinner-than-normal planks (lamellae) and using clamp frames to bend the timber precisely around the required radius.
There’s no steam bending, no soaking, no heat, but by the end of the clamping process, the glulam is naturally and precisely curved. It’s something we specialise in at Buckland.
The curve decides the timber thickness
You’ll hear the words curve and radius used interchangeably. Put simply, a bigger radius means a bigger circle and a shallower curve. Based on a simple rule of thumb, it’s this radius that decides the thickness of the planks we use:
Plank thickness ≈ radius ÷ 200
This means the tighter the curve, the thinner the planks.
An 8 metre radius uses planks around 40mm thick, while a 1 metre radius is trickier and needs planks around 5mm thick. Of course, we love to work with this type of complex, high-specification project, but at this point you’ll need to closely match your design and budget. Let’s explain why.
Tighter curves mean tighter margins
Anything tighter than about 8 metres means we must either plane the planks or cut them down the middle to make them thinner. Naturally, this adds time, labour and waste.
Most of the cost in glulam manufacturing comes from activity per metre of plank, including sawing, planing, finger jointing and glue lines. If you halve the plank thickness, you effectively double the metres of plank needed for the same beam depth, and every lamination adds more planing and more glue lines.
Its also the case that we would often need to use stock timber as the lead time would not be available to have planks sawn and dried to the specific thickness required, of the quantity needed might not be cost effective.
And so, it follows, tighter curves mean tighter margins.
Let’s think about making a 2 metre radius in spruce. The process would include:
- starting with 45mm spruce planks
- finger jointing them to length
- cutting them down the middle to ~20mm
- plane them down to around 10mm
The work per metre is big, and by the time you’ve cut, planed and re planed, the waste mounts up quickly.
Curved glulam in the clamps for a War Memorial Project
Why shallow curves remain cost-effective
Shallow curves are cost‑effective because we can still use standard stock planks (45–50mm spruce, 38mm larch, 25mm oak) with minimal extra processing. It goes back to that rule of thumb and finding the numbers that work.
People automatically think a curved beam is going to be way out of budget, but shallow curves really aren’t. We don’t want you ruling yourself out of the perfect curved design when it’s more in reach than you think!
Finding your design and cost sweet spot
While Buckland Timber has the expertise and experience to match the most complex briefs, we can also help you find the sweet spot where design and costs work. With the right planning, you can have a building featuring statement curves, knowing shallow ones still look fantastic but aren’t ‘premium cost’.
An 8‑metre radius will use the same plank thickness as a straight beam and is typically only around 50% more than a straight beam. Could this be the sweet spot you’re after?
| 8m radius curves | £1,300.00 |
| 4m radius curves | £1,900.00 |
| 2m radius curves | £3,300.00 |
| 1m radius curves | £5,700.00 |
Glued timber ready to go into the clamps
Getting excited about curved glulam designs
Ok, so we know cost isn’t a deal-breaker for shallow curves, but it will vary with tightness.
Still, the clamping process gives us lots of flexibility, so let’s allow ourselves to get a little excited about design possibilities. As long as the curvature isn’t impossibly tight, if you can draw it, we can probably make it. In the past, we’ve manufactured:
- S‑shapes
- compound curves
- freeform, non‑circular shapes
- “random” curves that simply follow a designer’s line
Glulam can do far more than just the arches an architect might think about, so you don’t have to limit what you want to do.
Curvy and wavy glulam in carpentry
How far can curved glulam go? Thinking big (or small)
The tightest radius we’ve made is around 750mm, which needed very thin lamellae and careful handling. There’s a good example of what’s possible in the distinctive design of the Cynefin holiday pods, and one of the largest curved structures we’ve made was a footbridge in Northern Ireland. Here, we made beams around 27 metres long with a span of roughly 25 metres bearing‑to‑bearing.
We thrive on the most intricate and complex designs, but we’ll equally help you balance your budget with a design that works.
You can see the Cynefin holiday pods and other interesting designs (including Pret a Manger, Heathrow) in our feature: Five Favourite Curvy Glulam Constructions
Curved glulam portal frame project during install
A series of tight glulam curves for a memorial project
Some final quick-fire questions about glulam curves
Do curved beams spring back after clamping?
Surprisingly, no… or at least, not much. If you clamp two curves together, they might come out with tiny variations between them, but movement is minimal. It’s as if they take on a new permanent shape.
Are curved beams structurally weaker?
Not inherently. Strength depends on lamination thickness, species, grade and overall section, just like on a straight beam. Everything we make is tested rigorously and signed off.
Are curves only for aesthetics?
Not at all. Tight curves can be structural (as in the Cynefin pods), and large‑radius curves are often used for long‑span roofs, bridges and canopies.
Can’t we just order thinner timber for tighter curves?
You can order timber closer to the final thickness to reduce waste, but that usually means an 8‑week wait for bespoke sawn material. For most projects, the number of curves involved doesn’t justify the delay, so the two factors tend to cancel each other out.
As with all projects, it’s about finding the balance between budget, design and time.
Does timber species affect how well it bends?
Yes, especially at tight radii, but we’ll guide you through all those options. For starters, larch can be more brittle when planed thin, pine tends to bend a little better, and spruce is the most common choice because of its predictability. We can help you make the right design choices.
Curves on your wish list? Let’s talk
The scope for curved glulam in your project is bigger than you think. If you can imagine it, we’ve probably seen it or made it.
Get in touch to talk a bit more about your plans. If you’re considering a curve, whether a gentle sweep or an ambitious S‑shape, we’re always happy to talk through the options.
You can also read some more about Glulam Arched and Curved Timber Beams, and Glulam Beam Manufacture, where you’ll also find a video showing how we make curves.