Glulam Frame Design: Scope, span, sizes and benefits when building with Buckland
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What is a glulam timber frame, what is involved in its design and when would you choose to use one for your project?
If you look up in your local swimming pool, the new atrium in your workplace, a riding arena, or even in a coffee shop as you wait to board a plane and spot timber, chances are you could be looking at a glulam timber frame. Here we answer some of the most frequent questions around glulam frame design…
What is a glulam frame?
Glue laminated timber (glulam) is structurally engineered wood, produced from bonding layers of timber together using a durable, moisture resistant adhesive. As it sets together, the pieces form a super-strong connection, meaning it will forever operate as a single piece of timber.
Glulam beams can then be used to design the frames of buildings, structures or extensions. This might cover an entire building from floor to frame, a glulam ridge beam to span a roof, or just structural elements like lintels. A glulam frame design can replace traditional steel or concrete to great effect and be left visible as part of the design.
Glulam frames allow us to produce creative designs, larger spans and unusual elements, such as curves. You have the vision, then we get to work with you to make it a reality.
For a closer look, look at this overview page: What is Glulam?
Types of glulam frame: What buildings can they be used for?
Well, how long is a piece of wood? We say this not just as a catchy phrase, but because the beauty of manufacturing and working with glulam is the flexibility.
Glulam frames are used in all types of buildings. From equestrian to commercial structures, and from swimming pools to places of worship, glulam timber works.
A larger space like a canteen or conference area would benefit from pitched/curve beams. A vaulted roof space in a residential property or barn conversion might be enhanced by trusses. Then, we’ve worked in ecclesiastical spaces, where a curved portal frame and steep roof pitch have built a sense of awe.
Take a look at our portfolio page for more inspiration.
Some of the most common glulam frames are:
Post and beam monopitch frame
These are simple and often the most cost-effective way of designing a glulam frame as a lot of cost of frames can be in the joints. Mono pitched braced frames are the cheapest way to cover an area and are commonly used for warehouses, private pools, and buildings where simplicity and budget is key.
Pitched curved beam frame
These are great as they are very structurally efficient – you have a deeper beam in the middle where more strength is needed. A lot comes down to a lack of big moment joints and metal work – in the middle of the beam instead of having a big joint with a massive plate in it you’ve got the natural shape of the curved beam. The depth of the beam varies in a way that tends to match the bending moment diagram (if you want to go into technicalities!).
These types of glulam frames need a low roof pitch under 20 degrees. They also need cantilever posts or cross bracing for stability – eaves moment connection like a normal steel portal won’t work here. These frames are commonly used for big buildings – horse arenas, community centres etc – they’re aesthetically pleasing, but a very efficient use of timber.
Curved portal frame – steep roof pitch
These are the same as the pitched curved beam rotated through 90 degrees.
We used to do lots of these, but they seem to have gone out of fashion – perhaps they’re considered a little retro now!
These frames suit a nice steep roof pitch like 40 degrees plus – buildings like offices, church renovations etc have commonly opted for this type of frame.
Straight beam portal frame with concealed and open joints.
It doesn’t matter what the roof pitch is for these glulam frames (curvy ones have an awkward gap in suitability between 20- and 40-degree pitch!).
The choice of concealing the joints is down to aesthetics – you can opt for a nice clean look if you conceal all the flitch plates and dowels, or you can leave exposed as a design choice.
For this it can include quite a bit of steel which adds cost in material, and install time can be longer as it can be a bit labour-intensive with all the dowels etc
These can be designed like the curved portal frames, and we can avoid putting the moment into the footing. Most recently we’ve used these for office and other commercial buildings
Canopies
Canopies are a simple glulam frame. We do a lot of these for schools, they span up to 13m and have around a 15–30-year lifespan. Is important to note that it is ideal to use larch glulam externally.
These canopies usually replace something that was put as a temporary solution, so are often budget dependent so use spruce with some coats of varnish – you wouldn’t expect them to last forever.
If these were internal (unless it were to get wet) they would last your lifetime. And that of your children and your grandchildren, although we’ve not tested this yet!
Trusses
Ok, so not technically a frame, but we can create a glulam frame for a roof by using glulam trusses. We can do big spans with a king post truss, and they can be quite cost effective and work well aesthetically rather than steel if you want exposed beams.
House extensions
A house extension is not really a structural form, but we use glulam frame design for most house extensions. We’ve included this as we do lots of house extensions and look at designs from an early idea stage to get an idea of cost.
We like the idea that a bespoke designed glulam frame for an extension can be cost effective.
What are the advantages of building with a glulam frame?
The case for glulam frame design is getting stronger and stronger. We want to share three key areas with you:
Environmental impact
You’ll know that carbon-footprint, sustainable living and the environment are huge issues, needing intervention from all angles. For us in the building and manufacturing industry, we love making a difference by working with glulam timber. By choosing glulam on your project, you partner with this us on this cause.
Buckland are committed to sustainable, local sourcing of wood and materials wherever possible (see our Locally Grown Story).
Take a look here for more information on the Environmental Benefits of glulam timber frames.
Cost-effectiveness
The variety of timber and design options mean you can choose materials that match your budget, as well as your design. Take a look at our recent article on costing a project.
There can also be savings to be made on using glulam in comparison to steel when using like for like simple beams. Glulam portal frames tend to be more expensive than the steel equivalent, but we can advise on how to make them as cost effective as possible.
Strength and flexibility
Glulam frame designs are unique in terms of the flexibility on offer to create your vision. Curves, bend and angles are all possible, and an advantage of using a natural timber product compared to steel or concrete. Alongside this, the glulam manufacturing process makes beams stronger and longer than normal timber.
At Buckland Timber, you also benefit from working with in-house engineers and designers. This makes the process much more collaborative and bespoke to meet your exact specifications.
Aesthetics that stand-out.
Glulam timber beams deliver on looks and glulam frame designs are increasingly the number one choice for many. They offer stand-out aesthetics in both contemporary and traditional settings, becoming a distinguishing feature that fits into your design.
You benefit from the variety of wood choices available when we start designing. This choice lets you match the timber to the look you want. The differing visuals of ash, oak, spruce, larch and others, let us tailor the design to find the aesthetic that works. Whether you want rustic ‘lots of knots,’ or clean ‘not-knots,’ your design will match the setting. Now that’s a mouthful to say, but we don’t shy away from a challenge.
Take a look here for more information on the Environmental Benefits of glulam timber frames.
What are the challenges and disadvantages of glulam frames?
In manufacturing and building, you’ll know your success is based on planning and expertise. It’s also based on how you overcome problems. All materials bring challenges and glulam is no exception.
Only some timbers are suited for external use, and they’ll need care and ongoing treatment, which you’ll need to consider (see External Glulam Designs). In addition, some cracking is inevitable as wood settles and dries. This is not a problem structurally but does make the moisture conditions during manufacture and construction a key factor.
You also need to consider the scope and size of the project. If designing from scratch, roof clearance is rarely an issue, but an extension or renovation may be more limited on height. Glulam beams need to be up to two times the depth of the equivalent steel, meaning we’ll have to assess if a full glulam frame is right for your project.
What does this mean for you? Always find, talk to and work with the experts.
Scope and size – how far can glulam beams span without support?
Our customers and clients are right to ask this question. It becomes relevant if it limits the scope of the design you can embark on.
For starters, glulam beams are remarkably strong. They can also be manufactured to lengths that far exceed normal timber.
Glulam roof beam span can reach 30m, which opens a huge opportunity for building type and frame design. But don’t worry, the options for larger buildings match the flexibility of the material. Other engineering elements such as trusses, combined with different configurations mean glulam frames with support can span much further than this.
You can find out more by look at our Glulam Beam Span Tables and Strength Grades.
Glulam frame design is all about your first idea. If you can give us a vision of what you want your space to look like (even if you don’t have the dimensions) we can help advise on what type of structure will suit best, what timber, and even what fixings (we know a lot about steel even though we’re glulam manufacturers!)
So, the next step? Speak to the experts. We’d love to chat with you.