Tensile fabric structures have two main components:
A metal framework (usually steel or aluminium), and a fabric envelope that stretches over that framework.
Confusingly, there are a lot of different names for tensile structures.
You might see them referred to as:
While there are different types of tensile structures, the above names are all used to refer to the same general concept:
A robust structure made of fabric and metal.
Tensile is a special construction method.
It’s different from what we might call ‘traditional construction’, which uses bricks and mortar. Tensile construction uses steel and membrane instead.
(Which actually gives tensile a lot of benefits over traditional construction. We’ll come back to this later.)
First, a modular lattice framework is built out of steel components.
Then, a fabric membrane is rolled over the frame and pulled taut or ‘tensioned’.
Quick Note: Prefabrication
Usually, the steel parts of a tensile structure are made in a factory away from the construction site.
This process is called ‘prefabrication’.
Being prefabricated, once the components reach the construction site they can be assembled into the building frame relatively fast.
Because the materials are lighter than those used in traditional construction, tensile structures can’t rely on principles of gravity and rigidity like a traditional building.
Instead, they rely on a calculated balance of internal stresses to help the framework and fabric (also referred to as ‘membrane’ or ‘skin’) form a rigid structure.
This tension-based geometric construction is why tensile structures are sometimes called ‘tension membrane buildings’.
So, tensile structures have metal frames.
As we mentioned earlier, these can either be aluminium or steel.
This actually links to another important aspect of categorising tensile structures, which is whether they’re temporary or permanent.
Quick Note: Frame Material
If a tensile structure is made from aluminium, it’s most likely temporary.
If it’s made from steel, then it’s probably permanent.
It’s because of the aluminium-framed structures that many people think ‘tensile’ automatically means ‘temporary’.
But, as we’ve covered above, most steel-framed tensile buildings are designed as permanent structures.
When it comes down to it, answering two key questions will tell you whether you need a steel-framed tensile structure, or an aluminium one.
Some tensile structures are fully enclosed.
They have walls, roofs, and function just like a traditional building would.
On the other hand, some tensile structures don’t have walls.
Instead, they act as canopies and pavilions, giving shelter but not total protection.
A lot of the principles we’re covering today apply to both enclosed and open tensile structures.
For the most part, we’re focusing on enclosed tensile structures because that’s what we specialise in.
Tensile structures have a lot of benefits.
They’re sustainable, offer lots of design options and, as you’ll see in this video, people like spending time in them:
The best part?
They’re great for almost any project that needs a large indoor space.
Common applications for tensile structures include:
They’re especially popular at ports and harbours because they can be made to withstand very harsh environments.
The fact tensile structures can be made resistant to corrosion makes them popular waste and recycling buildings, too.
Though not all, some tensile contractors can create buildings that are clear span up to 100 metres.
That means there are no internal supporting struts or columns to get in the way.
This makes tensile fabric structures ideal for industrial handling facilities where large vehicles might need to move around inside, or for large sports training centres.
If you need a large indoor space, tensile structures are a great option.
Nine times out of ten the design, materials, and methodology make tensile construction the most cost-effective option.
You don’t even have to compromise on design.
Of course, tensile isn’t right for every project.
But if you’re planning a sports or leisure facility, film studio, aircraft hangar, warehouse, or any other project that needs large clear span internal space, tensile could be the right way forward.
Just take a look:
Suffice to say, sustainability is definitely a key benefit of this type of structure.
Whether you need an aluminium or steel-framed tensile building comes down to two key points:
Aluminium is ideal for putting up and taking down.
It’s not heavy, which makes it the right choice for smaller and more temporary structures.
But if your building will span more than 20 metres, or you need a more permanent space, it’s highly likely a steel frame would be better suited.
Steel is stronger and more durable. It can span greater distances more reliably and has a higher strength to weight ratio.
In other words:
You don’t need a lot of steel (relatively speaking) to create a large, strong tensile building designed to suit site conditions.
Tensile structures are often described as ‘lightweight’ because they don’t use a lot of materials.
(Which is actually a key cost and sustainability benefit of choosing tensile.)
But, it can lead to concerns over whether the structure will be strong enough to stand the test of time.
Really, ‘lightweight’ just means you need fewer materials to construct a tensile building than a traditional one.
(For one thing, a tensile building doesn’t need brick walls.)
Another reason you need fewer materials is because steel has an extremely high strength-to-weight ratio.
So, using steel as the skeleton of the building means you need even less material to create a strong frame.
A steel-framed tensile building constructed at Back Football Club on the Isle of Lewis withstood recorded wind speeds of 130mph for 5-7 hours in 2014.
Many nearby buildings were damaged in the harsh conditions.
The tensile building, which had been designed to suit the weather of the site, was not.
Otherwise, they have the same design possibilities as a traditional building, if not more.
In many ways, tensile buildings are less restricted than traditional buildings because they aren’t tied to the same boxy shape.
The nature of the steel frame means it can be adjusted to create dramatic shapes and profiles.
Take the Doctor Who Experience, for example:
The fabric, too, can be manipulated for interesting visuals.
It’s also possible to have coloured fabric, though this might impact the amount of natural light that gets into the facility.
On the outside, the fabric can be printed with logos and other designs.
Coloured or wooden cladding is another way to go, either for branding or to fit in with the area.
For example, cedar cladding is a great option for rural settings because the building blends right in:
Trailfinders Sports Club, Ealing
It’s telling that architects will often incorporate tensile buildings into more complex projects.
They’re a more economical option, but they can still be designed with aesthetic appeal.
In a lot of large school developments, for example, the architect will opt for a tensile sports facility to free up the budget for the rest of the school building.
York St John University connected a fabric facility and traditional building
Plus, if windows are a requirement, some tensile contractors can incorporate glazed gables into their structures.
This effectively gives a window wall (as seen in the picture of the University of Kent’s sports facility above).
It really just depends on what you plan on using the space for.
For waste management and general storage, it’s common for the building to be left unheated.
Even for sports use, most tensile structures can hold a good enough ambient temperature that additional heating isn’t needed.
However, in those cases where heating is necessary, there are two main options available.
Both come down to how many membranes the building is covered with.
Those membranes are also known as ‘skins’.
It’s common for single-skinned tensile buildings to be heated to an ambient temperature.
The other option is a double-skinned building, which can be fully heated and insulated in compliance with Part L2A building regulations.
Bear in mind that with a double-skinned facility you can lose the natural light benefits.
That’s because the cavity between skins is often filled with insulation to provide the extra heat.
It’s a common misconception that all tensile structures are temporary.
While it’s definitely true that some tensile structures are designed to be taken down after a certain amount of time, other tensile buildings are meant to be permanent.
As we covered earlier, some tensile buildings use aluminium frames instead of steel.
These can be easier to relocate but may be compromised when it comes to long-term structural strength.
Technically, even steel tensile buildings could be relocated.
However, because the steel structures are often designed to suit the specific conditions of a site, they may not be suited to the conditions of a new location.
The ground, wind, and snow loadings at the new site could all be different to where the building was originally designed for.
If you’re planning on moving a tensile structure, it’s always best to check the design factors against the conditions of the new site.
An experienced tensile contractor should be able to help you with this.
Like any building, how long it will last mainly depends on the materials used to build it.
Which is, of course, down to the contractor.
Some tensile contractors offer warranties up to 25 years on the steelwork and up to 10 years on the membrane.
In reality, a high-quality membrane could be expected to last more than 35 years without needing to be replaced.
When it comes down to it, the life expectancy of tensile materials is similar to that of any other construction material.
Just because it’s tensile, doesn’t mean it’s temporary.
The materials (and people) are also subject to the same fire regulations as traditional buildings.
For additional peace of mind, look for a contractor that uses fire retardant membrane.
As with any building, if any damage does occur it tends to happen at a low level where there’s pedestrian and vehicle traffic.
So, we clad the bottom two and a half metres of the tensile building in steel.
That way it’s damage-proof, and the steel keeps the building contents secure.
Although, if the fabric were to be damaged, it’s wouldn’t be the end of the world:
Damaged fabric can actually be quickly and easily repaired using a process called ‘fabric welding’.
Any building that’s going to be in place for more than 28 days will need planning permission, even if you own the land.
Bear in mind that your Local Authority may have certain conditions you’ll need to meet in order to secure planning permission.