Portal VS Purlin: 7 Considerations for Portal / Rafter Mounts

The portal is the most widely used frame for commercial/industrial buildings like warehouses, workshops and garages – and it’s little wonder. The structure is lightweight, highly rigid and strong, flexible in design, and easily constructed en masse for long buildings with a repetitive design. Monkeytoe combines integration and application of new technologies to provide seamless control over quality and consistency.

Below are 7 considerations when considering a portal / rafter mounting system.

It’s all about structural stability

To mount to the portal/rafter structure is to take advantage of a building’s inherent stability – without adding additional weight to the roof itself, or additional rigid support mechanical structures taking up precious floor space.

It’s a fast fix for existing buildings

Mounting directly to the building portals/ rafters is often relatively fast, and optimal when purlin platforms aren’t suitable. It’s ideal for existing roofs where the established purlins simply don’t have the capacity to safely support equipment on a purlin- mounted platform.

Portal/rafter mounting can be cheaper

Side-by-side, a portal/rafter mount will be more expensive than a purlin mount product. However, retrofitting an already-built roof with additional purlins will be considerably more expensive and cause a lot of tenant disruption – which means a portal/rafter mount soon comes out on top. Plus, there’s the additional design and fitting time that needs to be considered.

When comparing options, always assess the entire project’s costs to be sure you’ve made the right choice.

No leaks – no hassles

Yes, mounting feet are cut through the roof flashings. If done poorly, there’s a risk of leaks. Not the case for us – our boots and back flashings mean that we’ve greatly reduced the chance of ingress.

And since we cut through the roof to mount the feet on the portal/rafter, not the roofing metal, there are no hassles for roof maintenance.

Wide mounts are a new innovation

Portal mounting has only become a viable option for some applications in recent years thanks to technological innovations. Because portal/rafter mounting typically relies on long spans – that is, across a considerable stretch of a building – this can limit which materials can be used. In the past, the only viable option was heavy structural steel, but the sheer weight of this material can be detrimental to the building structure limiting the amount of weight you can put on the platform.

Aluminium has proven to be the most popular material in recent years. It has incredible span capacity, without imposing the same load as steel, without the risk of rot like wood, and without the regular maintenance of iron-based materials.

It is, however, more flexible, which is why it hasn’t historically been a great option when spanning long distances between portals/ rafters.

But if we want to look into truly 21st century solutions, then we’ve got to talk about carbon fibre composites and the XBEAM which is lighter and stronger than anything else we’ve seen. XBEAM utilises aluminium’s structural integrity and carbon fibre’s stiffness to deliver exceptional spans and strength.

Portal/rafter mounts are easy-access

Because the platform is installed on the portals/rafters, there’s a relatively clear space underneath the structure, eliminating the risk of debris build-up – and providing a clearance to get under the platform for any roof maintenance.

By contrast, purlin-mounted platforms have to be totally removed before any major roof work is undertaken. Not impossible, but worth considering for long-term work.

The XBEAM portal/rafter mount

We’ve designed the XBEAM portal/rafter mount to make things easier throughout the entire process.

Essential for any roof mounting situation, great or small, new or existing, XBEAM is ideal for situations when clients would like to realise instant savings over costly traditional structural mounting systems.

Firstly, an XBEAM portal/rafter mount is substantially lighter than a steel equivalent. How much so? If a traditional 10m x 10m platform might weigh up to 10,000kg, the XBEAM is a mere 3,500kg. Not only does that mean less structural stress (and so less high load bearing), but it also allows a greater loading capacity for equipment.

We’ve also developed our XBEAM to be fully isolated with a sealed construction and pre- engineered portal/rafter frame connections. Add to that the fact that there’s no risky or time-consuming hot works at height required, and the XBEAM’s modular, easy-fit design makes for a simple and fast fit.

The assembly of a purlin-mounted platform takes around 25 minutes per square metre, and all must be performed at height. We’ve designed our XBEAM platforms to be assembled on the ground and lifted onto the roof in complete modules, requiring just seven minutes of roof-level assembly per square metre of platform. XBEAM means safer working environments, and a massive reduction in risk to you and your team.

Find out more

Click here to download our latest ebook “Portal vs Purlin: The Mounting Showdown” to find out more about mounting solutions. Understand the science behind why portal / rafter mount? Why purlin? And what’s going to come out on top for your needs – now and into the future?

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