Welcome to our Frequently Asked Questions:

What is a tie bar, why might I need one?

A tie bar is a systemised set of tubular elements that provide a connection between the bottom chords of roof trusses on a duo-pitch roof span. This system prevents the roof from spreading under large downward loads. When laced effectively, it also provides additional resistance against uplift forces. It may be considered for projects requiring a large span, projects subject to heavy snow loads or downward wind loads, or projects with limited tying possibilities.

What is the biggest span achievable?

This is very much subject to a variety of factors, including but not limited to:
• Location
• Environmental loads.
• Duration of project.
• Bay size.
• Support structure.

In moderate climate and exposure the following maximum spans can be expected:
• 450 series – in excess of 20m.
• 750/780 series – in excess of 30m.
• Asterix HD – in excess of 50m.

Why does my monopitch roof need to be at a 15 degree pitch?

A 15 degree inclination allows water to run off the roof without excessive water depot build up, avoiding water ponding and ingress in to the sheet tracking. Use of DeepFlow™ tracking allows for roof pitches to be made shallower and has been proven on spans pitched at 10 degrees.

What is the weight of UNI Roof/AHD as a system?

Based on 2.5m bays UNI Roof is 8-10kg/m2 and Asterix HD is 13-15kg/m2.

Can my tie bar be laced in scaffold tube to enable compressive and tensile capacity?

Yes. A quicker alternative is to use DESSA bracing elements.

How high can my UNI shelter go before I need to consider a vertical beam?

It is recommended that no taller than a 2.5m standard should be used on a UNI shelter.

I only have a four hole spigot, will my D78 beam still achieve its full capacity?

Providing a four hole connection will result in the joint governing the strength of the overall beam. Therefore the capacity of the D78 beam will be reduced. Details of the reductions are shown in our technical information sheet TIS17001.

Can I connect puncheons to the posts of a D78 beam?

No. According to EN 12811-1, cl., alloy tubes should not be connected to if their thickness is less than 4mm. The posts of the D78 beam are less than this. Full guidance on where to connect puncheons across our full beam range is shown in Beam User Guide USG001.

Can DESSA quick release pins be used on vertical bolted connections of system scaffold standards?

For standards of 48.3mm diameter, quick release pins AF0001 can be used. These pins are designed to suit a 12mm hole with 48.3mm outer diameter tube.

Are the roof sheets re-useable?

Yes. Care should be taken to pack and store the sheets following use. They should be inspected for damage, dried and pan folded with no sharp creases. We recommend they are stored in bags and inside.

How long do the roof sheets last?

Around 8-10 years, with a single job use of 2-3 years. We also offer a lightweight single use sheet and a heavy duty sheet for more onerous projects.

What is the minimum slope for a mono pitch roof?

To TG9:20, the minimum advisable pitch for a monopitch roof is 10 degrees. We advise 15 degrees to avoid such issues as water ponding and deflections in tracking joints. Our DeepFlow™ tracking allows for roof pitches to be made shallower and has been proven on span pitched at 10 degrees.

Why are roller braces needed?

Roller braces are not structural; however they are required for two main reasons:

• To assist sheeting installation by providing a rolling point at directional changes.
• To ensure the sheets are evenly tensioned.

Why are alloy track spigots needed when using DeepFlow™?

Alloy tracking spigots are used as an installation aid ensuring adjacent lengths of track are secured to each other and to prevent separation and sliding.