Welcome to our Frequently Asked Questions:

What is the safest method to build a roof?

The rollout method is the safest of the roof erection method as it allows the operators to erect the roof from a safe working platform (being a stepped gable end scaffold).

Is there a CISRS course for roofs?

There is no certified course for temporary roofing. We offer specific product training and first-time site hand-holding to assist with product familiarisation and site applications.

Do I need to be a qualified scaffolder to erect a temporary roof

Yes. Temporary roofs are complex structures that can impart large forces into the scaffold and supporting structures. Additional experience and knowledge is required to ensure safety and works should be only be undertaken or supervised by advanced level scaffolders.

Do I need to have drawings and calculations for every roof?

Yes, scaffolds with temporary roofs are Encapsulation Constructions as defined by BS EN16508 and beyond the scope of ‘Basic Scaffolds’ as defined in TG20. Temporary roofs are complex structures that can impart large forces into the scaffold and supporting structures, the overall stability and integrity of the structure needs to be assessed and detailed by a qualified and competent Engineer.

What additional design measures are needed if I add a temporary roof to my scaffold?

Temporary roofs are complex structures that can impart large forces into the scaffold and supporting structures, therefore the overall stability and integrity of the structure needs to be assessed and detailed by a qualified and competent Engineer. As a general rule, a scaffold supporting a temporary roof will require more anchors, bracing and ballast than a physically tied independent scaffold.

Do DESSA supply risk assessments and method statements for temporary roofs?

We supply designers risk assessments as part of our contract design service and can offer advice and examples of risk assessments and method statements to contractors involved in erection of temporary roofs.

Do your roofs fit any scaffold? How do I connect the roof to a scaffold?

Our temporary roofs can be fitted to any supporting scaffold structure. We provide support components to integrate seamlessly with system scaffolding and a range of lattice girders to provide a continuous roof support in installations where the supporting scaffold and roofing members do not align.

How do I open a roof for crane access?

This can be achieved through rolling roofs or pre-planned “access bay” positions. Having a rolling roof over an opening, and moving it to one site is a quick and efficient way to open the roof. Installing horizontal braces to the underside of the top chord on the unbraced bays allows a fixed roof to be easily accessed by removal of sheets and horizontal braces.

Can I lift more than a pair of braced bays at once?

Yes. Multiple bays can be erected on the ground and lifted into position. A number of factors need to be considered to achieve this such as crane capacity and reach, the availability of lifting beams or the possibility of installing secondary trusses through the roof beam lines for stability.

Can I retro-fit a tie bar on my installed roof?

Retro-fitting a tubular tie bar to a previously installed roof is difficult. For this reason we always recommend the tie tube system is installed at ground level where the roof can be lifted and lowered to ensure hole alignment and an easy fit of the elements. A tension cable can be installed following roof installation, we recommend our connection plates are pre-installed prior to roof bay installation to provide a solid connection point for the tension cables.

How can I terminate my excess sheet length?

There are a series of ways to achieve this, all of which are documented in the user guides. Excess sheets can be secured to the scaffold or returned into the roof space.

My roof is leaking, why?

If built correctly and subject to normal weather conditions, our roofs are leak free. A number of factors can cause leaks such as:
• Monopitch roofs built at an insufficient angle.
• Damaged components such as tracking ends and tracking spigots thereby not creating a seal at tracking joints.
• Incorrect installation procedure followed.
• Inadequate sheet tension.
• Supports not level introducing a twist into the roofing bays.
It should be noted that use of DeepFlow™ profile eliminates the possibility of leaks.

Do DESSA provide any anchoring solutions?

We provide a variety of components that can provide anchors such as bolted top plates and offset shear anchors. We also provide design and manufacture services on any component to achieve the desired anchor solution.

Can UNI Roof bracing be used for lacing and bracing of beams?

Complimentary lacing and bracing kits can be obtained for a number of our beam series. Use of these kits minimise weight and assembly times.

How can I work out the erection time of a roof?

As a general rule of thumb, you can expect four experienced operatives to achieve 250m2 in the first day of operation, with 400m2 each following day.

How do we seal the gap between sheet and ground when terminating a sidewall sheet?

Sheets can be fitting with “mud flaps” which provide additional coverage outside of the tensioning line. Our plastic Keder profile is ideal for sealing the Keder flaps to each other.

Do DESSA provide components to continue roof sheeting down the outside standard of a scaffold?

We provide a series of tracking couplers to achieve this. These connect to standards or ledgers to provide connection points for vertical or horizontal sheet tracking.

Do DESSA provide coloured sheets?

We can provide sheeting in a wide range of colours. For a specific colour please contact us via our online form or contact info@altrad-dessa.com.

Why use DESSA’s sheet tensioning bar instead of scaffold tube?

The tension bar features pre-drilled holes for locating the sheet pulling bar assembly and is colour-coded for easy recognition on site.

What sheeting types do DESSA offer?

DESSA offers three main types of roof sheet:
• 360 gsm for light-weight single use operations.
• 610 gsm standard offering.
• 910 gsm for heavy duty requirements.
These can be supplied in roof sheets, valance sheets, gable sheets, wall sheets and so on.

I want to build a rolling roof, what are my options?

We offer a multitude of runway and castor options. sysTRAX™ and TRAX UB can be used as a heavy duty solution with integrated anti-uplift. Trax tube holder can be used to make best utilisation of scaffold tube and fittings.

Do you supply guttering for your roofs?

No. We supply a gutter support bracket to enable a timber eaves board to be installed along the length of the roof to which off-the-shelf rainwater goods can be used. Gutter sizing is subject to calculation and can vary according to duration, location, inclination and down-pipe frequency. Gutter design should be verified by a competent Engineer.