Establish the design route before pricing
We need to establish the design requirement while the scaffold scope is being agreed. If the job needs calculations and drawings, the price and programme must allow for them. Finding that out with a gang booked for erection puts the job under avoidable pressure.
We check whether the proposed arrangement fits a recognised TG20 configuration or the relevant system guidance. Where it does not, we bring in the competent scaffold designer. We do not make the site fit an assumption in the quotation.
Check the actual arrangement against TG20
A compliance sheet needs to match the scaffold we are providing. We check the configuration and site conditions, including the loading, boarded lifts and ties. Sheeting or a restriction on fixing positions can change the requirement.
For a suitable independent scaffold, TG20 gives us a recognised route. It is not a document to select afterwards because it looks close to what has been erected.
Situations that commonly require design
HSE guidance identifies a range of scaffold structures that normally require bespoke design. These include temporary roofs, slung and suspended scaffolds, marine scaffolds, façade retention, many free-standing and cantilevered arrangements, pedestrian bridges and walkways, lifting gantries, power-line crossings and structures outside recognised system guidance.
Much of our work involves restricted supports, unusual building shapes or loading requirements. On suspended scaffolds, temporary roofs, marine work and complex recladding jobs, the designer needs to be involved from the start.
Give the designer the full brief
We need the working area and loads, but also the restrictions that may not appear on the elevations. Where can we found the scaffold? What can we tie to? How will the gang get materials to it?
Tell us about coverings, hoists and planned alterations at the same time. Adding sheeting or increasing loading later needs review; it is not just another item for the gang to fit.
What a controlled scaffold design should show
A scaffold design should give the erection team enough information to build the structure without making engineering decisions on site. NASC scaffold-design guidance identifies essentials such as the engineer and check engineer, site and drawing revision, scaffold dimensions, bay and lift arrangement, maximum working lifts, leg loads, couplers and the required tie type, configuration, frequency and testing.
Where a site condition forces a change, the design should move through a controlled revision process. Proposed modifications to a designed scaffold should be referred back to the design engineer and confirmed in writing; a verbal instruction should not replace an approved revised drawing.
Ties and anchors are part of the design
Where stability relies on structural ties, correct selection, installation and testing are part of the structural solution. NASC anchorage guidance distinguishes preliminary tests, used to establish whether a fixing is suitable for the base material, from proof tests used to check the quality of installed anchors. Tie patterns and frequencies should follow the design or compliance sheet rather than being adjusted informally on site.
Work through the erection sequence
We use the design discussion to resolve practical issues before mobilisation. An awkward support position or a restricted delivery route needs an answer while there is still time to change the arrangement.
The gang needs current information for erection and for subsequent alterations. If site conditions differ, we take the issue back through the design process.
Design on our specialist packages
Our Ferry Bridge scaffold needed a way of progressing from supported access into the suspended work beneath the deck. The heavy-duty crane loading bay at Shackleton & Moyana needed a different brief around the materials landing requirement.
That is why we start with the job and involve the designer where required. We supply TG20 arrangements and designed scaffolds; the right route depends on the proposed use and site conditions.
Planning a complex scaffold package?
Send us the drawings, proposed loads and site restrictions before fixing the scaffold layout. We can work through the access requirements and design input with your team.
Further reading
Related access: Designed and complex scaffolds.