Getting down to the detail of specification at the start of a project can save you time, money and hassle.
Our Operations Manager, Ben Haveron, gives his top tips for getting the spec right.
Main contractors are always under pressure to deliver projects within agreed timeframes and within budget. And as day follows night, this burden generally gets passed along the supply chain to the cladding and roofing contractors. However, in our experience this can sometimes lead to sub-contractors overlooking vital details during the specification of façade systems. And that can come back to bite them at the end of the project.
Based on our 25 years’ experience of working with architects, specifiers, main and sub-contractors, here are our top five tips to ensure you get cladding spec right from the outset.
Safety first – In the aftermath of Grenfell the correct specification of cladding material – especially on buildings over 18m in height – is rightly top of the agenda. Is the material you are being asked to fix to the building suitably non-combustible? The consequences of the wrong material going on the wall don’t require elaboration.
The cladding panels may be tried and tested, but get advice from those in the know to make sure all components in the entire fixing/framing system are rated and approved. It’s a few quick phone calls to ensure you’re not potentially putting people’s lives at risk – and your firm in the dock.
Don’t be fooled by ‘consultant speak’ – the current economic climate can make it tempting to cut costs – which is usually carried out in the name of ‘value engineering’. Subbies need to be wary of this as they may end up carrying the can in the event of system failure. In an effort to achieve the lowest price, it’s tempting to source materials and associated components from different manufacturers and then assemble them as a cladding system, when it is nothing of the sort.
Unfortunately, this results in a system that has no approved design, no U-value calculation confirmation and no tested fire boundary rating. This raises serious issues for the structural integrity, thermal performance, fire performance and lifespan of the materials and has serious implications for the building owner. In the event of a problem, there is no recourse to a sole manufacturer and there is no system warranty – however as the contractor, you may be in the legal firing line.
Devil in the detail – Cavity depths are a vital aspect within any cladding system design, but it’s amazing how many contractors end up asking us, the supplier for technical advice on this issue. It’s a key calculation within any façade system and affects the insulation spec, subframe spec, U-value and overall price of a project. It also has to be right as the cavity depth affects the interface with other systems. Get it wrong and the whole building will look dreadful.
Our advice is to understand the importance of this calculation and ensure you get the correct figures from the drawings. Don’t ever resort to guesswork.
Size matters – When it comes to panel sizes, it’s vital to get clarity from the outset, as this can have a huge impact on the amount of waste (and so cost) of a job. We understand that it’s often difficult to obtain exact sizes of panels at the beginning of a project, but an indicative projection of panel sizes required can make all the difference.
A higher level of detail enables us, as the supplier, to look at fixing systems and whether we can utilize 6 or 9 fixings per panel, for example. Fixings costs account for a surprisingly high percentage of cladding systems, so it’s really important to get this nailed down early on.
Similarly, waste is another issue that is hugely affected by badly informed panel size specification. Without accurate indication of panel sizes, it’s impossible to calculate the amount of waste, which can range from 5% to 70% on any given job. That’s an incredible range, that needs to be managed effectively to reduce waste and cost.
Consider offsite fabrication – this is a major trend within the wider building industry. And the cladding sector is increasingly reaping the benefits of offsite fabrication too. When panels arrive cut-to-size, drilled, have brackets already attached and are correctly packaged, all that is required by the contractor is to lift them off the pallet and hang them on the frame. That clean, simple process is becoming much more popular.
This approach cuts out machining on site. Not only is space limited, you also have dust control issues, high material wastage, a poor environment to fashion expensive architectural cladding panels and the problem of waste disposal.
There are, of course many other important issues – such as transport, logistics, packaging, cutting accuracy and site safety – that deserve careful consideration, but these five points are a good starter for ten to make life easier for sub-contractors in the highly competitive cladding market.