UK construction programmes that extend through autumn and winter face a predictable productivity challenge. Rain, low temperatures and reduced daylight slow most trades. Indoor trades cannot start until the building is weather-tight. Where the build sequence has the roof going on in November or December, the months between bricklayers finishing and roof completion are months in which the partially built structure is exposed to weather it was not designed for.
Temporary roof structures, sometimes called scaffold roofs or weatherproof scaffolding, address this by providing a planned cover over the work area during the period the permanent roof is being installed. The cover is engineered, certified, weather-rated and removable. Underneath, the work proceeds in conditions much closer to indoor work than the alternative.
The economics of temporary roofs are not always intuitive. The cost of the temporary structure is meaningful. The cost it offsets, in lost productivity, weather-delayed works, and damage to partially completed elements of the building, is usually larger. On a typical residential scheme running through October to February, the productivity offset from a temporary roof can easily exceed the cost of the structure within six weeks.
The largest single benefit is on the internal trades that can start earlier than they otherwise could. With a temporary roof in place, plasterboard, first-fix electrics, and first-fix plumbing can proceed before the permanent roof is complete. The trades work in dry conditions. The materials remain dry. The drying times that follow plaster work do not get extended by ambient humidity. The cumulative effect across a phased site is significant.
The second benefit is on the roofing programme itself. Roofers working under a temporary cover work more productively than roofers exposed to rain. Tiles are laid on a dry deck. Underlay is fitted without weather pressure. The fixing schedule is executed accurately because operatives are not rushing to beat the next shower. Defect rates fall. Programme rate rises.
The third benefit, less visible but real, is on the protection of partially completed work. A bricklayer’s mortar joints exposed to a week of heavy rain perform differently from joints protected during the same week. Wall plates that get wet shrink and warp as they dry. Cavity insulation absorbs moisture and underperforms thermally. None of these is catastrophic. All of them are quality drags that the temporary roof prevents.
Globe Cambridge designs and installs temporary roof structures for clients who need them, and integrates the structure with the rest of the scaffold from pre-start. The temporary roof is not a separate procurement decision made when the weather turns. It is a planned element of the scaffold strategy on schemes whose programme runs through autumn and winter.
For developers and QSs assessing whether to specify a temporary roof, the economics depend on the months the build runs through, the size of the scheme, and the value of the productivity offset. As a rough rule, schemes running through November to February nearly always justify a temporary roof. Schemes running through March to October usually do not. Schemes that straddle the boundary need closer analysis.
There is also a programme certainty argument. A scheme that has committed to plot release dates based on a winter programme is exposed to weather-driven delay if no temporary roof is in place. Each delayed plot affects sales programme and cash flow. The temporary roof effectively buys the developer protection against weather-related programme risk.
For long-running schemes where the same site will experience multiple winters, the case for temporary roofs is stronger again because the depreciation of the temporary structure amortises across multiple seasons of use. Globe Cambridge’s larger temporary roof projects have included multi-phase developments where the structure was relocated across the site as the phases progressed.
Specifying a temporary roof at design stage is the right time to take the decision. Bolting one on partway through a winter that has already started is more expensive and less effective. The contractors who do this well, like Globe Cambridge, raise the question at pre-start so that the decision is made when it has the most value.
Talk to Globe Cambridge To discuss temporary roofs and weather protection through winter on your scheme, contact Globe Cambridge on 01223 890727 or email enquiries@theglobegroup.co.uk.
