The market for flat roofing within the UK currently stands at roughly 16 million m2 per year, half of which is down to full scale refurbishment projects required to rectify material or system failure – a costly process.
Therefore, it is evident that more thought needs to be put into the decision to install a flat roof system at the initial stages of a project and there are a number of questions that should be answered:
Is a flat roof a long-term solution for a new build situation?
Compared with alternative solutions, multi-layer felt and modern single ply products have a limited life expectancy, with flat roofing material suppliers generally offering guarantees on their products of between 10 to 15 years. Some come with guarantees of 20 years, but these have a hefty price tag. In either case, the long-term suitability of these materials is highly dependent on onsite workmanship and the detailing of the interfaces and junctions.
I would suggest an alternative solution is the specification of a metal low-pitched roof, such as a standing seam or concealed fix system. These systems work down to a pitch as low as 1° and the jointing and connection details have been tried and tested. This system approach which utilises high performance pre-finished steel products, provides a durable, maintenance free result, for up to twice as long as many membrane solutions.
I have a flat roof installed which has failed, what are my options?
If your roof is repaired with the same or a similar system, this could result in a comparable failure in the future. The problem of permanently ponding water will also not be resolved. Therefore, I would suggest that a more appropriate solution would be to convert the current flat roof to a pitched roof using a lightweight steel structure.
The lightweight steel structure supports a profiled pre-finished steel roofing sheet, which provides weatherproof covering. This approach offers additional choices in profile shape and colour to change and improve the aesthetics of the building.
This also provides the opportunity to easily incorporate additional thermal insulation, which will in turn increase the energy efficiency of the building. As such, the flat to pitch option offers much more than just a simple replacement, it provides a complete solution with additional functionality and performance.
What are the key design issues when considering a flat to pitch conversion?
The most important factor to consider is the structural capability of the existing roof. This must be checked by a qualified person who can assess the existing structure and best advise on a suitable method of attaching the new roof.
Lightweight steel pitch conversion kits are available for attachment directly to the existing flat roof structure and some systems can span over the roof and transfer the loads down into the main structural frame or wall.
Our website discusses this in more detail.
By David Taylor – Refurbishment consultant at Corus Colorcoat®
Tags: building aesthetics, flat roofs, Lightweight steel pitch conversion, low-pitched roof, refurbishment
