Roofing 934 views Aug 03, 2018
Flat roofs - failure does not have to be an option

With ever-greater pressure being applied to the private and commercial sector purse strings, the need for building projects to be completed on time without minimum fuss becomes more significant writes James Wilkinson. There is little margin for error for contractors working to tighter-than-before deadlines, and that includes ensuring the correct specification of a waterproof, durable flat roof system. But what are the challenges facing architects and contractors when selecting suitable flat roof insulation? And why do such roofs sometimes fail? 

As a building’s first line of defence and prominent thermal feature, a roof must maintain long-term, maximum performance. Therefore, every aspect of its installation should be considered to ensure it remains watertight, problem-free and energy-efficient during its lifetime. The specification of bespoke, single-layer tapered systems can help alleviate risk when it comes to flat roofing. This outcome is easiest and best achieved in conjunction with Gradient, a specialist roof insulation manufacturer which works closely with customers on the design and manufacture of tapered solutions for a wide range of roofing applications.

Fitting solution

Placing the insulation process - from start to finish - into the hands of highly-experienced and skilled professionals not only maximises control standards in roof design, manufacture, performance and sustainability, it results in a better-conceived flat roof which is improved in value, performance and complies with all relevant legislative standards.

Gradient is able to supply specialist technical support to provide customers with flat roof solutions - whatever a roofing project’s stage. However, it’s fair to say most problems occur when clients fail to engage such companies at the very start of the roof specification process which minimises the risk of future problems. The close proximity of door thresholds to roof decks, for example can result in underperforming U-values and is a common issue. It’s an oversight which can lead to water-ponding and possible insect infestation, but can easily be avoided with early involvement from Gradient.

In such cases, a tapered roof insulation scheme can be applied, but the thermal performance will not be as good as it ought to be due to the aforementioned fault at the design stage. Encouraging developers to consider roof insulation performance long before they start construction is key to trouble-free roofing. When a building’s shell and certain fixtures and fittings are in position before roofing issues have been fully-addressed, it can often lead to height limitations being imposed on the insulation installed. Thus, flat guttering, the same thickness as the insulation is seen as a solution. Whilst this might be seen as a perfectly acceptable system for installers, developers would quite reasonably prefer a completely run-dry roof on which water is pushed to all available outlets.

Condensing the risk

Constraints on insulation height will sometimes rule-out the use of a fully-tapered roofing scheme, therefore a compromise on a particular roofing detail may have to be reached. It could lead to a roof design which doesn’t necessarily reflect best practice, but is nonetheless the best scheme with all factors considered. Compromise can take the form of a lower U-value, or the installation of a hybrid roof scheme in which insulation is applied below the deck. The latter solution is not ideal, as condensation is often a by-product. However, roofing firms such as Gradient are able to carry out calculations for a hybrid roof that will eliminate the risk of condensation.

Whichever roofing insulation specified, its performance is only as good as the installer. Selecting a proven contractor to carry out installation work is vital - a task becoming more challenging by the day with Britain facing its biggest skills shortage for a generation, particularly in the roofing industry. If a contractor omits to fully-tackle air gaps, for example, in a perfectly-designed roof, the potential for condensation remains.

Stark assessment

For developer, contractor and customer, time is money in the construction industry. However, quality must not be lost in the rush to reach the deadline. For refurbishment projects in which an existing roof is overlaid, Gradient is able to design a tapered scheme, with surveys made all the easier due to the visibility of the building’s falls. It’s part of the company’s service to carry out the same assessment when a roof is stripped to its deck. Time restrictions will often lead to contractors refusing the offer of a second visit, even though the stripped roof could reveal a deck to be damaged or uneven and in need of a rethink as to how the insulation should be applied to improve its long-term performance. Again, the answer is good preparation. Building extra time into a roof’s installation before installers arrive on site will help avoid unseen issues which may crop-up as the process continues.

Quality roof insulation, which protects against the ravages of the elements and time, as part of a long-term, waterproof system, doesn’t arrive by accident - it’s most definitely the result of excellent design and installation.


About the author: James Wilkinson is Design Team Leader at Gradient