Lightweight Roof Solutions for Over Roofing Pitched Felt Roofs

Pitched roofs, in built-up bitumen felt, were installed on thousands of houses and public buildings during the fifties, sixties and seventies and are, almost without exception, now well past the end of their effective lives.  

Apart from deterioration due to natural ageing, one of the principal reasons for felt roof degradation is the cracking or tearing of the felt caused by movement of the underlying structure, particularly through drying shrinkage and thermal changes. Whatever precautions are taken these factors can never be eliminated entirely.

Additionally, long-term weathering and ultra-violet attack cause gradual loss of bitumen from the surface and make the felt less flexible. Crazing, pitting and cracking may easily occur, allowing moisture into the fibres which can then also accelerate deterioration of the supporting roof deck.

Further problems can arise due to large amounts of water trapped under the felt, or from excessive condensation. An extra difficulty often encountered in refurbishment is that many of these lightweight roofs were designed at very low pitch, precluding the use of traditional roofing materials.

Total roof replacement is expensive and unnecessary. Adding a lightweight, visually attractive and permanent roof over the existing felt solves all the problems, keeps costs down and contributes to greater insulation values.

Before After


The Decra Lightweight Roofing Solution

The Decra lightweight roofing system provides the key to successful refurbishment. It is durable, has a traditional appearance and great aesthetic appeal that is so important in residential areas.

Adding an additional roof layer, with appropriate insulation between the ceiling joists, greatly increases the effective thermal insulation of the structure without major, extra expense.

Decra tiles are light - one seventh the weight of concrete tiles - and, provided the substrate is sound, can normally be installed over existing felt roofs at pitches as low as 10° without the need to strengthen the existing structure of the building.

As each Decra tile covers 0.46m2 and weighs only 3.06kg, dry-fix re-roofing can be rapidly completed causing minimum disturbance to the residents who normally remain in occupation throughout.

Decra Roof Systems offers a range of tile profiles and colours all sharing a traditional appearance of tiles and slates enabling specifiers to harmonise refurbishment with the predominant roof tones of any residential area.
For more than 30 years, the Decra system has been providing local authorities and Registered Social Landlords with the solution to their problems with pitched felt roof refurbishment, against a background of more than 50 years' worldwide roofing experience.

Decra is permanent and reliable. Approved by the Agrement Board and backed by a thirty-year weather security guarantee, Over twelve million square metres of Decra tiles have been installed in the UK and Ireland since the company was launched in 1977. That’s enough to roof 200,000 average terraced houses, of which many thousands are refurbishments of non-traditional housing.

Pitched felt roofed bungalow transformed by Decra

Pitched felt roofed bungalow transformed by Decra

Decra has a in-house nationwide team of technical experts on hand to provide advice in your office or on site. For re-roofing projects we offer a site survey and bespoke specification service as part of a total project package for complete peace of mind.  For local technical support for your current project and any future requirements, we can arrange for one of our technical advisers to contact you.

    Contact Us

    Contact Us

    To discuss your project in more detail please contact
    Your Local Area Manager


    Technical Support


    0330 123 4585



    Sales Enquiries & Orders


    0843 224 7400


    0843 224 7401


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