Asbestos Cement Roofing & Cladding Giromax

Asbestos sheeting was originally introduced as a lightweight alternative to commercial slate and tile roofing. Fibres of mainly white chrysotile asbestos provided the strength and flexibility to allow cement sheets to be pressed into standard profiles that carried a realistic 50 year life expectancy.

Manufacture continued until the early 1980s when the dangers of asbestos led to its replacement, mainly with PVA cellulose.

Problem: Aged Degraded Sheets

Old leaking asbestos roofs present a special maintenance problem. Sheets are fragile and often cracked while loose, corroded fixings add to lift and leakage.

The dangers of disturbing the asbestos sheet means even the simplest repair must be undertaken by specialist contractors to avoid airborne release of harmful fibres. Stringent disposal regulations means replacement is costly and hugely disruptive.

Over-sheeting adds weight, risks disturbing the sheet through fixing and may lead to condensation without addressing the underlying problem of deteriorating asbestos cement. This scenario is faced by thousands of industrial and commercial units throughout the country.

Treatment: Encapsulation Delcote ® Architectural Coating

A safer and more cost effective solution to the problem is total sheet surface encapsulation.

Delcote ® is the ideal system. The specification calls for the use of Seamsil ® 400 to seal bolts and minor cracks as standard before encapsulating the sheet with a fully breathing silicone membrane to provide an enduring flexible, waterproof solution.

Asbestos cement sheets are vapour permeable, often with a high moisture content. Unlike most coatings, Delcote ® provides a fully breathing membrane that will not crack or blister.


Encapsulation with Delcote ® means the sheets remain undisturbed, eliminating the considerable cost, disruption and stringent controls needed for the safe removal and disposal of the asbestos sheet.

Deteriorating cement, corroded fixings and long term sheet damage all contribute to a fragile leaking roof. Delcote ® repels surface water creating a fully breathing membrane that allows the cement sheet to ‘sweat’ whilst keeping rainwater out.

Problem: Loose fixings

The main problems encountered today on old asbestos cement sheeting are minor cracks and loose and leaking galvanised hook bolts, often with corroded threads that make it impossible to re-tighten.

These can be easily sealed with our Seamsil 400 specification by cropping and encapsulating the bolt with Seamsil Sealant and Basecoat onto to the asbestos roof sheet.

Treatment: Seamsil ® 400

The Seamsil ® 400 system uses proven Silicone technology, being unaffected by UV or extremes of weather and temperature and having exceptional adhesion to cleaned and prepared surfaces.

It cures to provide a tough elastic seal, effectively encapsulating the damaged area to restrict further deterioration, demonstrating for fixings, its proven track record in corrosion control.

The Seamsil ® system has been developed against a background of decades of experience of roof repair and is designed to be user friendly in application, comprising a gun applied sealant followed by a coating of brush applied Basecoat and coloured Topcoat.

Seamsil ® is unaffected by weathering conditions such as sunlight, ultra violet radiation, rain, snow and temperature extremes. The excellent weatherability and high temperature movement accommodation enables the system to perform after many years of exposure.

Latest News

Posted on Tuesday, December 3rd

We are pleased to welcome the newest member of our technical sales team. Jane Turner brings a wealth of technical.

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