Wethan 275 Systems

Approved for use on

Flat Roofs 

For use as glassfibre-reinforced waterproofing on flat roofs with limited access, and as a waterproofing with localised reinforcement on pre-coated
metal roofing sheets and fibre cement roof sheets

Substrate

Aluminium Concrete Fibre Cement Mastic Asphalt Metal PUR or PIR Insulation Reinforced Bituminous Membranes Steel Timber 

For use in the following specifications:
• as a fully reinforced system on flat roofs with limited access on:
— concrete (primed and unprimed)
— asphalt
— bituminous roofing membranes, including mineral surfaced
— galvanized steel
— non-mineralised bitumen roofing membranes on plywood
— liquid-applied bituminous roof coating
— aluminium paint
— polyisocyanurate (PIR) foam insulation boards in conjunction with a specified carrier membrane
— existing polyurethane roofs
• as a locally-reinforced system on existing fibre cement (including asbestos) and plastisol-coated metal roofs.

Durability

25 Years 

The locally reinforced system will achieve an initial life expectancy of at least 10 years and the fully reinforced system will achieve an initial life expectancy of at least 25 years.

Installation Requirements

Installation of the systems must be carried out only by specialist roofing contractors trained and approved by the Certificate holder.

Fire Safety

When tested to DD CEN/TS 1187 : 2012 and classified in accordance with BS EN 13501-5 : 2005:

• a system comprising a 9 mm calcium silicate board, Wethan 141 Primer at an application rate of 0.125 ℓ·m–2, a base coat of Wethan 275 at an application rate of 0.5 ℓ·m–2, and a top coat of Wethan 275 at an application rate of 0.5 ℓ·m–2 achieved a BROOF(t4) classification
• a system comprising a primed 12 mm plywood substrate, a vapour control layer, an 80 mm thick, glass-faced, polyurethane insulation board bonded with a polyurethane adhesive and primed on the upper face, a selfadhesive carrier membrane, a base coat of Wethan 275 at an application rate of 1.0 ℓ·m–2, a layer of Weplus 225 CSM, and a top coat of Wethan 275 at an application rate of 1.0 ℓ·m–2 achieved a BROOF(t4) classification
• a system comprising a 9 mm calcium silicate board, a base coat of Wethan 275 at an application rate of 1.0 ℓ·m–2, a layer of Weplus 225 CSM and a top coat of Wethan 275 at an application rate of 1.0 ℓ·m–2 achieved a BROOF(t4) classification.

The designation of other specifications, eg when used on combustible substrates, should be confirmed by: England and Wales — test or assessment in accordance with Approved Document B, Appendix A, clause 1. Scotland — test to conform to Mandatory Standard 2.8, clause 2.8.1(1)(2) (1) Technical Handbook (Domestic). (2) Technical Handbook (Non-Domestic). Northern Ireland — test or assessment by a UKAS-accredited laboratory, or an independent consultant with appropriate experience.

A roof incorporating the fully reinforced system has been tested to DD CEN/TS 1187 : 2012, Test 1.

Both systems, when tested for reaction to fire to EN ISO 11925-2 : 2010 and classified to BS EN 13501-1 : 2007, achieved Euroclass E.