Wethan 275

Waterproofing, UV-stable 1C polyurethane resin

Brief Description

Wethan 275 is a high-grade 1C polyurethane waterproofing layer for the flameless waterproofing of upstands and edges, as well as for waterproofing flat areas with and without fleece. As a highly elastic waterproofing layer, Wethan 275 is tested, approved and classified according to ETAG 005 as a category 3 product (service life of at least 25 years).


1-component, highly flexible polyurethane-based waterproofing resin

RAL colours

Wethan 275
is available in the following standard colours:



For exterior application at layer thicknesses > 1.7 mm, with or without embedded polyester fleece. However, its use for a particular purpose should be tested prior to application. We recommend embedding a fleece in areas susceptible to cracking, at upstands and edges and also at wall junctions. Designed for residential, commercial and industrial developments with light-duty mechanical and chemical exposure. For flat roofs, sloping roofs, PUR spray foam coatings, water tanks, water ducts etc. Wethan 141 is used as a primer on absorbent substrates such as concrete, stone or wood. Non-absorbent substrates, such as bitumenised sheets, metal etc. can be coated without the need for a primer. For further information about substrates and their preparation please refer to the Weplus substrates table. Wethan 275 absorbs substrate movements due to temperature fluctuations between – 30 °C and + 90 °C (depending on the layer thickness applied / use of fleece). Wethan 275 is supplied ready for use. Additional fillers should never be added, as this would reduce the flexibility of the membrane. When fully cured, Wethan 275 is resistant to water, seawater and waste water as well as to numerous alkali solutions, diluted acids, salt solutions, mineral oils, lubricants and fuels, and to many solvents. Depending on the substance, concentration and duration, exposure to chemicals may result in superficial colour changes, although this will not affect the reliable function. Polyurethanes with this composition have a strong tendency to change colour under the influence of UV radiation.

Properties and advantages

  • Wethan 275 hardens into a seamless, highly elastic and waterproof membrane. If applied at a sufficient thickness, Wethan 275 is root-resistant and offers a high crack-bridging capability for cracks up to 2 mm. Wethan 275 possesses a good water-vapour diffusion capacity. The waterproofing is UV-resistant and offers good chemical and mechanical resistance.


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Postal address

WestWood Liquid Technologies Ltd.
31 Morris Road,
Nuffield Industrial Estate
Poole, Dorset BH17 0GG
United Kingdom

+44 800 808 5480

Trade Association

  • LRWA
  • DIBt
  • NFRC
  • EOTA
  • BPA
  • BBA