webertherm M1 onto masonry

webertherm M1 rendering is a component part of the webertherm XP external wall insulation (EWI) system. Third party accreditation and specification reflects the renders use solely onto an insulant as the substrate and supporting carrier. It is appreciated however, most commonly in refurbishment that a render only solution is required onto

It's likely that a render-only solution is required in scenarios where it may not be practically feasible to insulate a reveal detail, render is required onto an adjacent outhouse, porch etc. Thus, the rendering is used just for aesthetic reasons to enable continuity of finish to complete small elevations or adjacent and abutting constructions where insulation qualities are not required. In this instance the following instructions are in order.

The construction should be:

  • Inherently durable, and should be formed out of moderately strong materials
  • Free from cracks, loose friable and spalling materials
  • Of a reasonable alignment, thus so the maximum thickness of render is uncompromised and is relatively consistent
  • Best practice and detailing i.e. 150mm above ground level, not below DPC and only on the vertical walling’s. With appropriate cappings, drips, overhangs & projections all in order
  • Free from paints, coatings, contaminants (salts, oil) or anything that may impair the bond of the products
  • Free from surface growth or removed by way of weber CL150 in accordance with manufacturers instructions


  • Apply weberend aid, 3mm in thickness, provide mechanical key by a forming a pronounced stipple with loaded roller, undertaken a minimum of 48 hours In advance of the main wall rendering.
  • Apply webertherm M1 to a finished thickness of 12mm scraped, spray roughcast or dashed, incorporating weber mesh cloth mid thickness.

We would not foresee this methodology as a solution outside of a 10m² to 15m². Where a project’s guarantee has been agreed the above advice would be acceptable.

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If you have any questions or would like assistance, please contact our technical team:

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