Permalayer™ is an anti-crack underlay designed for use over timber as well as green and cured concrete slabs and screeds. The unique Permalayer™ system enables cracks up to 3mm wide to be bridged without affecting the tiled finish. When used correctly Permalayer™ removes the need for costly floor build-ups such as plywood overlays. The layer enables the substrate beneath to move laterally, protecting the tiled finish from the detrimental effects of subfloor movement. A solid bed can also be achieved due to the flat nature of the underlay eliminating the problems associated with point loading.

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Permalayer MaterialPermalayer™ is suitable for use in conjunction with floors incorporating heating pipes.

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The following results were obtained from independent tests performed by Ceram Research on Permalayer™ :

  • The tile finish and grout joints were protected from the drying shrinkage normally experienced by green concretes and screeds, permitting tile fixing to commence a minimum of 48 hours after construction of the floor, with no damage experienced by either the tiles or grout joints.

  • When tiles were laid onto the Permalayer™ which had been fixed to tongue & groove chipboard fixed to 38 x 150mm timber joists at 600mm centres, using Norcros Rapid Porcelain tile adhesive. The timber floor achieved a mean failure load of 6.2kN at a mean deflection of 16.3mm with only the tile directly under load cracking after the timber floor itself had failed. The surrounding tiles did not fail and no cracking was noted in the tile adhesive bed. This exceeds the requirements of BS 6399-1 1996 Loading for Buildings. Part 1 Code of practice for dead and imposed loads which states that the maximum load a floor must resist for domestic, office and shopping areas is 4.5kN.

Permalayer usage chart