Insulating render internally below ground

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Hi we are renovating an old building which is solid brick at the front and stone at the rear.  We have started removing existing internal treatments, which have consisted of polystyrene sheets and plaster board.  We are looking to use the Cornerstone insulating render on the internal walls.

Our questions are

Do we need to wait until the walls are fully dry before we can use the insulating render?

The bottom 170mm of the wall is below the ground level outside can we still use the insulating render or do we have to use an alternative?

Can the insulating render be taken to the internal floor (solid floor on earth) or do we have to leave a gap to prevent bridging?

Many thanks

Justine Changed status to publish February 16, 2021

Thanks for getting in touch.
The drier the walls the better, but Insulating Render can be applied to damp walls. As it doesn’t contain any organic material it won’t rot, but the damper the wall the longer it may take to cure/set. For below ground it can be used, however there is the risk that excess water can be pulled through at this point. We have a product called Tanking Render, this is based on natural cement rather than OPC so its softer and more compatible with older buildings, this could be applied as a 20mm render beforehand to this below ground section to make it more resistant to water ingress.  It could be taken to ground but a small gap would be beneficial, this would depend on the floor covering etc and how this manages moisture.
Please let us know if we can be of further help.

Justine Changed status to publish February 16, 2021
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