Screeding over cavity

10 Mar 2021
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United Kingdom
I am currently renovating my kitchen and am looking for some advice in how to screed over a cavity. A section of the old screed layer has broken up around the edge of the patio door threshold. At the moment, there is a dpm under the patio door overlapping the cavity and meeting the main dpc which comes up from the slab and wraps around the inner bricks (see pics). My question is, how do I go about screeding over the cavity? I’ve seen suggestions of placing a sheet of dpm in the cavity to form a trough (lining both the outer and inner bricks), filling with celotex or similar and then screeding over. Is this the best option? I just don’t want to be ripping the new flooring up after 2 years. Thanks in advance


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What should normally happen is the inner course should be removed to concrete slab level. Some slate or concrete board should then bridge the cavity gap. The dpm is extended and taped around this opening. Insulation will then go on top and the screed layer would go over the whole lot. (This is assuming its a slab insulation screed order)

To fix this perhaps you could try and knock some of the inner wall out and bridge the cavity as far down as you can, then build back up to level?

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