House to conservatory DPC with doors removed

31 Mar 2022
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United Kingdom
Hi, confident DIYer but never done something like this before... we've recently had our conservatory upgraded with a solid lightweight roof and new frame and glazing and built up the existing dwarf wall to full height (block and Brock with cavity) adjacent to the neighbours (previously just opaque uPVC panels). The room is pretty really well insulated now and we have taken out the sliding doors adjoining to the house to make it a more usable space.

I want to make sure the DPC is continued across the gap which has now been created where doors taken out. I plan to fill void with expanding foam, cut down to top of brick level, lay DPC across (tucking under house side) then screed on top to required finished floor level. Would this be okay? Also thinking I could use waterproofing paint at join between existing DPCs and new piece I add in.

There will then be insulation boards, elec underfloor heating and laminate on top.

Thanks in advance


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In case anyone has a similar issue, on the advice from a friends dad who is a very good builder, I ended up filling the cavity with 3:1 (sand:cement) screed, then once that had fully cured, painted with liquid damp proof membrane (£22 tin from Wickes). I did 2 coats, then laid a piece of polythene sheet and used the liquid DPM to stick it to the protruding pieces of DPM under conservatory and house to give a real solid continuous DPM. Will let that fully dry and then screed on top to required finished floor level.

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