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Wet underfloor heating and screed but external back door screed stops short of the frame bottom

Wet Underfloor heating and screed poured/laid over a 75ml insulation sheet, clear membrane however the newly installed pvc external back door screed stops short of the frame bottom and the frame is resting on 2 loose bricks (for the height that the new level of floor should be).
They are sitting on the old concrete floor that the newly laid underfloor heating, insulation and screed sits on.
What do i use to build up and do I use a dpc butting up to the new screed which has a dpc and insulation sheets?
A - sand and cement in a 3:1 ratio on top of the concrete to the underside of the frame. I would still need to build a step down due to the back door level changing about 100mm in height. I could build it in brick bedded into a mortar and levelled off.
B - I could tank the sides and floor with the same stuff used for my wet room that could stop any damp hopefully before I lay bricks etc.
Any help or suggestions would be great as I laid the heating and flooring myself but am not sure how to progress from here.

Apologies as it does sound confusing.
It is an existing built on kitchen 21 square meters that had a drop down to a concrete badly screeded floor of about 100mm that previously had slate that I removed.I removed the debris and laid a damp proof membrane and up above the new floor level to be poured. The celotex was then laid (75ml) and a clear plastic laid before the underfloor heating pipes and pins to hold it. Screed flow then pumped screed to a depth of average 50ml on top of the celotex with the expansion foam around the wall edging as well as the damp proof membrane already there.
A new door opening for the back door was opened up that had been bricked up and a door put in however this was after the screed was laid (my wife changing plans) therefore the gap under the new door is a brick high.
My query is what is the best way to infill this to rest the door frame on and how to create a step down to the outside level. Bearing in mind that the damp proof membrane and the expansion edging is holding back the screed poured a month ago.The bricks of the wall from the old opening from a 1920's build detached house in Cornwall are exposed after being cut through.

1 Answer from a MyBuilder Restoration & Refurb Specialist

Hi, Your post is a little confusing....
Could I ask a few questions
What are you building? if this is part of a new extension then it will be subject to building regs and you should have a drawing to work off?

So you have laid concrete?....then Celetex?....Then underfloor heating?...then screed?

If this is the case why did you not screed to the required height rather than leaving it short?

It sounds like you are going to breach the dpm/dpc which could have huge consequences further down the line.

2015-01-03T12:40:02+00:00

Answered 3rd Jan 2015

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