Alright lads am looking at a job, concrete floor extension been down for a couple of years but at the patio door they have come up short. As can bee seen in the pic by the looks of it they have miscalculated the pour of the concrete and put in a row of bricks with DPM sheet wrapped round it to try and bodge it. Will be going back next week to take damp tests from other areas and looking for suggestions.
The brick was already in place before the poor of concrete. The bricks should of been removed. This is common when the footings are done and bricked to DPC and concrete poured before measuring where the door way should be. The Fix - Remove one course of the bricks (there is no dpc there as it should be on top of them bricks) Then fold back the Dpm sheet and extend dpm so it now comes up the door. Make sure you tape the dpm sheets together with water proof tape. Next fill in with concrete 4/1 . Leave to dry ( 1 mm per day but in the size of the patch it will be faster) Next you should grind a groove between the two concretes where they meet together and apply a epoxy down the joint to bond the two together. This is to make sure that the two slabs don't move and crack your smoothing compound going over the top. To be fair its a easy job and should take about 2 hours , 1 bag of cement and 4 bags of sand with lite gravel mix.
I have done this a few times mate. Take bricks out, dpm sheet in, then in stages, I used stopgap base. till got the right level. Done that about 3 times with no problems.
Could use Ardex A35 Screed mix to fill the void after preparing like Matt said, A35 dry in 24 hours. Rapid hardening and drying cement for floor screeds. Used in place of Portland Cement in cement/sand screeds. ARDEX A 35 produces a floor screed that can be walked on after 3 hours and is dry enough to receive floorcoverings after 24 hours regardless of screed thickness or 4 hours when smoothed with ARDEX A 55. After 1 day the compressive and tensile strengths of an ARDEX A 35 screed exceed the acceptable minimum attained by a conventional screed after 28 days.
