How to seal 1200 gauge D.P.M after rebar?

[zappastix]

Hi

How can I maintain the integrity of the 1200 gauge d.p.m for a new floor - when the d.p.m is going to be
pierced horizontally by R10 rebar (6 metres wide extension - rebar every 200mm at centres)?

The rebar itself is a "Z" shape - the bottom section of the "Z" will be connected to a reinforced raft
filled with C35 lower down in the excavation.

The top of the "Z" locks the new floor to the raft.

The concrete slab will be 125mm.

The length of the rebar for the new floor (top of "Z") is 300mm

Looking on Google I've seen service pipes etc coming through d.p.m but I can't see how they seal
the cut.

Just as a side issue if this has any bearing - the structural engineer has changed what the original
architect had specified for the new floor, because I explained to him that the rebar will not line up
with the concrete but the insulation. So he said to put the insulation on top of the slab.

This is the original spec;

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The new floor is to be 100mm blinded hardcore bed, 1200 gauge
polythene d.p.m. followed by 70mm Kingspan floor insulation, 500 gauge
polythene vapour barrier, 125mm concrete slab and finished with
50mm C&S (1:4) screed towelled smooth.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is the revised spec;

In these cases the insulation goes on top of the slab. You adjust the concrete slab to let your
screed finish over the insulation to match existing floor levels. Your screed needs to be min of 65mm
when cast over insulation. This method will also give you a warmer floor.

Then there will be no conflict with reinforcement.

Any help/advice appreciated.

Many thanks.

Stephen

 

[^woody^]

I can't understand how this has been designed, or why whoever worked it out has not allowed for DPM? You should really sort it out with them

Would it be a case of sealing with a liquid product, or using a liquid DPM somewhere higher up or on top of the floor?

 

[zappastix]

Thanks Woody.

It all started when our 'new BCO to the area' gave us wrong advice about the footings (should have been 9" deep max). Ground collapsed (a lot) and the excavated section has now got to tie into the old floor that we removed to start a fresh.

This structural engineer was basically forced on us by the BCO (ongoing complaint with council). As I pointed out before, I have seen service pipes piercing the d.p.m - I was just wondering how they maintain the d.p.m.

Thanks anyway.

 

[Deluks]

Very confusing. There won't be a need for rebar in the insulation or screed. So any that protrudes above the concrete slab is probably surplus to requirements, (has it been incorrectly placed?)
I'd go with fitting it as best you can, accepting any breaches, and stick another dpm under the insulation, making sure it protrudes above the screed and or comes up to the level of dpc.

 

[Static]

Rebar piercing the DPM suggests it will be in contact with water which is bad.
Get the SE to look into it and come up with alternative..