Beam and Block and DPM and floating floor

[SillyBilly]

I am building an extension.  Have done the beam and block floor.  Plan to have 150mm celotex or similar standing on a 1200 gauge polythene dpm joined to downturned 450mm dpc.  I am not installing UFH and am considering a floating floor of glued 22mm t&g panels standing on the PIR or possibly engineered wood flooring.  Is that  suitable and do I need another dpm over PIR as not pouring screed on it?

[Russell griffiths]

If you don’t put a screed on top of the insulation how are you going to get your floor flat, I bet the block n beam floor is far from level or flat, also have you first hand experience of a floating floor. 

All the ones I have seen if you jump up and down in one corner the telly changes Channel all by itself. 

 

I personally would rethink this idea, but obviously that’s my opinion.  

[tonyshouse]

I worry about air leakage through the beam and block followed by infiltration into the room, cavity walls also leak.

 

I would have poly on top of insulation, then combined air barrier, vb and  dpm,  then trap it behind presumed skirtings sealed at doors and corners 

[SillyBilly]

Thanks for replies so far.  Didn't see them as no email notifcations received.  Still thinking about it

[Mr Punter]

You should have a polythene vapour control layer on top of the insulation.  The reason for this is because there is a risk that warm moist air from the house could get through the gaps between the insulation and condense on the beam and block.  Quite unlikely but ho-hum.