insulation under damp tray

[chrisbrick]

hi just a quick one if your building a cavity with a damp proof tray and the rest of the cavity is 100 mm drytherm full fill. can you still use the same stuff under the tray . im talking at ground level ,

 

[mikric]

Why would you want to use mineral wool bellow dpc level ? this would not be acceptable, the insulation should have been sorted from the inside (perimeter insulation)before the floor slab was laid.

 

[chrisbrick]

dont think i have explained that right the bottom of the tray sits on dpc level then gos up and sits on the thermo block. so what im saying is i have 225mm under the tray that is above finnished floor level . hope this makes more sence

 

[chrisbrick]

any help or advice would be very wellcome

 

[noseall]

Cavity batts, i.e. Dritherm etc can be used sub-dpc as they are guaranteed not to wick water.

 

[chrisbrick]

ok thanks let me start from beginning. im building a extension for a friend its 2 skins of blockwork with 100mm cavity full fill inulation. i built up to dpc for him. and left him to concrete cavity . unfortunately he never listened right and concreted within a 100mm of dpc instead of 225mm. So the building inspector said put in a tray to get over it . which makes sence . But i was not sure if tray went in then sat insulation on top which to me dose not really do its job so iwas just checking that you can still use the same insulation under tray so at least the tray is in at an angle so any water runs straight out the weep holes.