Ventilation gap for loft floor insulation

[jamie765]

I am about to lay T&G floorboards down for my hip to gable loft conversion with rear dormer and not sure how far I should push the floor insulation roll into the edges of the dormer and eaves?

Read conflicting views when I googled and searched this forum, I can only assume that's because each case is different (ie. Old houses vs new).

My house is only 3 yeears old, the loft walls will have 90mm Celotex, whilst dormer flat roof and pitched roof will have 120mm + 25mm Celotex laid over. Cold roof structure

I've attached an image of what I think is correct - leaving a gap to allow for ventilation. Is this correctoor is there too much gap? I'll be gluing the floorboards down so no room for error really

 

[noseall]

There is no benefit of the cooler air getting anywhere near the internal floor space. If it is assisting external ventilation then you need to fit a solid plug of Celotex directly below the beam and seal with foil tape or foam.