Loft conversion - cavity between new loft floor and old ceiling?

[-crashd]

We're coming to the end of a loft conversion in a bungalow (thankfully!) and looking at our plans for an extension. The staircase is "in" but new stud walls not yet made or plasterboarded. There's a gap between the existing ceiling (which is of lathe and plaster construction) and the floor of the extension (which is suspended insulation under TNG etc..). I wanted wanted to ensure this gap is well insulated internally (so where it meets the staircase) as well as externally (which I assume will be stud / block work / guttering etc...). I wondered if anyone had any advice that I could put to my builder to ensure this is the case, obviously they're going to have an opinion too

Edited January 5, 2023 by -crashd

[Redbeard]

Hello.

 

You say "There's a gap between the existing ceiling (which is of lathe and plaster construction) and the floor of the extension (which is suspended insulation under TNG etc..). I wanted wanted to ensure this gap is well insulated internally (so where it meets the staircase) as well as externally (which I assume will be stud / block work / guttering etc...). "

 

I don't quite understand that explanation, because you refer to 'plans for an extension' (which implies it is not there yet) but you also refer to  "a gap between the existing ceiling (which is of lathe and plaster construction) and the floor *of the extension*".  I am guessing that when you say extension in the second example you actually mean the loft conversion. (Maybe...)

 

Can you enlighten me? 

 

Pictures/drawings would be good.

 

Apologies if I am just being obtuse.

 

[-crashd]

You're right, I meant loft conversion, not extension. Apologies!