roof vents

iv recently reroofed a lean too roof with 3/4 ply and had a company felt it for me my question is

i am starting to put up the ceiling inside now and was wondering do i need to put some kind of roof vent in i am using 4" kingspan in between in ceiling joist and there will be a gap from the top of the kingspan to the roof of about 3" does it need to breath or will it be ok

Had you asked this question before ply and felting the roof, you could have fitted a less expensive 'warm deck' roof.

Now in order to avoid retro-venting, you should fill the entire void with kingspan.

Incidentally, kingspan supply a ply bonded insulation board specifically for warm deck roofs.

yr it was me before but did nt sak the same question i spoke to a experienced builder today and he said i dont need to put vents in if i use 4" insulation and use foiled back plaster board it ll be fine he has more than 30 yrs of building behind so would any one agree with that advice