Attic insulation - cold bridge

LaLaLamb

I have a single story extension with a pitched roof on a two story house. Got two quotes for filling the cavity walls of the extension (main house is solid block). I also asked about insulating the attic of the extension.

First guy said not to insulate the attic as it would cause a cold bridge (I guess where the extension ceiling meets the main house external wall?). Second guy said there's no issue with a cold bridge. He did say we should put vents in the roof but I don't know how that addresses a potential cold bridge issue. Any advice?

Thanks

MicktheMan

Who are these "guys"?

Not insulating an attic to avoid thermal bridging is the biggest load of bull I've heard in a while.

Roof ventilation has nothing to do with thermal bridging so perhaps the 2nd "guy" noticed an actual issue with the roof ventilation and you conflated what he said with thermal bridging?

LaLaLamb

Thanks MicktheMan, they are from two companies that install insulation. My other half may have misunderstood the vent point, but good to know we don't need to worry about a cold bridge. Thanks again.

Yellow_Fern

I don't understand what he means. Lean to single floor extensions often have cold bridges as the external wall runs inside. It can dealt with.

Mellor

Adding insulation can never cause a cold bridge. If the bridge exists, it exists