Roof Ventilation / vapour barrier

[MFC_1980]

Hello.

A garage conversion to a kitchen (22.5' single storey lean to roof) which currently has an un-insulated roof, walls and floor with a traditional non breathable sarking felt underlay below the tiles.

My query is with the roof. If i provide c250mm of insulation at ceiling level, I will also have to provide ventilation above.

Question 1 - Is this avoidable with the use of vapour barriers at ceiling level? or any other way?

Question 2 - If it is unavoidable, how is ventilation provided as an after thought i.e. on a finished structure? is it just a case of ensuring there is space at the eaves and changing the fasica/soffit boards and installing vents?

Any help on this would be great!

Thanks!

 

[noseall]

vent tile terminals are an option.

using a vapour check plasterboard i.e. duplex or foil backed can help reduce but not entirely eliminate moisture.

 

[MFC_1980]

Thanks for the response.

so realistically it would be best to use vapour barrier at ceiling position as well as vent tile terminals/eaves vents.

 

[noseall]

Thanks for the response.

so realistically it would be best to use vapour barrier at ceiling position as well as vent tile terminals/eaves vents.

yup.