Steel Box Profile Roof 'Fillers'

[mikkymo]

I’m building a garage which has a box profile steel roof. The roof came supplied with foam fillers which go at the ridge (underneath the ridge cap) and at the eaves, but the supplier of the roof mentioned I could leave the eaves fillers out ‘to keep condensation down’.

The garage is being fully lined with a wooden stud wall, insulation, vapour barrier and plasterboard, primarily to keep noise down. Am I right in thinking all the moisture is contained within the plasterboarded space and with the insulation there, I have a ‘cold roof’ so I can put all the fillers in to give me the best noise insulation? Should I add a vent in the gable end to keep air flowing through the attic space or is that overkill?

Mikky

 

[catlad]

Box profile roof sheets = condensation in my experience, if you don't want condensation issues then you can buy anti condensation roof sheets.

 

[mikkymo]

Surely water vapour is going to come from 2 places though - outside the garage (from rain, mist, dew, etc.) but primarily from inside the garage from wet cars, people breathing/sweating, etc.

If I deal with the inside by plasterboarding, vapour barrier and insulation, I just need to worry about the outside. Eaves fillers = sealed roof space = no water vapour = no condensation?

I think I'll install it and leave myself an attic 'hatch'. I'll check it and see how it goes.

Cheers!

 

[theprinceofdarkness]

I believe that your roof will drip condensation in all cases. This is because in the autumn and spring, during the day the sun will raise the roof temperature a lot, and during the night the temperatures will fall rapidly and the excess moisture will condense out. Now if you had a fan blowing the hot air out and replacing it with cold dry air it might be OK. The problem is that you need good ventilation to cure the problem and you just will not get it. Having had two garages with thin roofs and no eave or ridge filler foam, you actually get rain and you can hear the drip drip of the water of the girders.
Frank