Condensation in roof space

[marko333]

Hi all,

Should a roof space (attic) be ventilated in a commercial single storey building (maximum/minimum design ambient temps of 36 / 4 oC) containinng air conditioning ductwork if both the ceiling and roof areas are well insulated and provided with moisture barriers.

Is it possible that condensation will occur during winter months and will heat loss from air conditioning ductwork be worse if the area is not ventilated but sealed?

thankyou.

 

[MarauderX]

I would treat it similar to a home attic. If the attic is not meant to be occupied (for storage), with insulation above the space below, then the attic should have a minimal airflow through it. No need for a fan, just a vent or two to the outside to let the air moisture and temperature to stabilize and prevent condensation.
If, however, the attic is to be conditioned, then the roof itself should be designed and insulated with a moisture barrier to prevent condensation.

 

[imok2]

There is no need to vent, if you do you may be bringing in hi humidity air from outside

 

[quark]

No problems provided your duct insulation and under duct insulation is intact. Heat loss from the duct work would be worse if you provide ventilation to the attic (by the laws of convection). I would go with imok2's suggestion of not going for a vent but there is nothing wrong if you make a provision and close it off (if, by any chance, you have to crawl in the attic, this will give you some fresh air) .

Regards,


Eng-Tips.com : Solving your problems before you get them.

 

[ercanbaser]

Proper insulation and vapor barrier can solve attic condensation problem but depending on humidity rate there may be a risk of condensation if the water vapor that is drift up into attic from building , is not exhausted. It can condense upon the cold roof frame members. Passive ventilation (turbine vent) can help in this sitiation.

This link may be helpful,

http://www.askthebuilder.com/Ventilation.shtml

regards,
Ercan