Latest Discussions : Roofing & Siding

JimChan52

06:14AM | 01/17/03
Member Since: 01/16/03
1 lifetime posts
We are finishing out a new home with metal roofing. The main living area has a vaulted ceiling with 2x6 joists. I have insulated between each joist with R13 batts designed for 2x4's thus leaving an air space between the insulation and the metal roof. We haven't installed the inside of the ceiling yet so I still have inside access to the insulation and roof.

My problem is with recent cold weather, I am seeing water spots on the insulation and a little, very little, dripping on the floor inside the home. Upon inspection, I find the moisture is coming from condensation on the underside of the metal roof. Can any one help me emiminate this problem or at least minimize it?

James Chandler,
Austin Texas

rmurray223

04:44PM | 01/20/03
Member Since: 01/03/03
97 lifetime posts
it is hard to tell the situation from all of this. I am not too familiar with ventilation on a metal roof, I woould suggest getting with a local roofing contractor that specializes in metal roofs to make sure you are getting proper ventilation and if you arent then you need to alter it to what they reccommend, if you dont do it now then major problems can occur.

pgriz

06:46AM | 01/22/03
Member Since: 01/21/03
66 lifetime posts
Prevention of condensation requires three steps:
1) Block any warm, moist area from the living space from entering the attic or roof ventilation area. This is usually done with a vapour barrier.
2) Ensure adequate insulation so that the dewpoint is in the insulation, not in the airspace.
3) Ensure you have adequate ventilation. Air entrance (Usually through the soffits) must be unblocked, the airchannel should be sufficiently large (minimum 2 inches), and the outlet must be situated high on the roof, and be balanced with the inlet to allow convenction.

These three steps are usually adequate to address most of the condensation issues.



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