Question:

I have a story and a half with a tin roof and have reinsulated the house completely. The roof has R20 on the down slope and the top section has R40, it is all vapour barriered (Super Six)with two inch air space in all rafter spaces. I seem to be getting moisture running down the tin (inside) and leaking into the new walls that are also R20 with vapour barrier. The house isn't drywalled yet as we are slowly completing the reno's ourselves. The roof has a complete end to end ridge cap, shouldn't that be adaquate for ventilation? What else could be causing the excessive moisture problem? I am now starting to see mold forming on the inside of the new aspenite installed on all exterior walls...HELP...

Answer:

Hello, This is the reason that the roof should be sheated with plywood and a seperation sheet such as tar paper or ice and water shield opposed to being strapped only. No matter how well insulated the house is there will always be heat loss. This heat loss will cause the attic space to be slightly warmer than the outside temperature causing the metal to sweat on the warmer side. This metal will sweat everyday with the temperature change. In your question you mentioned you had "ridge cap" from end to end. I hope you were referring to "ridge vent". If not, replace that ridge cap with ridge vent ASAP. Matt Churchill CP Roofing & Sheet Metal of Ottawa Ltd. 613-821-4455

Answered By: Ormand & Matt Churchill

More Questions & Answers ...