What is the best way to Prevent condensation forming on the underside of the roofing material? This is an on-going problem for me since living in a townhouse built in 1985. We have cathedral ceiling and a very large void space/attic. In the winter we can see the ice form underneath the roofing material. I'm somewhat handy and want to fix it correctly. Also are recessed lights a bad thing in these areas? They seem to be quite popular in new construction.

I'm having a hard time picturing your attic. Does the cathedral ceiling go up to the roof, or does it just take up part of the attic?

Moisture/ freezing in the attic indicates a venting problem. What vents are installed in the attic? Do you have vapour barrier under your ceiling insulation?

Recessed lights in insulated ceilings can be done, but you need to be careful and use one for specifically rated for insulated ceilings. They also need to be installed inside a vapour proof cover, or be certified by the manufacturer as vapour proof.

Your problem no matter what is Poor Attic venting or not enough insulation or a combantion of both.

Section 1203 of the 2006 IBC requires the total ventilation to be 1/150 of the of the space being vented. 50% of this venting should be by eave/cornice vents, the balance should be at least three feet above the eave/cornice vents. There is an exception that allows you to reduce the amount if ventilation to less - 1/300 if you have a vapor barrier installed on “the warm side”. A minimum of 1” clearance is required between roof sheathing and insulation in all cases

Building Insulation & Ventilation Systems - Inspect, Diagnose, Correct Problems

attic venting

Vent Requirements

BSD-102: Understanding Attic Ventilation —

http://www.southface.org/web/resourc...lings_4pdf.pdf


Insulating facts on R vaule
http://www.xpsa.com/tech/Tech%20Talk...lue%20Roof.pdf


Ice Dams and Attic Condensation - State Farm

Check your local code first to see if there is enough Insulation in on the get go. Also make sure the vapor Barries is against the drywall ( Warm side) of the ceiling.

Without more detailed info can't go much further to see what you are lacking on poor construction practices.

Your problem no matter what is Poor Attic venting or not enough insulation or a combantion of both.

Section 1203 of the 2006 IBC requires the total ventilation to be 1/150 of the of the space being vented. 50% of this venting should be by eave/cornice vents, the balance should be at least three feet above the eave/cornice vents. There is an exception that allows you to reduce the amount if ventilation to less - 1/300 if you have a vapor barrier installed on “the warm side”. A minimum of 1” clearance is required between roof sheathing and insulation in all cases

Building Insulation & Ventilation Systems - Inspect, Diagnose, Correct Problems

attic venting

Vent Requirements

BSD-102: Understanding Attic Ventilation —

http://www.southface.org/web/resourc...lings_4pdf.pdf


Insulating facts on R vaule
http://www.xpsa.com/tech/Tech%20Talk...lue%20Roof.pdf


Ice Dams and Attic Condensation - State Farm

Check your local code first to see if there is enough Insulation in on the get go. Also make sure the vapor Barries is against the drywall ( Warm side) of the ceiling.

Without more detailed info can't go much further to see what you are lacking on poor construction practices.