Replies

1. 
   The_Tennis_Court_Builder_...on_t | Oct 07, 2000 04:27am | #1

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   Brad...you can use r-38c which is for cathedral ceilings...install unfaced and then add a layer of foam...say a half inch...tape the joints and your're good to go....If you use track lights instead of recessed would be the best lighting or if you must get airtight Juno cans or similar...And if ya strap the ceiling before drywall it will add another r-2.8 or so...due to the foil and radiant reflectivity...

   near the stream,

   aj

1. 
   David_Wood | Nov 08, 2000 06:16pm | #2

   *Brad, Came across your question today, a month late. I live north of Winnipeg, on Lake Winnipeg where the wind howls all winter. My cathedral ceiling top down is Steel roof/2x4 perlins/2x16 tji's/r40+r12 batts/vapour barrier/2x2 strapping with 1 1/2" polystyrene foam/and finally 5/8 fireboard. I am relying on the 3" gap between the top of the insulation and the bottom of the steel for air circulation. The roof is vented through soffit on all sides but not at the ridge although a vented ridge spacer is available. I put a single turbine just off the ridge for good measure. What I do notice with the steel roof on perlins is that when the steel is cold at night, moist air will condensate on the bottom of the steel(as well as the top). This runs down to the pelins then drips onto the insulation where it seems to evapourate off during the day as the steel heats up in the sun. This seems to be a problem mainly in the spring and fall with cold night temps and moist air. I have heard that putting a steel roof on tar papered OSB is the best and would avoid this problem.

1. 
   tedd | Nov 14, 2000 06:27am | #3

   *Are you guys saying you used steel over FG batts with no sheathing between the two? In other words, your FG batts are exposed to the outside air travelling under the steel?

2. 
   Brad_Buddenberg | Nov 14, 2000 06:27am | #4

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   Should I be worried about condensation build-up in a vaulted roof? If so, what can I do to prevent this? Should a vapor barrier be used? The rafters are 2x12s and the metal roof is attached to 1x6 purlins. I am wondering what is the maximum thickness of insulation that I can use without creating a venting problem?