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Old 11-24-2008, 05:51 PM   #1
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Insulating Cathedral Ceiling


I am currently in the process of installing a cathedral ceiling and had a few questions regarding ventilation and insulation. The house is a ranch (in PA) (roughly 28 x 42) with the typical load bearing wall running down the middle. I am adding a cathedral ceiling to half of the house (roughly 20 ft x 28ft). The roof construction is 2x6" on 16" centers, a gable vent on both sides of the house, a 15ft long ridge vent centered in the middle of the roof, and no soffet vents on either side (I don't believe they could be added due to the construction).

The plan:
Take down the sheetrock on the first floor ceiling, cut and move the 2x6's up the rafters so there is roughly a 4-5' flat where the peak would be. The rest is to be determined. I may have to remove one of the gable vents if it interferes with the height of the 4-5' ceiling I create.

Could I add the 1" foam spacers in the rafter space, add insulation, and add a vent fan in the roof to exhaust the hot air. I understand that ideally there would be soffit vents.

I have read you could have the closed cell foam installed, but I believe that would blow the budget.

Thanks for the help.
Chris

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Old 11-24-2008, 11:30 PM   #2
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Insulating Cathedral Ceiling


Quote:
Originally Posted by cholliha View Post
I am currently in the process of installing a cathedral ceiling and had a few questions regarding ventilation and insulation. The house is a ranch (in PA) (roughly 28 x 42) with the typical load bearing wall running down the middle. I am adding a cathedral ceiling to half of the house (roughly 20 ft x 28ft). The roof construction is 2x6" on 16" centers, a gable vent on both sides of the house, a 15ft long ridge vent centered in the middle of the roof, and no soffet vents on either side (I don't believe they could be added due to the construction).

The plan:
Take down the sheetrock on the first floor ceiling, cut and move the 2x6's up the rafters so there is roughly a 4-5' flat where the peak would be. The rest is to be determined. I may have to remove one of the gable vents if it interferes with the height of the 4-5' ceiling I create.

Could I add the 1" foam spacers in the rafter space, add insulation, and add a vent fan in the roof to exhaust the hot air. I understand that ideally there would be soffit vents.

I have read you could have the closed cell foam installed, but I believe that would blow the budget.

Thanks for the help.
Chris
The gable vents and the optional roof ventilation fan both will not function due to the design.

Remember, each individual rafter bay in a tru full length cathedral/vaulted ceiling is it's own separate ventilation chamber.

Every one of these individual rafter bays needs intake ventilation and exhaust ventilation.

If you absolutely have no clearance of at least a 3" overhang on the soffits to potentially install a 3" wide, continuous under eave soffit intake vent on the entire eave edge perimeter, then, you could create a continuous vent by removing the fascia board and installing a fascia vent product and then re-installing the fascia board, but that comes with the creation of extending out your roof edge.

Were you possibly considering re-doing your shingle roof any time soon? If so, then the Smart Vent by DCI Products would be the best solution. It is a continuous under shingle vent product, tapered to fit smoothly and allow a continuous intake ventilation flowage.

For the exhaust ventilation, a continuous ridge vent, such as the Shingle Vent II, from Air Vent Corporation would be one of the best choices.

Ed

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Old 11-25-2008, 03:27 PM   #3
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Insulating Cathedral Ceiling


Hello Ed,
I was not planning on replacing the shingles at this time. The current shingles are only about 6 yrs old. Although, if this is the only (best) way then I may entertain replacing them.

What I don't want to do is have condensation/mold problems once I go through all the trouble installing the cathedral ceiling and renovating the house. Once I am done I want to be done....

Is the only alternative the closed cell blown in insulation? Are there vents you can install directly in the facia board?

Also, any recommendation on the insulation orientation. I was thinking....
1 - 1 1/2 air gap created by the foam spacer
Faced insulation that will fit in the remaining space
Some type of foam board on the face of the rafters to get closer to the recommended R-value for ceilings in PA.
Then the sheetrock. What type of vapor barrier do I need and where would it be located?
Thanks,
Chris
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Old 11-25-2008, 06:43 PM   #4
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Insulating Cathedral Ceiling


I copy/pasted this information from a similar thread.

Ed



Solutions for no eave overhang intake
There are 3 products that come to mind to address homes with no soffit overhangs to create intake ventilation.

1) Vented drip edge vent by Air Vent Corp.
I've used it, but was too uncomfortable with the 3" vented louvre placement being right over a potential frozen gutter scenario, and I was not comfortable with the 1" gap required to be cut at either the top 1" of the fascia board or at the bottom 1" of the decking.

2) Smart Vent by DCI Products.
I currently have used this on about 60 to 70 homes in the past 4 years. It is an excellent solution, but it costs way too much just for pieces of coroplast glued together to create a tapered profile. I charge enough for it though, and usually find that I am the only contractor who addressed the " other half " of the ventilation scenario.

3) Vented fascia board by Crane Products.
I never used it, but it was created by a fellow roofer, but I believe it is in the $ 15.00 to $ 20.00 per foot range.

4) Create your own vented fascia board with a sub-fascia, then a cobra vent type material, and then an exterior fascia to conceal the product.

I hope these suggestions help out.
I am new to this forum, so get to know me and communicate ideas.

Ed

PS
Everflow is a remake of the old Globe intake vent. Ive never used the other tapered one listed on there web site though, but the concept seems similar to the DCI Smart Vent.
Ed



Venting Eave Edges w/no overhang
Update on the vented fascia. I was way off on my price guesstimate. I looked up "Cellular PVC Lumber" on www.toolbase.org and it states that the initial cost is approximately only $ 3.00 per foot, not my 15-20 per foot guessed before. I haven't ever used it, but that website lists 5 different manufacturers of cellular pvc lumber. Anybody, let me know if it serves the purpose if you wind up using it.

The product from Crane products ltd is called "Perma Choice vented fascia". It states only 6 sq in per lineal foot though. Unless other reasons dictate, I will be sticking with the Smart Vent by DCI.

I truly believe that once I have Properly addressed the "Balanced Ventilation" concept with homeowners, they will see that there is only one Right Way to proceed with the project. Instead of stating, like all other bidders how we are going to do the job right, we actually show them that any other way would result in a poor investment.

Ed



The website for EverFloVent.com
The Website for Ever Flo Vent is ever flo vent .com not Ever Flow

There are spec sheets and literature on the Inhaller.
Great Product
Hope this Helps

Stevieg


I agree that the vented drip edge by Air Vent is no good.

I am considering the use of the Smart Vent product. But I am concerned that when the gutter is full of snow or ice, Smart Vent wouldn't function. The vented fascia board by Crane Products, Inhaler Vent from Ever-Flo Vent, and a custom fascia board with Cobra Vent type material would all continue to function. These products would never get blocked by accumulated snow or ice.

I would like to hear about first hand experiences with Smart Vent when the intake opening gets covered with snow or ice.

By the way, GAF makes a product called Cobra Fascia Vent. The installation instructions for the fascia vent can be found at www.gaf.com/Content/Documents/20562.pdf . This seems like what you referred to under item 4.

atulc
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