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Old 06-08-2008, 04:28 PM   #1
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Cathedral Ceiling Insulation/Reflective Roof Coatings

I recently bought ranch home in Atlanta that was built in 1955. It has cathedral ceilings, and now that it is summer I have realized that it has little to know roof insulation. The ceilings are warm to the touch, and the house is hot. Because of the ceilings, we have no attic space. Is there a way to add insulation without adding a drop ceiling? Has anyone had experience with reflective roof coatings? The previous owner re-did the roof about 2 years ago. The roof currently has dark asphalt shingles.


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Old 06-08-2008, 05:14 PM   #2
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The most opportune time to have addressed the problem for the lowest investment fee, would have been during the roof replacement process.

Ensuring that the insulation has an air space on to of a minimum of 1 1/2 inches and providing continuous Intake Ventilation and continuous Ridge Venting Exhaust Ventilation could have easily been done at that time.

Now, you may not even be able to determine if there is any air space for ventilation flowage in there at all, without cutting open the roof.

You could at least have a continuous Baffled Ridge Vent installed at minimal cost, an I would suggest the Shingle Vent II by Air Vent Corporation or the Snow Country Ridge Vent by GAF. This will help out a lot if you do not already have a ridge vent in place, but still will not be at optimal efficiency if there is no continuous Intake Ventilation and air flow above the insulation.

I do not know of good quality shingle coating products that look aesthetically pleasing and provide the reflective qualities required.

I will check into it for you though.



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Old 06-08-2008, 05:32 PM   #3
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Hi Ed! Thanks for your quick reply. I do not believe that there is any ventilation space at all. Is there anything else that can be done, or am I SOL?
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Old 06-18-2008, 04:31 PM   #4
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cathedral ceilings are always a problem, and not because they are a falwed design but because mo-mos usually build them. Usually the problem is that the cavity between the ceiling and the roof is packed with insulation and air flow is blocked. This might even be the case since that cavity will super heat. So you may have too much insulation rather than too little.

I'd recommend removing a little bit of your ceiling or exterior over hang and taking a peek inside. A well balanced ventilation system would include intake and exhaust. For proper ventilation of a cathedral ceiling you need to treat each rafter like it's own zone. The ventilation method can be very cumbersome, or sometimes simple. If it's a ridge vent, and have a CONTINUOUS soffit vent, you're set, assuming the flow is not blocked. If there are not continuous ridge or soffit vents horizontal holes must be drilled in the center of the rafters, about 1" wide, to allow for horizontal air flow and transfer air from one rafter cavity to the next. Keep in mind notching the rafters or placing the holes anywhere off center will comprimise the structure and load bearing of your rafters.

Another option is a ventilated nail base as manufactured by Atlas or Hunter. Basically you are installing a piece of rigid insulation which has been laminated to a piece of plywood or OSB witha 1" air gap between the two.

Another option is to create a false roof deck over your existing roof deck. This is done by installing 2x3's horizontally as to raise the roof surface 1 1/2", then isntalling all new 1/2" 4 ply CDX plywood over the dummy rafters and install a completely new roof over the new plywood.

Both methods I have mentioned we have done several times and both are costly, but if you care about your biggest investment, both are worth doing for the longevity of your home.
The information found in this post is not to be considered legal advice. The author of this post takes no responsibility for any losses that occur. Use at your own risk.
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