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kgagnon7 10-14-2012 07:37 PM

The roof above my ceiling has a very small space that has limited room for insulation to get enough r value (r50) as it is an attic space. It currently only has about (r12). The slope starts at front of house and starts to go up than it slopes up into a crawl space and than it becomes a sloped ceiling in the bedroom. Because of the lack of space in the attic space above living room I know I eventually need to put valleys in there and maybe fill in with insulation right to the valleys, but I can't get to that until I redo my roof as it being old insulation it would be too messy for inside the home as we live in the home. I am thinking of doing this when the roof is opened up to put new sheeting down and get rid of the old planks.

Now to the question I am wondering if there is any issues with putting RX energy shield sheeting on my living room ceiling about 3 inch for (r21). I have the room for it as I have a high ceiling. I would just put drywall over top of it afterwards. I figure this would certainly help with my heat loss I am getting from this ceiling. Also do I put a vapour over top the rx sheeting? I am thinking not, but I honestly don't know as the ceiling currently has no vapour barrier.

Thanks for your time. Note I did search the forum first before posting this so I apologize if this has been mentioned before and I just couldn't find it in the search.


ToolSeeker 10-15-2012 07:53 AM

If i'm reading this right (and I may not be) would blown in or foam achieve what you are looking for. I'm not an insulation guy though so someone else may have a better idea.

kgagnon7 10-15-2012 08:00 AM

Spray foam not gonna work right now cause of access. I can consider it when roof gets redone. Just looking for solution without opening up anything right now. Trying to put this in another forum but can't do it on my phone.

kgagnon7 10-15-2012 08:03 AM

Hope someone has an answer.

Gary in WA 10-15-2012 10:37 PM

It sounds like the ceiling is vented, extending upstairs through a sloped ceiling? Is this ceiling a (1) cathedral or (2) just a short attic, (3) is it vented?

Where are you located?


kgagnon7 10-15-2012 11:03 PM

5 Attachment(s)
Not sure how to answer your cathedral questions, but here are some photos to help make it more clear.

The portion of the roof you see that small flat vent. That is roof above living room the ceiling that I'm looking to insulate with the RX sheeting. That roof slopes up gradually. Half of the living room ceiling is a portion of the slope that has less than a foot of space for insulating. Another 3' is a crawl space and the rest of the ceiling is floor for upstairs bedroom that has a half wall separating attic crawl space from bedroom. You can see in my drawing on the left side of that picture how that looks. Also in the first photo you can see the space that goes above the living room that is not much room for insulation. There is insulation in there just about an r12 or r10. The slopes coming out of this crawl space has valleys to peak.

Note I'm just wanting to know if there is any issues with using the RX sheeting on ceiling for that extra r value. As for venting it only has that flat vent. The slope roof portion of the bedroom has valleys, but the house doesn't have any overhang at front so no flow of air to push the air up those valleys. This is something I look to work on when I redo the roof. For now it's just a matter of making my winters warmer in the living room and reducing some ice on roof.

This is a very messed up roof that needs a lot of work. More valleys, vents, and insulation needed that I know.

Thanks for your time.


kgagnon7 10-16-2012 06:08 AM

I live in Northern Ontario Canada very cold winters hence why the r50 recommended for attic insulation.

Gary in WA 10-18-2012 10:39 PM

The pictures help immensely. You need wood rafters to support the OSB roof sheathing. What is existing (unless the rafters are under the OSB) is dangerous. Your thermal barrier should go across the flat ceiling (the one with the fiberglass batts facing up rather than down toward the warm room side) under tha beam, across the floor to stop and go up the knee wall, extending up the sloped ceiling across the top attic ceiling. Or, insulate the rafters: fig.4; Stop the air from going under the knee wall. Housewrap on the attic side of the knee wall insulation to prevent wind-washing.

Far as the ff XPS on the ceiling, it will work for wintertime. Long as it's air-tight (seams taped/canned foam) and covered with drywall for the thermal (fire) barrier, check with your local AHJ. Be sure to remove the paper facing on the batts, simply slashing them will do nothing. With that much foam, the drywall fasteners may be a problem...

It would be similar to SPF, then venting above that in a cathedral ceiling; pp 70;


kgagnon7 10-30-2012 12:02 PM

Thanks Gary a lot of help. I'm a bit confused but will read it till I get it.

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