Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Insulation

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 06-20-2013, 05:16 PM   #1
Newbie
 
Join Date: Jun 2013
Posts: 4
Share |
Default

Re: Unvented cathedral ceilings


I live in the Pacific NW. We have a 3:12 pitch roof with archies, installed about 9 years ago. The roof has been a headache ever since with numerous leaks. The roofing company seems ready to replace the roof and install an I&W membrane over all the sheathing before putting down the shingles. The issue is that several roofs have cathedral ceilings and no venting. They will not offer us a warranty on the new roof without the vents.

The older cathedral ceilings (1928 house) have an insulation-filled cavity (no room for airflow) between the sheathing and the ceiling (2x4 joists). The other cathedral ceiling is newer (1970's addition) and the joists are 2x6 or 2x8, also filled with insulation and no room for airflow. Almost everyone I talk to says that we have to find a way to vent these ceilings, though I have run across some evidence to the counter (on this site, for example). After all, there are many older homes, still standing, that have never been vented.

Solutions presented to me range from raising the roof 1" to 2" inches, to lowering the ceilings, to compressing the insulation an inch, to installing baffles. We have not, to my knowledge, had issues with condensation, but will only know after the sheathing comes up.

Curious what sort of feedback I might get here?

redpine17 is offline   Reply With Quote
Old 06-20-2013, 05:24 PM   #2
Member
 
Join Date: Nov 2011
Location: Hartfield VA
Posts: 25,541
Default

Re: Unvented cathedral ceilings


Consider SIP roofing panels.
Google it.

__________________
When posting in forums, letting us know your location will help others give better feedback/advice/solutions to your questions
joecaption is online now   Reply With Quote
Old 07-24-2013, 01:54 PM   #3
Newbie
 
Join Date: Jun 2013
Posts: 4
Default

Re: Unvented cathedral ceilings


Joe,

Failed to get back to you on SIP roofing panels. Very cool idea. Amazing R values! Unfortunately, for me personally, way too expensive right now.
redpine17 is offline   Reply With Quote
Old 07-26-2013, 10:51 PM   #4
Registered User
 
Join Date: Mar 2009
Posts: 9,968
Default

Re: Unvented cathedral ceilings


Find your Zone;http://publicecodes.cyberregs.com/ic..._11_par002.htm

Then add the rigid to prevent condensation; http://www.buildingscience.com/docum...rchterm=attic+

Good read; http://www.buildingscience.com/docum...r-all-climates

Gary
__________________
If any ads are present in my answer above, I do not condone/support/use the product or services listed, they are there against my permission.
Gary in WA is offline   Reply With Quote
Old 07-29-2013, 12:27 PM   #5
Newbie
 
Join Date: Jun 2013
Posts: 4
Default

Re: Unvented cathedral ceilings


Gary,

This was a great reply. I did not know about the option of a "hot roof" or an unvented attic assembly. I was just assuming that vents would absolutely be necessary.

The zone I'm in is 4C. I haven't had a chance to look into it yet, but one of my cathedral ceilings is only 3.5" between drywall and roof sheathing, i.e., a 2x4"

Nevertheless it might be the way to go even if I have to sacrifice some R-value.

Thanks again for posting!
redpine17 is offline   Reply With Quote
Old 07-29-2013, 12:38 PM   #6
Member
 
Join Date: Jun 2011
Location: Atlantic Canada
Posts: 377
Default

Re: Unvented cathedral ceilings


I'd consider a ventilated nail base, such as http://www.atlasroofing.com/tabbed.php?section_url=51
These can also be made onsite with board insulation, strapping, and OSB. You could probably skip the OSB if you want to install metal roofing.

Personally I think ventilation is a best practice kind of thing, and hot roofs are favoured because they are a simpler (aka cheaper) fix. I think they are better on paper than in the real world, as a system with ventilation can deal with moisture/heat issues much better.
shazapple is offline   Reply With Quote
Old 07-29-2013, 12:55 PM   #7
Newbie
 
Join Date: Jun 2013
Posts: 4
Default

Re: Unvented cathedral ceilings


Thanks for posting. So this option would also necessitate soffit and ridge/roof vents, no?

What do you think of this:


“For the most part, the focus of codes, researchers, designers, and builders on roof ventilation is misplaced. Instead, the focus should be on building an airtight ceiling, which is far more important than roof ventilation in all climates and all seasons. ... Once this is accomplished, roof ventilation becomes pretty much a nonissue.” ~building scientist Bill Rose

A related article by him:
http://www.fpl.fs.fed.us/documnts/pdf1999/tenwo99a.pdf
redpine17 is offline   Reply With Quote
Old 08-05-2013, 11:50 AM   #8
Registered User
 
Join Date: Mar 2009
Posts: 9,968
Default

Re: Unvented cathedral ceilings


There are hundreds of unvented roofs here, locally, still standing, lol. I have used that link here before, it depends on local weather, air-sealing the attic, interior RH, diffusion (slightly), insulation, etc. Other links; (up-dated version) http://www.fpl.fs.fed.us/documnts/pdf2002/rose02a.pdf

Good for moisture; http://www.professionalroofing.net/a...2/feature2.asp

Gary

__________________
If any ads are present in my answer above, I do not condone/support/use the product or services listed, they are there against my permission.
Gary in WA is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
insulating conundrum 2X8 Cathedral Ceilings rudy2262 Insulation 2 04-08-2013 08:23 PM
Insulating/Vapor barrier/Venting a 2/12 pitch Shed Roof with Cathedral Ceilings cmlarsen Insulation 6 12-21-2011 09:50 PM
What's the RIGHT WAY to build sheet metal roof and cathedral ceilings? Mustang Gregg Building & Construction 6 12-16-2011 11:01 PM
Ideas for walls with cathedral ceilings Lamenz Interior Decorating 2 10-04-2011 05:36 PM
Guidance for Insulating Slanted Ceilings - Cathedral Ceilings mdlorenz Roofing/Siding 17 09-02-2009 10:05 AM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.