06:17AM | 10/07/01
Member Since: 10/06/01
1 lifetime posts
I have an attic area similar to the second picture at - the gabled wall attic.

Currently there is only insulation in one of the flat parts on the side of the house. The other flat and the cathedral portions are not insulated.

Essentially I figure on the flat parts of the roof I need to install about 4 soffit vents per side - or a soffit plug for each section between rafters and then put a baffle in each section to create adequate air flow, cut ventilation holes in the middle "knee wall??" to keep the air flowing and then put baffles all the way up the cathedral ceiling portion to the ridge vent at the top.

Now comes the insulation, I live in the north suburbs of Chicago and from what I can tell the recommendation for attics is about R-49. In the flat part I think all I need to do is staple the insulation in-between the rafters. When it comes to the cathedral part is when I really run into trouble. The "rafter joists??" - the wood connected to the actual roof is only 3 1/2" wide. When I went to look at insulation, R-30 is already 10" thick and I still need to add another R-19. When I looked at what would fit on the 3 1/2" "joists" I would only get R-13 and that is without baffles.

Additionally 1/3 to 1/2 of the attic is finished but there is the 3 1/2" gap between the drywall portion of the room and the "roof" - I'm planning on blowing some insulation in but I will only get an R-13 rating.

The insulation I was looking at is paper-backed/faced - planning on using that as the vapor barrier (facing down).


How do I insulate the cathedral part correctly to achieve the best insulation?

In insulating the flat part do I need to lay down something to hold the insulation up so I does not actually rest on the ceiling?

Would the paper-backed insulation create a sufficient vapor barrier or do I need something additional - or should I just use something different and go with the non-paper backed insulation?

When I blow insulation into the 3 ½” gap do I need to put a vapor barrier on the down side – if so how would you recommend getting it in the gap so it does not rest on the dry wall or does it matter?

How big of a difference does an R-49 to R-30 to R-13 make?

In this case would anything really be better than nothing?



08:31PM | 10/08/01
Member Since: 09/23/01
242 lifetime posts
Wow, lotta stuff to cover, to start the highet the R value the more insulating value. So R-30 is over twice the value of R-13(typical 2x4 wall). Soffit vents and RIDGE vents are very important, and you should have at least 4sq in of free air per bay, with a 1" air space between roof sheathing and insulation. For the cathedral portion I would suggest ridged foam board, 3" thick is R-25. On the flat portion just roll out unfaced bats, you do not need any support other than the drywall. I wouldnt worry about a vapor barrier in the ceiling, only the walls. Hope this helps.

Jay J

09:02AM | 10/09/01
Member Since: 10/26/00
782 lifetime posts
Absolutely! Make sure the ceiling is vented!

Otherwise, later on, you'll be writing to us wondering why your cathedral is showing signs of mold/mildew.

Consider a skylight too, one that can be opened and closed via a motor. (Velux, for one, makes them ...)

My best to ya and hope this helps.

Jay J -Moderator

PS: God Bless America!



Post a reply as Anonymous

Photo must be in JPG, GIF or PNG format and less than 5MB.


type the code from the image


Post_new_button or Login_button

Making this trio of storage totes is simpler than you might think. Gold screw bolts and spray adhesive hold the fabric cov... Built on a rocky island in the Drina River, near the town of Bajina Basta, Serbia, this wooden house was cobbled together ... Large steel-framed windows flood the interior of this remodeled Michigan barn with daylight. The owners hired Northworks A... Edging formed with upside-down wine bottles is a refreshing change. Cleverly and artistically involving recycled materials... A Washington State couple called on BC&J Architects to transform their 400-square-foot boathouse into a hub for family bea... Similar to the elevated utensil concept, hanging your pots and pans from a ceiling-mounted rack keeps them nearby and easy... Few projects are more fun than upcycling a vintage piece in a surprising way. Outfitted with a sink and a delicately tiled... The thyme growing between these stepping stones adds a heady fragrance to strolls along this lush, low-maintenance garden ... Decoupage is an easy way to add any paper design to your switch plate, whether it is wallpaper, scrapbook paper, book page... Twine lanterns add pops of crafty—but sophisticated—flair to any outdoor setting. Wrap glue-soaked twine around a balloon ... When securely fastened to a tree or the ceiling of a porch, a pallet and some cushioning make the ideal place to lounge. V... Reluctant to throw away any of those unidentified keys in your junk drawer? Hang them from a few chains attached to a simp... A stripped-down model, sans screened porch, starts out at $79,000. Add the porch, a heated floor for the bath, and all the... Salvaged boards in varying widths and colors make up the dramatic accent wall in this attic space. The high-gloss white of... This garden shed has been decked out to the nines. Designer Orla Kiely created the intimate home for a flower trade show, ...
Newsletter_icon Google_plus Facebook Twitter Pinterest Youtube Rss_icon