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# "fake" cathedreal

#1
11-08-03, 05:42 AM
controlpeddler
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Posts: n/a
"fake" cathedreal

Just bought new house and have always had problems in my sons room with heat and now with cool weather it seems cold. His room is in the front of the house facing south- it has a large half window at the top of the main window that doesn't have a blind or window covering. His ceiling is cathedreal, however his ceiling doesn't make up the roof- there is space in the attic between his ceiling and the roof. probably six feet to the roof. Here is my question- I presently have a good 12" of blown insulation on top of his room and the sides of the ceiling and I would to put some batted insulation on top of that, but I am concerned on how to accomplish this. Any help?

#2
11-08-03, 08:54 AM
Member
Join Date: Nov 2003
Location: NE INDIANA
Posts: 111
While looking for solutions to my own cathedral ceiling situation, I found on "Owens-Cornings" website products that are designed for exactly what you are asking about. The home centers (Lowes, Home Depot, etc.) all carry unfaced fiberglass batts for the same purpose... overlaying present inadequate insulation. Hope that helps...

#3
11-11-03, 11:16 AM
Member
Join Date: Apr 2002
Location: Boulder, CO
Posts: 125
Tackle the biggest heat losses first, which might not be in your attic. To give an example, assume that your son's ceiling is 250 sq ft (a good-sized cathedral ceiling), and that the large window is 12 sq ft. Put actual numbers for your house in when you do it, of course. The 12" of blown-in insulation is worth R-38, the window about R-1 if it's single pane.

The heat loss through a surface is
Q = Area * (Tinside - Toutside) / R-value

If it's 65F inside and 20F outside, then
Qceiling = 296 BTU/hr
Qwindow = 540 BTU/hr

1) You can add R-25 attic batts for a total R-63, saving 118 BTU/hr. I like John's-Manville Comfort-Therm from HD and Lowe's since it's less itchy. Make sure it is rated for attic use (vapor permeable).

2) Cover the window with a Hunter-Douglas Duette honeycomb insulating window shade, which adds R-2. They come custom made to the window shape (even semi-circles, etc). You'll save 360 BTU/hr!

In this case, improving the window gives 3x the benefit of more attic insulation, and it's a lot more pleasant to install!

3) If the window is double-paned, you'll save about 135 BTU/hr with the shade, which is still more than the ceiling.

Weatherstripping and sealing air leaks at electrical outlets could also give you more improvement than attic batts. If you've done these and it's still too cold, then turn your attention to the attic.

#4
12-18-03, 11:14 AM
tenaciousd
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Posts: n/a
Got Blown-in => put in more or put in Fiberglass?

I live in South Carolina in an old and very shaded neighborhood and am installing additional insulation, as controlpeddler is/was. I'm curious whether you think it's beneficial to remove the old blown-in insulation, add a vapor barrier, then place new fiberglass on top, OR would placing fiberglass batts over the existing blown-in (w/o a barrier) be appropriate? I'm fighting a moisture problem in the house and figure any moisture inhibitor is good.

My home is about 50 years old and unfortunately has no in-wall insulation, so I'm stuck with adding attic insulation and, short-term, window caulking. Long term I think I am going to replace the 17 windows with current, energy-efficient windows.

Do you think it's beneficial to also add floor insulation? My crawl space is truly a crawlspace, yet I'd LOVE to wake up to a not-so-cold floor.

#5
12-20-03, 08:04 AM
Member
Join Date: Mar 2003
Location: USA
Posts: 2,425
tenaciousd,

I'd leave the old blow-in in place, my felling with attics, you can never have too much insulation, besides, it can be quite a chore to remove the old stuff.

If you have not got any insulation in the floor, I'd consider addiing it there, additions here in the mid-west also sometimes have a layer of house wrap stapled under the floor joists.

What is the exterior of the home?, wood siding, brick, stucco? Replacing old inefficient wiindows with modern energy efficient windows will make a big difference in the comfort level of your home, adding insulation to the walls will also help alot, particularly with A/C costs in your area I'd think. You can also add blow-in insulation in the walls by cutting slots at the top of the wall between the studs, blow-in your insulation and patch the plugs.

Good luck & happy holidays!

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