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Heat loss where ceilings/walls meet

Posted by amyspaetzle (My Page) on
Tue, Feb 16, 10 at 12:33

After a lengthy infrared heat loss analysis of our home, it looks like we have significant heat loss where the exterior walls meet the ceilings.
Up in the attic we have baffles leading out to the perforated vinyl soffits. R-19 fiberglass batts and cellulose are pushed under the baffles and as far forward as we could get them. I believe I saw the gap when installing the fiberglass but couldn't reach that far and thought it would be more accessible from the outside, which it's not. Ancient fiberglass batts in the outside walls. What's the best way to reduce the heat loss? Is it fixable from the outside by adding insulation near the top of every stud cavity, or is it something that should be tackled from the attic?No problems with icicles and the snow pack stays consistent on the roof. No major heat loss through the ceilings..but you sure can feel the cold air spilling down the wall. Thanks in advance for any input.


Follow-Up Postings:

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RE: Heat loss where ceilings/walls meet

Remove the insulation you've stuffed under the baffles. Those baffles are there for the express purpose of keeping a passage for air flow into the attic, mainly to keep ice dams from forming at your eaves.

Whoever did the heat loss analysis should have explained that to you.

More insulation is not the answer; sealing all leaks with caulking and foam is.


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RE: Heat loss where ceilings/walls meet

agreed.
unless your walls are balloon framed (which would be without a top or sole plate) the leakage comes from
behind the ceiling molding. if you were to remove the
molding you would see the gap.
in new homes walls to ceiling sheetrock is taped and sealed
before moldings go up..as part of air tight drywall approach.
what you are 'seeing' on the IR camera is air infiltration.
IR & blower doors should be used together .. or you get
misinformation,
your auditor (?) should have explained things better to you
and given you solutions to the issues.

so what can you do? remove moldings caulk and reinstall.
or caulk top of molding to ceiling, and bottom of molding
to wall.

best of luck.


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RE: Heat loss where ceilings/walls meet

I suspect the old insulation in the walls settled down, leaving a gap of a couple inches or more in each stud cavity. Put your hand on the wall near the top to test, or open up a couple spots and take a look. I don't know the best way to tackle that, but I'd look into having spray foam pros make holes near the ceiling (each cavity) and add spray foam.


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RE: Heat loss where ceilings/walls meet

I've always found worthy and energy_rater_la to be very reliable in their advice. In fact, we recently pulled the baseboards off to have our floors refinished and the difference was noticeable. We had towels along the edges of the room for awhile! We had the same IR and blower door test done with the same results along the tops (and bottoms) of our walls, but we don't have any insulation in the walls.

Since you also say you have old insulation in the walls my completely uninformed guess is that could have settled down as homebound says as well. So I guess I'm agreeing with everyone above ;)


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RE: Heat loss where ceilings/walls meet

Thank you all for the great advice. I did pull the fiberglass batts away from the soffit edges last night. I still cannot access where the ceiling and walls meet. I can see the gap from the attic but can't crawl far enough back. The depth from the attic floor to the roof at that point is only 9 inches so even if I could get back there, I couldn't get a tube of caulk or foam back there.
Any chance I can tackle this project from the inside? I don't have ceiling molding. Would it make sense to cut the joint where the ceiling and walls meet, foam or caulk the joint, and then install crown molding to hide it?
Good call on the slipping insulation. I drilled a few holes about a foot down from the ceiling and it appears the insulation has sagged or was cut short to begin with.


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RE: Heat loss where ceilings/walls meet

Professionally applied closed-cell spray foam at the top plate from the attic side would appear to be the best way to seal the air gaps. Blowing in fibrous insulation at the tops of each wall cavity would take care of the settling insulation problem. Of course, the walls are still probably way under current energy-savings recommendations.

Budget and payback period are the biggest issues in retrofitting old homes. You'll have to decide what's it worth to you.



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RE: Heat loss where ceilings/walls meet

If the bats were lying on the ceiling they should be fine.

You do not want the bats obstructing the air flow from the soffits into the baffles on the roof deck, but you want them as far out as the outside of the wall or end of the baffle (whichever is further in from the eaves).

A long wooden pusher can be used to push bat insulation into the eaves.

A painters pole and an acid brush work well.
The brush can grab the insulation an help position it.


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RE: Heat loss where ceilings/walls meet

let's back up..
what other areas of concern did the scan pinpoint??
I blower door test and find that there are usually several areas that need addressing. focusing on one area..unless it is a huge leakage is a mistake.

thermal barriers (continous insulation) are important,
but there are limits imo as to what pays back and
effects the comfort of the house.

air barriers (again imo) are the more important of the two.
air barriers stop the air movement into the conditioned space. even with good solid insulation if air moves through it..it loses its R-value.

first seal the air barrier ...then upgrade the insulation barrier.
some thermal barrier repairs such as small areas of walls
are not cost effective.
I know of few companies that would
fill the top 6" of walls without other work either at the same house, or nearby.
Foam insulators however may be more open to sealing the top plates from the attic.Foam sealing the soffits/eaves at the roof wall junction and approx 1 to 1 1/2 feet onto the attic floor, batts moved out of the way and placed back after foam is complete. Lots of labor. This would create an air tight attic, so be sure that this is what you would want.
Oh and we use open cell foam, less R-value, but in some cases it is more the air sealing quality that is the goal.
open cell allows moisture to move through it, where closed cell does not.

before investing in foam you should see what is recommended for your area, and investigat what making your
attic unvented would do to the dynamics of your house.

share more info with us and your general location.
why did you have the IR scan?
what else did it show?
any suggestions from auditor?

best of luck


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RE: Heat loss where ceilings/walls meet

According to Building Science Corp., either closed cell or open cell foam are acceptable for sealing rims. I figure if you're spraying, you might as well get the highest R-Value you can in a constricted area.

Shoving in fiberglass over holes mostly filters airflow. (The only time I use it that way is when I've got construction heaters running and am trying to temporarily seal gaps.)


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RE: Heat loss where ceilings/walls meet

energy_rater_la
Thank you so much for your insight. Here are some more details.
I live in northeast Ohio. 1,500 sq ft ranch on a slab.
The west wall (60 feet long) of my home has always been cold. But since adding vinyl siding to the home last year with Tyvek and continuous soffit venting, the drafts are getting worse and the wall is getting colder.

I jumped the gun and got a quote from an insulation company. I came to the conclusion I should figure out what's in my walls and exactly where the air is coming from before paying someone to install insulation that may or may not solve the problem. That's what prompted the IR scan.

The IR images showed fairly consistent leakage between wall and ceilings across the entire west wall. Some parts of the wall appeared to be fine, others deficient in insulation. One part of the wall on either side of full glass french doors had no insulation whatsoever.

Ceilings, windows, baseboards, other walls looked fine. I was also told compared to other slab homes, heat loss in the slab wasn't that bad. I also have a steel door that leads from an unheated garage into this living space that is transferring cold, too. It was suggested I replace that with an insulated door.

Beyond the door replacement, the auditor felt correcting the insulation on the back wall would improve the comfort in my home if payback weren't an issue and suggested adding closed cell foam.

Most foam companies here don't want to add foam into 2x4 walls with existing fiberglass insulation. They want to tear out existing insulation before adding their product. Airkrete, a cement-based foam is gaining in popularity in this area but the standard is closed cell foam. I've also been told that foam helps insulate the outside noise. Which would be a HUGE plus for me.

I think I'd like to try to seal the gap up in the attic and see if that makes a difference first. Thank you so much for your input. You're a great help to many on these forums.


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