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Heat loss top and bottom of walls


strudel's Avatar
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Join Date: Oct 2005
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03-10-10, 05:43 AM   #1  
Heat loss top and bottom of walls

Thermal imaging of my home indicates significant heat loss where the ceiling meets the walls, around my baseboards and the 12 inches above every window where they meet the ceiling.
I live in Ohio and my home is 2x4 construction, 35 years old, all electric, on a slab with ductwork in the slab, fiberglass insulation in walls, full ventilated soffits, baffles in every stud bay, full ridge vent, and a combination of blown cellulose and fiberglass batts R-50 in the attic. I sealed as many gaps as I could find up in the attic where holes were drilled for electrical etc. Insulation extends over where the walls meet the ceiling up in the attic but the soffits remain clear. Also removed all baseboard trim and foamed the void where the wall meets the slab. I do not have crown molding. I don't have icicles and the roof remains evenly covered with snow. The heat loss has me stumped. One insulation contractor suggested that maybe the fiberglass batts were cut short top and bottom. Another told me the heat loss around the home perimeter is just typical of slab. Any DIY solutions to help minimize the heat loss? Any harm in drilling holes 6 inches or so down from the ceiling and adding spray foam?

 
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Bud9051's Avatar
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ME

03-10-10, 06:19 AM   #2  
Hi strudel,
Part of what you are seeing is the wood framing, thermal bridging. Over the windows there is usually a solid wood header to support the gap created by the window. Top and bottom of the walls have horizontal running 2x4's, one on bottom and two on top.

Deciding "what next" depends upon what is there. Your efforts sound positive, but there may be air sealing you missed, or other problems besides those walls. Did you have an energy audit or just a thermal scan. If you have more information, like additional results if it was an energy audit, or how bad your heating costs are we may be able to fine tune your improvements.

When you air sealed, did you do just the attic of the whole house? Here is a link that covers a wide selection of leaks.
http://www.efficiencyvermont.com/ste...ide_062507.pdf A little slow to open, but good.

If you haven't had a blower door test done, that combined with the infrared will really demonstrate where the leaks are.

If you want to do some calculations on heat loss yourself, there are several calculators on the internet. The benefit is they will/can break down the loss by area, thus you get a better picture of "where next".

Bud

 
strudel's Avatar
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03-10-10, 11:23 AM   #3  
Bud,
Thanks for posting that pdf. It's great. I had an audit, but not the blower door test. To make a long story short, I've lived in my electric home for 6 years. The electric bills aren't that bad. I've long suspected a lot of the heat is being absorbed into the slab through the ductwork before it even reaches the registers. I had the audit done hoping to find that answer and didn't. The guy didn't have a clue. Nor did he offer any suggestions to solving the heat loss shown in the IR pics. Thanks for the reply and great pdf!

 
Bud9051's Avatar
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03-10-10, 11:49 AM   #4  
There are a couple of issues related slabs and especially ducts under them. If there are any water/moisture issues, the heat loss can be substantial. So, drainage around your home is important. Along with that, perimeter insulation can greatly reduce the heat loss to mother nature when buried under the ground around as much of the house as possible. Basically, if water is not carrying your heat away either through drainage or leaks that evaporate inside your ducts, then where would it go. The old China joke . But as heat transfers into the soil below your slab, the farther it goes the more resistance it encounters and resistance to heat flow is the definition of R-value. So 6 feet of dry soil under your home actually gives you some good insulation. But as this plume of heat builds, it also spreads out where it can come to the surface and be blown away. 4' of rigid insulation around the perimeter forces that heat to travel farther and thus slows the heat loss.

The edge of the slab is also a concern and should be covered with something. IR photos of slab edges are scary.

As a note, if you are experiencing higher humidity levels, forced hot air is usually dry, then there is a possibility of moisture seeping into those ducts. They have a reputation and IMO should be on your replace or fix list at 35 years of age. I have to be careful recommending that old things need to be replaced, as the wife has had me on that list for many years .

You can take some temperature measurements on your heat ducts to maybe get an idea if there is a lot of loss. If you measure the temp of the air at the source and where it exits the ducts, they should be the same. Any loss would correspond to a temperature drop. If the plume of heat is dissipating between heat cycles, this loss will be more noticeable at the start of the cycle.

More questions, more answers.

Bud

 
Desert Eagle's Avatar
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03-10-10, 09:52 PM   #5  
Strudel, as Bud indicated you did not have a real audit. No BD.

"Thermal imaging of my home indicates significant heat loss where the ceiling meets the walls, around my baseboards and the 12 inches above every window where they meet the ceiling."

That is normal ,it is probably what the yahoo carrying the IR camera told you. ( just so you know, anybody can buy one.)
What amazes me is he didn't have a sales pitch to fix it. That is a lame con man.

Anyway, find a real auditor. Someone that has a duct blaster, pressure pan, blower door, and knowledge in your local building practices.

Search: "HPwES contractors" for your area.

 
strudel's Avatar
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03-11-10, 05:07 AM   #6  
Boredom set in last night and I decided to lift the edge of the carpet around the exterior wall of one room. There is a quarter inch gap that is between the slab and what appears to be some type of foam insulation that butts up to the cynder block foundation. When we put in new baseboards, I foamed the gaps behind them, but this gap is under the drywall and never saw it. The gap extends down three inches. I presume it's time for some low expanding foam or caulk? Just don't want the foam oozing out onto my carpet and baseboards. Thanks all for your input.

 
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