"Tomorrow: air sealing an attic……."

Are there any special tricks or products that you use when the surface temperatures that you are air sealing are below freezing? I noticed that the specs for spray foams and caulking usually have a lower limit of 40 degrees or warmer. Sure you can warm spray foam up to 90 or 100 degrees for application but as soon as it touches the cold surface, would that cause a problem?

I'm not sure. I just keep foam, guns and caulk inside when not in use. I hope the top side of my sheet rock is above freezing :/. Usually the problem is that things are too warm up there. That's why air sealing is needed. I just saw a house with no insulation in the attic at all see a blower door reduction of 4,600 CFM 50 to 1,100 CFM 50 with common air sealing techniques. I have seen large expanses of two part foam fail. That is corrected by spraying water on the surface first.

http://www.tiptemp.com/assets/17/tipWD-35639-30.jpg

When I was adding layers of insulation to my attic, I used one of those cheap IR heat scanners.
It enabled me to detect areas with heat leaks and take corrective action. Very inexpensive and effective tool.
It allows you to remotely view areas that aren't easy to reach. Or areas that are unsafe to walk on.

When it's real cold in the attic, and the house heat is turned up to 70F, leaks are easy to find, even 15-20 feet away.
But when you get closer (5 to 10 ft), you greatly narrow down the location of the leak.
Here's an example of the range resolution of one model.
http://www.fluke.com/NR/rdonlyres/3C...atio_250px.jpg
At 1" spread per foot, at 20 feet, the detect zone would be 20"?
This one doesn't look that great, but by sweeping slowly across the area,
while watching the peak, you can really focus in on the leak.

Yeah, once you get all of the obvious targets (chases, top plates, chimneys, lights, etc) I usually take a peak around with the IR camera.

Latest Installment:

Air Sealing The Attic


http://i182.photobucket.com/albums/x...ps88a2bceb.jpg



http://i182.photobucket.com/albums/x...ps4422e750.jpg

I'm about 1/2 of the way through the attic. The difficult half. I've been working for about 6 hours so far and gone through as many cans of foam. I probably have 5 left of just air sealing. I'm also removing the balsam wool bags as I go. Then I'm going to make a 2' dam out of plywood around the hatch. I'm not air sealing the top plates at the perimeter. It's just too much of a PITA so I'm going to get the 2 part spray foam guys where I work to squirt those tricky spots.

It really is a shame I didn't take blower door measurements before I started all of this work. I still haven't run a blower door here. Maybe I'll look into getting one here this weekend to aid me in my attic air sealing.

EDIT:

Oh yeah. The heat pumps failed in January. Not in a mechanical sense. In a financial sense. $380 electric bill. I have never seen anything like that. Those damn things are off until it gets hot out. I guess they don't like the way I ask them to bring the house up to temp twice a day.

Thanks for these pictures. Never really were sure what people were talking about when they discussed foaming the top plates to air seal. I never ran into the 2x4s between the drywall sheets when I was in the attic before looking for stuff to foam. It's probably because there is about a 13 foot span without a wall going down the middle in the section I was looking. Good to know.

"Oh yeah. The heat pumps failed in January. Not in a mechanical sense. In a financial sense. $380 electric bill. I have never seen anything like that. Those damn things are off until it gets hot out. I guess they don't like the way I ask them to bring the house up to temp twice a day." Are your thermostat(s) seeing more than a degree or two of temperature differential and triggering resistance heat? $380 sounds like it.

ASHPs can't do everything. The irony is that when it gets colder out and you need more heat, they become less able to deliver the heat you need. But up to that point, they're amazingly cost effective.

If you understand the ASHP weakness, and prepare for the times when the temperature really drops, you'll do OK.

I'm still using ASHP for my heating until I get my project done. When the winter temp takes a nose dive, I 'circle the wagons'. I reduce the area of the house that needs to be heated by the heat pump. I also fill in with some gas heat from the kitchen stove for now... but I recently bought a small direct vent NG gas heater for that purpose. Now that my kitchen is much tighter, heating even a little bit with the gas stove is not a good choice.

I found that out with my CO2 monitoring project.

BTW, you really into video editing?

Best,

-AC

"I'm still using ASHP for my heating until I get my project done. When the winter temp takes a nose dive, I 'circle the wagons'. I reduce the area of the house that needs to be heated by the heat pump. I also fill in with some gas heat from the kitchen stove for now... but I recently bought a small direct vent NG gas heater for that purpose. Now that my kitchen is much tighter, heating even a little bit with the gas stove is not a good choice.

I found that out with my CO2 monitoring project."

Be sure you are also monitoring CO as well as that will be more important than CO2 monitoring.

The top plate sealing is really pretty important when looking at he big picture. The drywall is sealed to the adjoining piece but not to the structure of the wall so air is free to move up and down between the structure of the wall and the drywall. As you can see in my first pictures, I have sealed the rock to the plates and then along the strapping over the plates extending beyond a few inches because you can't get the seam under the strapping. In the second picture I'm sealing the top plate of the load bearing wall through the middle of my house. There is strapping right up next to it on either side acting as a nailer for the rock so I sealed the plate to the strapping and then the strapping to the sheetrock. Then the joists lap there so I sealed the seam between them in a continuous fashion with the rest of the foam.

I don't have electric heat so that isn't it. The original heat is a line gas fired Buderus boiler. I think the heat pumps just don't like raising the temperature so so drastically. So I'll continue to use the gas. At least until I have this place properly buttoned up. We'll see what happens next winter.

@AC Hacker,

I have a hobby of video encoding, as in format changing movies to make them smaller to take up less space on my file server, but I don't know much about video editing per se. Why do you ask?

Oh, I thought I remembered seeing a post from you in which I thought you mentioned that video editing was your hobby. I've been editing on a PC for about 17 years now, so it was of interest to me.

BTW, if encoding is your thing, I recently discovered the joys of using a very high-performance video card's GPU to do rendering. I was formerly dumping rendering jobs onto my quad core. The acceleration due to the GPU is simply amazing.

Best,

-AC