Foundation heat loss and insulation.

Brian26

Feeling the Heat
Sep 20, 2013
440
Branford, CT
Been insulating and air sealing using my smarthphone FLIR to easily find all areas of heat loss. This flir shot of my foundation wall outside shows how much heat loss uninsulated exposed concrete foundations have. It was quite staggering and all that orange/white is some serious heat flowing right outside.

I just started putting up some r10 foamboard tapconed into the foundation. I am going to cover it with 1/2 sheetrock for fire code as well.

Has anyone else insulated their foundation walls? I have read that homes with uninsulated foundations have total home heat loss around 15-30%. Seems insulating them could bring big energy savings but this is one area that nobody thinks to insulate. I believe it has been code to insulate for awhile but tons of home have none.
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Sawset

Minister of Fire
Feb 14, 2015
637
Palmyra, WI
using my smarthphone FLIR to easily find all areas of heat loss.
Could you explain this a bit more. App and phone. Or an additional device?
We've put up r10 (2") Styrofoam, glued and taped, and will be putting up 2x4 studs plus drywall to finish. Would be curious to see the heat loss and compare. The furnace room has 1" outside as does everything, remainder r10 inside as well.
 

Brian26

Feeling the Heat
Sep 20, 2013
440
Branford, CT
Could you explain this a bit more. App and phone. Or an additional device?
We've put up r10 (2") Styrofoam, glued and taped, and will be putting up 2x4 studs plus drywall to finish. Would be curious to see the heat loss and compare. The furnace room has 1" outside as does everything, remainder r10 inside as well.
FLIR has a 150$ thermal image camera that plugs into a smarthphone. Its an absolutely amazing tool for finding air leaks and heat loss areas.
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bholler

Chimney sweep
Staff member
Jan 14, 2014
19,483
central pa
My phone has a flir camera built in. We did 2" foam inside. I prefer outside insulation that involves lots of excavation
 

Rob711

Burning Hunk
Oct 19, 2017
244
Long Island, ny
Who makes a camera with flir thermo built in?
 

begreen

Mooderator
Staff member
Nov 18, 2005
79,699
South Puget Sound, WA
Been insulating and air sealing using my smarthphone FLIR to easily find all areas of heat loss. This flir shot of my foundation wall outside shows how much heat loss uninsulated exposed concrete foundations have. It was quite staggering and all that orange/white is some serious heat flowing right outside.

I just started putting up some r10 foamboard tapconed into the foundation. I am going to cover it with 1/2 sheetrock for fire code as well.

Has anyone else insulated their foundation walls? I have read that homes with uninsulated foundations have total home heat loss around 15-30%. Seems insulating them could bring big energy savings but this is one area that nobody thinks to insulate. I believe it has been code to insulate for awhile but tons of home have none.
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Nice, that should help a lot. When we lifted the house and put it on a new foundation I insulated the entire crawlspace and turned it into a conditioned space. The difference has been huge. Floors are comfortable, ductwork stays warmer, and the crawlspace rarely drops below 55-60º.
 

Highbeam

Minister of Fire
Dec 28, 2006
16,497
Mt. Rainier Foothills, WA
So where is the “after” flir shot? I assume this is not a vented crawl space? More like a basement?
 

EatenByLimestone

Minister of Fire
Jul 12, 2006
7,172
Schenectady, NY
How small of a hole shows up? Can you see a gap in a sill plate or sheathing?
 

Seasoned Oak

Minister of Fire
Oct 17, 2008
6,549
Eastern Central PA
Uninsulated underground walls do have a benefit in summer of keeping the basement cooler than the rest of the house. I guess it depends if you spend more on heat or cooling if it will pay.
 

spirilis

Minister of Fire
Sep 8, 2009
918
Frederick, MD
Uninsulated underground walls do have a benefit in summer of keeping the basement cooler than the rest of the house. I guess it depends if you spend more on heat or cooling if it will pay.
+ brings on mold/mildew air quality issues in humid summer climates. Also something to account for there. Less need for a dehumifier with warmer foundations in the summer...
 

peakbagger

Minister of Fire
Jul 11, 2008
4,796
Northern NH
Some observations over the year about insulated foundations

We used to have stove in our basement when I was growing up. My mom grew roses and had them planted outside along the foundation wall. Her roses always bloomed early in the spring due to the heat from the stove heating up the ground from the basement. I remember as a kid that there always would be trench in the snow pack around the house foundation. It made for a good start to a snow fort. I look at homes with insulated foundations these days and the trenches are gone.

30 years ago when I built my house I wanted to insulate my foundation. Many folks advised against it as they thought that heat had to leak into the surrounding soil or otherwise the water running though the ground would freeze and crack the foundation. There was also debate about where to put the insulation, inside the wall or outside the wall. The local utility had a small rebate program and they would only give a rebate for insulation outside the wall. I wanted to insulate my basement floor but I couldnt find any concrete guy that would do a floor over insulation as they insisted it would crack. It was boom time for construction without a lot of options for concrete in my area so I ended up not insulating the floor although I wish I did. I ended up with 1" of foam on the exterior walls up to ground level and then put 4' down from the sill on the interior on two sides of the house. I did 1" of foam on the exposed concrete on the outside on the other two walls above ground level and regretted it. Carpenter ants used it to tunnel through up to the house sills and until I cut it back I was fighting them every year in the house.
 
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We have a 2x6" wall built on the inside of our concrete foundation with R-22 fiberglass batt insulation with vapor barrier on the inner most side. This was code when our house was built in 2014, our code was updated in 2015 and now also requires 4" thick foam insulation under the concrete slab.
 

Brian26

Feeling the Heat
Sep 20, 2013
440
Branford, CT
Here are 2 flir shots when the outside temp was around 30. There is a heat signature even with foam board up. I still haven't sealed the top of the foundation and sill plate as seen in my 2nd picture in the first post. So I am still getting some heat loss from that. I have a spray foam tank for that just waiting for temp in the 60s to apply it.

R10 foam board the exterior temp was just slightly above ambiemy at 33 degrees.

Bare concrete was pretty much the basement temp around 50. That is some insane heat loss.

I also attached a flir of my mini split when it was subzero out. The foundation was glowing like crazy with heat loss which was really why I started looking into the foundation insulation. Exterior heat loss is crazy to look at when it's subzero out. I remember looking at the foundation and was like wow. In the mini split shot even the ground was showing heat feet away from the house!
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maple1

Minister of Fire
Sep 15, 2011
10,107
Nova Scotia
I have thought about this, since seeing it when I first got my Flir a couple years ago and went outside with it on a really frigid winter night. It is a pretty eye opening sight - but I don't think it is all from basement heat through concrete. I already had foam board inside, in places where I was seeing it. I think some of it, is from the concrete conducting heat vertically up from the warmer ground down below. When it is really cold out, the ground at the bottom of the wall is a lot warmer than at the surface. Could be 50° down below, and -20° or whatever the outside temp is at the time. Quite a dT.

Still think that is some of it, but those last pics seem to show better that yes indeedy there are gains to be made by insulating basement walls.
 
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Brian26

Feeling the Heat
Sep 20, 2013
440
Branford, CT
I have thought about this, since seeing it when I first got my Flir a couple years ago and went outside with it on a really frigid winter night. It is a pretty eye opening sight - but I don't think it is all from basement heat through concrete. I already had foam board inside, in places where I was seeing it. I think some of it, is from the concrete conducting heat vertically up from the warmer ground down below. When it is really cold out, the ground at the bottom of the wall is a lot warmer than at the surface. Could be 50° down below, and -20° or whatever the outside temp is at the time. Quite a dT.

Still think that is some of it, but those last pics seem to show better that yes indeedy there are gains to be made by insulating basement walls.
Huge gains. Close to a 95 percent reduction in heat loss with r11 according to a study done in VT.

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maple1

Minister of Fire
Sep 15, 2011
10,107
Nova Scotia
Oh I agree - it's just that in my case at least, the Flir pic was a bit misleading, because it was showing what looked like huge loss even with insulation on the inside.
 

peakbagger

Minister of Fire
Jul 11, 2008
4,796
Northern NH
After I put the 1" foam on my interior foundation walls I had an energy audit done and they recommended sealing the sill boxes and sills with foam. I thought the sills were tight and had fiberglass in the boxes but I removed the fiberglass and they sprayed the boxes, the sills and then down to the top of the foam. it made quite a big difference.

Folks forget that unless they have radiant floors, most floors above a basement are uninsulated and they are cold if the basement is cold. I think most folks get chill off the floor and crank up the thermostat. If the basement floor is warm I can drop my Thermostat a few degrees. Since I have the wood boiler in the basement and 500 gallons of storage that tend to keep the basement warm when I run the boiler but when I run the minisplit for heat its noticeable.
 

Brian26

Feeling the Heat
Sep 20, 2013
440
Branford, CT
Oh I agree - it's just that in my case at least, the Flir pic was a bit misleading, because it was showing what looked like huge loss even with insulation on the inside.
Totally agree. You would think that flir of the 33 degree foundation is much hotter from the orange heat signature if you didnt see the temp reading. You really have to go off the temperature on the crosshair of the flir. I also used a infared laser thermometer to double check.

As soon as it gets colder I am going take some more flir shots. Will be interesting to see what it looks like in subzero weather with the insulation installed.

I did dig up another flir when it was subzero out before insulating. I remember snow actually had melted a few feet off the foundation.
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Seasoned Oak

Minister of Fire
Oct 17, 2008
6,549
Eastern Central PA
Im afraid my basement would be too warm if i started insulating. Its already 80 + in winter with no insulation from the heat off the boiler and water pipes. When i run the wood stove its even worse (90s). (Woodstove is in the basement) I would also have to insulate all the pipes and valves to the boiler i suppose to bring down the basement temps. Part of the reason its so warm is, on the other side of the basement wall is another basement wall to an adjoining property.
 
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begreen

Mooderator
Staff member
Nov 18, 2005
79,699
South Puget Sound, WA
Folks forget that unless they have radiant floors, most floors above a basement are uninsulated and they are cold if the basement is cold. I think most folks get chill off the floor and crank up the thermostat. If the basement floor is warm I can drop my Thermostat a few degrees. Since I have the wood boiler in the basement and 500 gallons of storage that tend to keep the basement warm when I run the boiler but when I run the minisplit for heat its noticeable.
We noticed an increase in comfort right away after insulating the crawlspace walls. The floors are definitely more comfortable to walk on in winter.
 

Brian26

Feeling the Heat
Sep 20, 2013
440
Branford, CT
I googled some payback numbers and found this chat from a federal study. Didn't realize the payback numbers are this high especially considering the fuel was natural gas in the study. I would imagine much larger savings with propane or oil. I bought 10 sheets at $34 each so I will recoup my cost in 1 winter.
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Brian26

Feeling the Heat
Sep 20, 2013
440
Branford, CT
Got all the foam boards up but still need to spray foam the top and foundation sill. Still losing a large amount of heat. The spray foam has in huge letters on the tank that temps must be above 60. So need some prolonged warm weather.

These flir shots show it well.
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