# Foundation heat loss and insulation.



## Brian26 (Nov 16, 2019)

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 (Nov 16, 2019)

Brian26 said:


> 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.


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## Brian26 (Nov 16, 2019)

Sawset said:


> 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 (Nov 16, 2019)

My phone has a flir camera built in.  We did 2" foam inside.  I prefer outside insulation that involves lots of excavation


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## Rob711 (Nov 16, 2019)

Who makes a camera with flir thermo built in?


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## begreen (Nov 16, 2019)

Brian26 said:


> 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.
> 
> ...


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.


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## begreen (Nov 16, 2019)

Rob711 said:


> Who makes a camera with flir thermo built in?


CAT S60


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## Highbeam (Nov 17, 2019)

So where is the “after” flir shot? I assume this is not a vented crawl space? More like a basement?


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## Wooden Head (Nov 17, 2019)

Brian26 said:


> 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.
> View attachment 251500


I took a look on the FLIR site. The price was $199 and you will need the correct operating system Version


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## EatenByLimestone (Nov 17, 2019)

How small of a hole shows up?  Can you see a gap in a sill plate or sheathing?


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## Seasoned Oak (Nov 17, 2019)

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.


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## spirilis (Nov 17, 2019)

Seasoned Oak said:


> 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...


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## peakbagger (Nov 17, 2019)

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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## ABMax24 (Nov 23, 2019)

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.


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## maple1 (Nov 25, 2019)

Would really like to see some Flir shots of the OP from after insulation.


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## Brian26 (Nov 25, 2019)

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 (Nov 26, 2019)

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 (Nov 26, 2019)

maple1 said:


> 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 (Nov 26, 2019)

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.


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## peakbagger (Nov 26, 2019)

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.


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## Brian26 (Nov 26, 2019)

maple1 said:


> 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 (Nov 26, 2019)

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 (Nov 26, 2019)

peakbagger said:


> 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.


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## Brian26 (Nov 27, 2019)

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 (Nov 29, 2019)

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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## twd000 (Dec 6, 2019)

Brian26 said:


> 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.
> View attachment 252269


that's kind of a silly set of assumptions for a comparison.  Most people with un-insulated basement walls don't use it as conditioned space.  Does anyone actual run gas furnace ducts into a basement with bare concrete walls?

My basement is un-conditioned but already about 3/4 finished with some fiberglass batts and drywall.  The 1/4 un-conditioned section gets pretty cold, but that's where I lager my homebrew!


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## Brian26 (Dec 6, 2019)

twd000 said:


> that's kind of a silly set of assumptions for a comparison.  Most people with un-insulated basement walls don't use it as conditioned space.  Does anyone actual run gas furnace ducts into a basement with bare concrete walls?
> 
> My basement is un-conditioned but already about 3/4 finished with some fiberglass batts and drywall.  The 1/4 un-conditioned section gets pretty cold, but that's where I lager my homebrew!



Its the 2nd law of thermodynamics that heat flows from hot to cold. The basement is usually one of the coldest spots in the house. Massive amounts of heat flow through your floor into your basement and right out your house. Your thinking since heat rises its all going out your attic/roof but your actually losing more heat through walls/flooors and the basement then the attic.


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## twd000 (Dec 6, 2019)

Brian26 said:


> Its the 2nd law of thermodynamics that heat flows from hot to cold. The basement is usually one of the coldest spots in the house. Massive amounts of heat flow through your floor into your basement and right out your house. Your thinking since heat rises its all going out your attic/roof but your actually losing more heat through walls/flooors and the basement then the attic.




I'm not sure I'm following you.  Indeed, heat rises by convection from basement to attic.  Heat also conducts sideways from the basement to the ground outside.  Whether the amount of heat loss is greater from the basement or the attic, depends on the specific basement and attic in question, how well sealed and insulated they already are.  I don't doubt that your house will lose less heat than it did before you foamed the walls.  But the portion of your basement wall below the frost line has a boundary temperature of 55F, which doesn't suck away nearly as much heat as the exterior boundary temperature of 20F, or 0F on the remaining walls & attic, etc.


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## Brian26 (Dec 7, 2019)

Finally got the spray foam done on the foundation sill plate. I got the 2 tank dow frothpak from lowes. Its my first time using this stuff and its really amazing product. So easy to spray and completely airseals and is r6 inch.

Its going to drop into the teens tonight so it will be interesting to see how it performs with the flir.


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## laynes69 (Dec 26, 2019)

Brian26 said:


> Finally got the spray foam done on the foundation sill plate. I got the 2 tank dow frothpak from lowes. Its my first time using this stuff and its really amazing product. So easy to spray and completely airseals and is r6 inch.
> 
> Its going to drop into the teens tonight so it will be interesting to see how it performs with the flir.
> 
> View attachment 253053


Any updates on the improvements?


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## Brian26 (Dec 26, 2019)

laynes69 said:


> Any updates on the improvements?



Its been a massive amount of work but I have all the insulation in and I am installing the drywall now. Was definitely worth it. The basement temps are significantly higher and are mostly around 60 degrees now. The most noticeable difference is how much warmer the floor above is now.

Here are some FLIR shots with just the insulation up. You can still see the heat loss soaking down through the floors and upper basement walls. Good visual of how heat will also travel down through colder floors. I might experiment with a section of basement  ceiling with some mineral wool and see what it does.

Has anyone insulated a basement ceiling?


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## peakbagger (Dec 26, 2019)

Those froth packs are great except I feel guilty with all the stuff I end up throwing away at the end. I wish they could come up with a system that generates less trash.


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## laynes69 (Dec 26, 2019)

Brian26 said:


> Its been a massive amount of work but I have all the insulation in and I am installing the drywall now. Was definitely worth it. The basement temps are significantly higher and are mostly around 60 degrees now. The most noticeable difference is how much warmer the floor above is now.
> 
> Here are some FLIR shots with just the insulation up. You can still see the heat loss soaking down through the floors and upper basement walls. Good visual of how heat will also travel down through colder floors. I might experiment with a section of basement  ceiling with some mineral wool and see what it does.
> 
> ...


Very nice! Every little gap and crack all adds up as well as missing insulation. I'm in the process of adding a second bathroom upstairs and I just finished drywall from a gut job directly down below. Everything that I've sealed and insulated has made a huge improvement on the house. While I need to foam the sills in our basement, at this point I just have alot more to do to finish the new bathroom. Eventually I'll get there!


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## begreen (Dec 26, 2019)

Brian26 said:


> The basement temps are significantly higher and are mostly around 60 degrees now. The most noticeable difference is how much warmer the floor above is now.


That's exactly what I noticed when I turned our crawlspace into an insulated, conditioned space.


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## Seasoned Oak (Dec 27, 2019)

Brian26 said:


> Has anyone insulated a basement ceiling?


The only reason to heat a basement ceiling is if the basement is kept colder than the 1st floor. My friend was building a ranch house and was going to insulated the basement ceiling .Since he was also going to put a woodstove in the basement i explained insulating his basement ceiling would be counter productive by stopping the heat from warming his upstairs floors.


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## Brian26 (Jan 18, 2020)

Its been pretty mild here but we finally got some real cold. Its 11 degrees out and I just went out with the FLIR. I think I am going to go R20 and add another 2 inches of foamboard. My unfinished basement with  no heat source has stayed around 50-55 all night which has been a massive improvement.  It would drop to the 40s with similar temps before the insulation.

This FLIR shot still shows foundation temps in the mid 30's.  Though that could be ground temps soaking in?

I have r20+ in the walls and the FLIR shows it as outside air temps  when measured off the siding.

I am going to add another 2 inches of foamboard and will report back.


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## Seasoned Oak (Jan 18, 2020)

I was putting up board foam today and the wall temp was the same as the room temp .Uninsulated walls were 10 to 20 degrees colder then room temp.


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## Brian26 (Jan 18, 2020)

I went outside this morning and shot the foundation again. I read a research paper that suggests the foundation actually wicks heat from the ground and that is what I was seeing. Its been pretty mild here and it makes sense as soil temperatures were still quite high.

Foundation was 17 this morning.  All I can say is insulate your foundation if its not as the results have been beyond impressive.


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## Seasoned Oak (Jan 19, 2020)

Looks like your house is very well insulated with heat only escaping from windows and doors which can be expected.


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## begreen (Jan 19, 2020)

How are the heat pumps doing at 6º @Brian26 ?


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