How do I know if my basement is insulated?

Last year I helped a friend with her basement rim joist problems. The basement was under insulated but cold and floor were always cold and robbing a lot of heat upstairs. When I pulled out the little bit of glass someone stuffed up in the rim joist area cold air just poured in. I foamed the big gap and let it to harden up and when I went back it was amazing how it had changed. We put the glass back in and added more but I don’t think it did much. Stopping the draft was 99% of it.

If you have siding that snaps on its not that hard to take a couple rows down. It may be possible to do some good without taking the ceiling down. Most people dread opening the ceiling but that also isn’t that much to fix if you are careful how you open it up.

Your question is hard to answer because we don’t know the whole picture. You can keep anything warm as toast if you pump enough heat to it. It’s hard to say.

It is like trying to keep warm by swallowing your sweater. Doesn't work you should wear you sweater instead.

A basement should be insulated from the outside in. So you want to start there around your foundations with a strong vapor barrier such as blue skin, keeping the dampness out a couple inches of polystyrene at least.

Jungle said:

It is like trying to keep warm by swallowing your sweater. Doesn't work you should wear you sweater instead.

A basement should be insulated from the outside in. So you want to start there around your foundations with a strong vapor barrier such as blue skin, keeping the dampness out a couple inches of polystyrene at least.

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Over that sweater put on a rubber rain coat and get to work and see how that works. New rain gear can breath just like house wrap.

Jungle said:

A basement should be insulated from the outside in.

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In principle and as to only heat loss or gain it should make no difference which side the insulation is on but there may be practical considerations that dictate one side or the other [beside the expense of excavation].

Can you post a link to a pdf file that supports your position/assertion/opinion/fact?
TIA.

2" Of Styrofoam around the outside should make the concrete walls much warmer.

/watch?v=kwn0Vjw_ji0

Can you insulate the outside walls above grade? The rim joists are the problem.

I suppose you could, but it depends on what you have out there. you will want a flashing that goes behind the siding and house wrap above it and cover it so it looks nice.
Something like this just higher.

I have a brick exterior, can this still be done?

Brick absorbs water and releases it toward the inside, there is a space beteen the brick and wall to allow the water to run down and out wipe hole beween brick in the bottom row. The flashing in my photo would go behind the brick and house wrap. So in a word "no" I would sooner loose a little heat, than mess with the outside. You could be causing much bigger problems.

Jungle said:

2" Of Styrofoam around the outside should make the concrete walls much warmer.

/watch?v=kwn0Vjw_ji0

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Good link about heat transfer and vapor transfer. I'll have take notes on this video, it goes fast.

Here are my unedited notes from the cold climate video which may serve as a checklist.
It seems that for existing construction, you'd need some way of measuring vapor and water transfer, relate that to basement comfort and decide what your comfort is worth in dollars.

Basement insulation

[ame]http://www.youtube.com/watch?v=kwn0Vjw_ji0[/ame]

Cold climate research

-below grade heat loss is outward, vapor pressure is inward.

-above grade, in winter vap out, in summer it's in.
-understand moisture flow, liquid and vapor
-capillary wicking water upward. Need a capillary break between footing and foundation.
-vapor comes in two ways, by air and diffusion (pressure), Soil is 100% RH.
-preferred is to put water membrane (spray on or roll on) and insulation outside so water & vapor does not saturate the walls. Then the wall stays warm and if any moisture is in the wall it can rapidly be dried out by the basement air.
-basement wall moisture content strongly predicts joist moisture content by vapor transfer. Joist insulation makes it worse. So extend the outside insulation over the rim joist.

-You can insulate from the inside but it has to be perfect because the wall moisture control has not been taken care of. The cold basement wall will get condensation. And if your basement floods the interior fiber insulation has to be removed.
-You could use styrofoam on the wall interior but basement wall surface has to be dry. The bottom foam edge needs to be sealed.
-The slab has to stop water from underneath so use aggregate to allow drainage and prevent wicking.
-Seal the sump lid to prevent humid air coming into the basement.
-Use a thermal barrier under the slab because warmer is drier and the slab becomes part of the conditioned space.
-Don't carpet the slab.

-The lump sum cost of exterior insulation may pay for itself over time. This insulation needs to be protected from physical damage. Interior insulation systems are risky but may be cheaper in the short run.
-Use paperless drywall for finishing, no insulation, use flat latex paint.

-The rim joist should also be part of the conditioned space.
-You could use spray foam inside but it may not bond properly. The joist may absorb moisture.

InTooDeep said:

I bought a house with a finished basement. Its always cold there. And gets colder the further away from the furnace. Before I start any attempt to fix it I want to know if the problem is the low or lack of insulation. Is there a way to know this without ripping down the drywall?

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You only mention the furnace, is there any other form of heating down there?
A room can feel cold, because you are too warm or because there is no heating or the heat is escaping.
How much heat are you putting into the rooms (same space) above? Are they warm? Are you putting the same amount of heat into the basement? Do you want to keep it at the same temperature? What temperature are the rooms above? What temperature is the basement?

For example, the palm of your hand is probably 30C, the walls of your living room are probably 20C, when you touch them they feel cold, the basement walls also feel cold to touch, they may be the same temperature, they may be colder.

Heat is lost from your 37C core temperature by conduction, convection and radiation.

A room with colder walls will feel colder even if the air temp is the same (radiation) but IIRC with a 50F or less air temp people feel cold no matter how hot the walls are.

Touching wood (a thermal insulator of sorts) at 72F will feel warmer than touching aluminum (a thermal conductor) at the same temp (conduction).

Moving dry air will feel cooler than moving still air (convection).

And women's comfort zone for temp and humidity is different than men's.

Fascinating subject, it should be taught at school.
So many people have trouble understanding.
One thing that troubles me about the insulation industry and builders is, that a Polar bear has a two inch thick fur coat, yet with a body temperature of 37C it can play quite happily in temperatures of minus 30C, we on the other hand need insulation five or more times thicker.
Industry is missing something.......builders seem to just ignore radiation.

Perry525 said:

Fascinating subject, it should be taught at school.
So many people have trouble understanding.
One thing that troubles me about the insulation industry and builders is, that a Polar bear has a two inch thick fur coat, yet with a body temperature of 37C it can play quite happily in temperatures of minus 30C, we on the other hand need insulation five or more times thicker.
Industry is missing something.......builders seem to just ignore radiation.

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They used to have a resi HVAC system with an outside temp sensor that boosted the inside temp a bit depending on how cold the outside got. Maybe that somehow didn't work out but the principle is sound.

Apparently humans gave up fur, claws, fangs, speed, strength and night vision for increased brain capacity.
Fair trade?

One thing that troubles me about the insulation industry and builders is, that a Polar bear has a two inch thick fur coat, yet with a body temperature of 37C it can play quite happily in temperatures of minus 30C, we on the other hand need insulation five or more times thicker.

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That's why I insulated my basement with bear fat. Acquiring the fat was nothing compared to the installation

(no bears were actually hurt in the making of this post)

Thanks for all the replies. Follow up question. I ended up opening some more walls only to find that there was pink insulation but no vapor barrier (no plastic film or tar paper). Is a vapor barrier needed in a basement against the exterior walls?

The vapour barrier should be next to the drywall, the idea is to keep warm moist air from the house from getting into the framing in the wall, if you are not finding any problem with rotting wood I would not worry to much about it.

I found a bit of black wood along the floor. Everywhere else seems fine. I do plan to have the basement as a living space. So I'm worried that I won't be able to keep it warm in the winter. I live in Canada.

With a screwdriver poke at the black wood to see how solid it is, compare it to clean wood higher in the wall. If it is soft and mushy you have a problem.
Any wood that is in contact with concrete will draw moisture from the concrete.
In the wood structure upstairs there are holes and gaps in trhe sheeting that allow moisture to get out of the wall if it gets in there. the vapour barier stop house air from entering the wall. In the basement there is less chance of moisture getting out because it is a more sealed unit. so with the black wood you know you have some moisture at the floor prehaps not having a barrier is a better bet. Experts have fought about this for years.
Your biggest heat loss will be the windows and doors and the biggest problem is to get enough heat into the basement (HVAC design)
I live near the coast in BC and live in a basement suite. We have 4 inches of fg in the walls, to stop noise transfer and add fire stopping we closed off the heat and added electric baseboad heat
We also added a 4" air intake to provide air for the kitchen and bathroom fan. The only thing I would change now is something on the floor, the concrete is cold.

What you want to be sure about is the water isn't leaking thru the concrete wall, the age and condition of the weeping drain on the outside, to keep it dry

The black wood is kind of a go/no-go, binary, test. A moisture meter with needle probes may allow you to map out the intensity of moisture problems in your wood at several locations.
You might as well know the full extent of any problems.

I'm surprised at how warm the ground temps are for Canada, Fig. 2 of this link
http://archive.nrc-cnrc.gc.ca/eng/ibp/irc/cbd/building-digest-180.html