How to tell if plaster walls are insulated

Our home was built in Michigan in 1929. It's a cinder block basement w/ cement floor, and at the top of the basement wall we can see where wood framing rests on the top of the cinderblock, so I'm assuming it's a wood frame house on top of the cinderblock foundation. I see wood panels under the aluminum siding outside (which is where chipmunks are going, but that's a different story).
Our house is IMPOSSIBLE to heat, so I'm thinking we have no insulation. The walls inside are plaster. When I look at the little cubby space behind the wall in the 2nd floor (it's a sloped roof, and the walls of the room are straight, so there's that little unfinished triangular space where you can store stuff behind the wall along the length of the house), I DO see some kind of old insulation in the rafters; it's black paper with all this crumbly red nasty stuff behind it. It looks like the equivalent of the fiberglass stuff you see today, just all crumbly and cruddy. I can't look down the walls, though, because the slope goes out past the walls, so the floor of the cubby space comes to a point where the sloping roof is going down.
Is the only way to tell what's behind our plaster cutting holes and tearing out whatever we come to until we see either insulation or the outside surface of the wall? Might there be a better, less damaging way (like taking one panel of aluminum siding off, removing that big wood siding piece, etc., except that actually seems harder)?
I'd like to know if we can use that blown insulation stuff, but I think I need to know what's behind there to know if it's possible.
Thanks for any tips, ideas, etc.
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The age of the home, by itself, is sufficient reason to assume that the walls were not insulated when it was built. [snip]

You're not going to be able to look down the walls anyway. They have 2x4s at the top as well as the bottom.

Remove a baseboard. Cut a hole in the plaster about 1.5 inches above the floor and look inside the wall. Replace the baseboard, thus hiding the hole.

Yes, you can -- but I think that you're probably better off hiring that job done instead of trying the DIY route.
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On Jun 28, 9:21 pm, snipped-for-privacy@milmac.com (Doug Miller) wrote:

I bet its not insulated so get it checked.
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Often you can see between the electrical boxes and the wall space. Unless the house was upgraded, it is 99% certain NOT to have insulation if build in 1929. Yes, it is possible to put blown in insulation in the wall, but it may take some special equipment and/or techniques. I'd call a pro and see what they have to offer.. They see this all the time and can best help you.
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Thanks everyone for the excellent help. I feel much more comfortable asking for opinions here than the local contractors. I think I live in a college town where none of these contractors really need to do good work or become true experts in their field, because 90% of the homes here are student rentals that continue to get in worse and worse shape, and by the time anything needs to be done it's practically a demolition job anyway.
Whatever the reason, I've had nothing but bad experiences with consults, from them saying things that even I know is wrong (like an inspector saying our sump pump empties directly outside into the yard, without even looking up the pipe to see that it terminated), or completely disagreeing with each other and saying that I'd destroy the house if I did what the OTHER guy said. It's been pretty bad. I much more rely on people who actually have experience and the desire to do good work. I recently learned to solder water pipes and installed our new water heater (no big feat to you guys, I'm sure, but a major accomplishment for me, especially since I saved $400 in exorbitant installation costs by buying a pipe cutter, some pipe, a torch, and flux), so I feel like maybe I'll be able to do more and more given the time and good advice.
Thanks again.

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If your house has not been rewired since 1929, you most likely have no insulation and have knob and tube wiring which can create a problem with blown in insulation. If the wiring has been updated to current grounded cables, you may have some insulation added at that time, but probably not.
Just a word of caution that knob and tube wiring can overheat if buried in insulation. Many insurance companies are refusing to insure buildings with knob and tube, so it may pay to replace it just before adding insulation.

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You really need an energy audit and a blower door test.
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Perhaps your local utility company will do a free energy audit for you.
CompleteNewb wrote:

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What you need is a Thermographic camera. Go to Wikipedia and look it up. Beg, borrow or buy, they cost around $2,000. With this you take photos of the walls and roof, the various shades show how much heat is leaking from your home and where
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