Insulation Under Carpet

I've got an old log shed that has a concrete floor. I plan to put a woodstove in, but I need ideas for something insulative to put between that cold hard concrete and some rugs or a carpet. It has to be cheap or free and readily available...this is just a temporary shelter while I get the place going.
I've considered newspapers but the fire hazard just scares me too much, and besides they're not real soft. I've thought about trying to collect unwanted foam rubber mousepads, since they seem to be plentiful and are becoming obsolete. Easy to clean. I'd only need 150 or so, duct taped together. I've considered styrofoam packing peanuts, but they'd be awfully lumpy and noisy.
Got any IDs?

[croston]

I have lived in a wooden converted barn for years and I have used newspaper under the carpets.Its soft enough if you put them down thick enough. The fire risk has never bothered me much as everything else about the building would burn anyway. I put my wood burner on stone slabs so that is safer. I do not let anyone smoke in my home and I am very careful about candles and cooking etc.

[dale]

sometimes you can go to a carpet store and get those small carpet squares that they use to show people what the carpet looks like.
maybe they would like to get rid of a bunch of them.

Sometimes the padding for carpet isnt all that high.

is there a factory around that has foamrubber scraps? there used to be a sporting goods factory that had alot of scraps after making football shoulder pads. mabe a mattress factory. who knows?????

[lacyj]

Look in the dumpster, behind the carpet store. There is usually a bunch in it. Cut out the stained parts, if necessary...
lacyj

[Kirk]

I have lived on cement floors withjust plain carpet and pad for a long time without any ill effects. The cement takes a little longer to heat up but stays more even. Since its temporary I'd do the dumpster thing too.
You might find that if you are going it solo the small cabin may meet your needs and no need to build a castle.
Kirk

[Browsercat]

It might be a good idea to think vapor barrier if you do anything; concrete is porous to some extent, and a good coat of paint (with some non-skid sand stuff tossed in) might help the overall warmth of the place by keeping it dryer.

[gobug]

Put a layer of foil on the top under your floor covering!! It could even be potato chip bags. You wont believe how well it works. It reflects the heat of the living area back towards the living space and the heat/cold of the slab back to the slab. They make special products for this purpose. A roll designed to insulate the slab is 4' x 63' and costs $135 including shipping. I've heard others say any aluminum foil will work, just tape the edges. gobug

[agmantoo]

If the building is sitting on the concrete slab dig out around the outside perimeter and insulate it with closed cell packing foam. This will make the interior much warmer as the concrete will not conduct the cold of the outside earth.

[Shrek]

make papercrete out of the newspaper by mixing the cellulose with lportland cement, water and boric acid to render it fireproof. Trowel the slurry on the floor and let it dry.