Heat Help Needed!!

[snailybailey]

I have, amongst other snails, 2 Tigers, who like the heat to be up quite high in their tank!
Over the winter they were fine with the heating being on in the house, but now its spring time we have turned the central heating off.
This has made the temp in the tank drop down to about 20 degrees, which the Tigers arent too impressed with!
I have bought a heat mat and stuck it to the side of the tank, but this has only brought the temp up to around 22-23. The Tigers seem to like it and are very active at around 28. I am aware that heat is escaping from the other side of the heat mat, and I need to "force" this heat into the tank instead, and have read that I need polystyrene to do this. However, at the moment I dont have any polystyrene! I will try and get hold of some in the next couple of days!
But what can I use in the meantime to keep the temp of the tank up? Would using tin foil/kitchen foil on the other side of the heat mat help to reflect heat back into the tank or is that a silly idea?!
Has anyone else got any other suggestions?
Thanks!

[aerliss]

I know that some people use tin foil. Pressing a folded towel over it the same as you would with poly should help too.

[Dusk]

If you have any bubble wrap, jiffy bags, bits of corrugated cardboard etc around, they'll all do a decent job of insulating if they're layered

[coyote]

Maybe if you stapled some tin foil onto some corrugated cardboard? I did that in a cold flat I used to live in a few years ago, and it helped keep the heat from escaping behind the steam heat radiators and be lost to the outside walls, and reflected more heat into the room.