There is a sky light, where the old window under it must have broke and fell out. I want to cover the holes leading to it, less than 60 cm x 60 cm. Where can I get insulating clear sheets of plastic to cover them? That I can cut into the right size. It could be something else that I could cut into sheets. Below that I can put window plastic, so there are 2 layers for the heat.
To be clear, I want to cover the hole in the ceiling under the skylight (which is fine, but drafty). There is an area between the skylight and the rooms' ceilings (it's split between rooms), about 1 m tall.
I have tin snips, but if there is a better way to cut, let me know. I prefer smaller items or sheets since large ones are a pain to bring home, no car.
I'm asking for hard sheets, so they don't move (and make crinkly sounds) with the draft. But thin enough to cut.