R-tistic license

[blackfacespikeyhair]

Can anybody tell me if it is acceptable to use multiple layers of foil insulation (eg Thermawrap) and simply multiply up the R value of one layer by the number of layers to get the overall R value? If possible, this would be a great space saver!

Thanks in advance for any advice!

[Softus]

In my unqualified opinion, the answer is that it isn't that simple.

The U value of a given sheet will be a function of whatever is next to it. If you place several identical layers together then the effectiveness of insulation of each one will be affected by its neighbour, so you can't just multiple the value for one sheet by the number of sheets.