Our contractor just finished renovating renovating our bathrooms and I am trying to estimate how much tile he ended up using (in sq ft). The most accurate way would be to take all the tile receipts, figure out how many sqft we bought, then subtract whatever was returned to the sore and left over. Problem is, I lost some of the receipts. So what I did was imply measure all the areas that were covered by the tile. Of course, this does not take into account any waste (broken tile, cut-off pieces etc). Is there a rule of thumb on how to roughly estimate the amount of tile "overhead" as the %age of the square footage installed? Thank you.