Question: how to calculate how much underlay i need?
Answer: Fill in the boxes labelled 'Length' and 'Width' for each room or area required. Only use numbers. Enter all figures in Metres, like the example below – (There are 15 sq meters on a roll.) Calculate as many rooms as you like. When estimating for stairs, a rough guide is that 12 stairs requires 3m by 0.90m.