How much will I need?

For hempcrete (wet-cast or blocks), or for lime plaster or render materials, we usually recommend allowing 5% for wastage/cutting on top of the volume you think you need. However this is obviously at the customer’s discretion. If you are calculating the area of plaster or render needed, don’t bother subtracting the area of any window or door opening under 2 square metres as the area of the reveals will usually make up the difference. For openings over 2 square metres in area, just subtract the balance over 2 m2 in each case.