I purchased a large, heavy shelf and was planning to put it up on an interior, hollow wall. Realising that I really needed to make sure it wouldn’t come down because, if it did, it would land on my bed and cause serious damage to my partner and I if it happened at night. I also didn’t want to have to pay a tradesman to come and put up my shelf for me. That would be expensive- potentially costing more than the shelf! So I did a little research on how to put up something heavy on plasterboard.