..ikea besta units hung on plasterboard wall. each unit is 60cm * 64 height * 20 cm. total 300 cm. total size of wall is 352 cm. we then have a piece of wood we want to make 3 shelves to make up the balance of 52 cm. so each shelf will be 52cm in width also, we need an ikea unit 60cm width * size hung on a tiled wall in bathroom. Plaster a small area about 30cm * 30 cm in sitting room - easily accessible