You must prepare your lawn area before installing turf. Remove any weeds and debris, level the soil and drainage, and add topsoil if necessary. Make sure that the area is levelled and drains well before installing the turf rolls, which should be laid tightly and watered. https://www.tumblr.com/turfsupplies/809158808407621632/site-preparation-checklist-before-laying-turf-in?source=share