Both roofs with grass turf had slightly better water retention than sedum moss turf, but against that they were more vulnerable for dry season and were affected by dryness part of the season, especially in early summer.
Bæði grasþökin gáfu til kynna aðeins hærri vatnsheldni en úthaginn á móti báru þau vott um þurrk, litu illa út sér í lagi fyrri hluta sumars.