Differences in reproductive interests between the sexes can affect web construction behaviour, which can vary across ontogeny. This study tested whether exploration and web building behaviour varies with age and sex in Physocyclus globosus (Pholcidae), a spider that weaves an irregular, domed sheet web with a tangle above. Spiders were placed in cages with four interconnected chambers. Most fifth instar juveniles and adult females (but only half adult males) wove a sheet in only one chamber. Adult females built the denser sheets. Although adults attached more threads to the walls than juveniles, the latter attached more new threads there over time. Juveniles laid 91% of their threads in the sheet chamber, compared to adult females (55%) and adult males (41%). All spiders (especially adult males) attached many exploration threads throughout 18 days, suggesting repeated abandonments of the web. The reduced rate of exploration by juveniles suggests that they establish webs more quickly to increase the possibility of prey capture, intense foraging, and rapid growth. Exploration or web construction did not differ between the sexes in juveniles. Adult males explored more often, perhaps looking for mates, while adult females modified their web structure after establishing, perhaps to improve prey capture rates.