Subsequent recording, excavation, and tree-ring dating have allowed a detailed history of the house to be reconstructed.
Ty Mawr is a rare surviving example of an important late medieval house typical of the Welsh Marches. It stands on a platform, created by cutting into the hill slope and redepositing the spoil on the downhill site. However, this was not the first building on the site: excavation has revealed drainage gullies which outline an earlier building about half the size of the present structure. Built of timber felled in 1460, Ty Mawr measures 17.5m long by 8m wide. It was of five bays, with an unheated chamber at the upper end, a two-bay hall with an open end hearth at its centre, a cross-passage by which the site was entered, and a lower bay where animals were stalled. The timber-framed building was ailed, with the exception of the base cruck truss which spans the centre of the hall. The fined quality of the timberwork and the cusped decoration suggests that Ty Mawr was an important house although, as yet, it has proved impossible to identify who built it.
The most important feature at Ty Mawr is the spere truss which forms the entrance into the hall. The posts are carefully chamfered and stopped and the side panels have large quatrefoils as decoration. There may have been a moveable screen in the centre, matched by a canopy over the far, or dais end of the hall, where the head of the family would have sat.