Dan-y-Graig-Isaf was 1km south of Heol Senni village, on the west side of the minor road to Ystradfellt and just north of a tributary stream running into the Afon Senni to the east. It was an ochre house with a white byre, of 1.5 storeys that was empty at the time of inspection. It was a true long-house derivative type house, with direct access between house and byre through a cross passage in the byre, though at time of inspection, with a blocked door to the house. It also had a step up to the dairy and pantry. The door to the kitchen was a pegged, plain chamfer with ogee and bar stop, with an ogee stop on the beam. It had a gable-end chimney and staircase. The wooden staircase over was over one of stone. The barn was sited downhill and parallel to the house. The house had an outside toilet, of the drain type, making use of the farm yard drain. From the 2000 OS Landline 1:2500 map it appears that the house is no longer in existence.
(Source: NMR Site files, H Brooksby, 8 January 1969; Brycheiniog 1968-9, Jones and Smith, 'The Houses of Breconshire', p. 77)
Ian Archer, RCAHMW, 4th March 2005