Gilfach y Berthog

Gilfach y Berthog is a large house comprising a main range with rear wing, built of rubble stone with a slate roof. The front gables are partly coped with moulded kneelers, and the rubble end chimney stacks have rebated angles.

The main southeast front is 2½ storeys, with the rear wing rising to 3 storeys. The front elevation is symmetrical, featuring central double half-glazed doors within a doorcase of wooden columns and deep entablature. To either side are 2 windows per storey: the lower storey windows are 2-pane sashes with marginal glazing, while the upper storey contains 17th-century high-transomed windows incorporating casements. A single 20th-century gabled roof dormer sits centrally above. The elevation is particularly striking for its decorative plaster panels, which are wholly uncharacteristic of southwest Wales. The decorative motifs—notably concave-sided diamonds—resemble the timber-framing tradition of Montgomeryshire and the border areas. An especially elaborate diamond panel sits above the doorway. The front also features implied quoins at either end and moulded eaves.

The right gable end has a gable stack. The 2-window rear wing is entered on the left side of the house. Its main central entrance comprises a massive 6-panel door within an open-fronted canopy supported on posts. The windows are not equally placed: the lower storey has a 4-pane sash window to the left and a small window to the right, while the middle storey contains 12-pane horned sashes and the upper storey 9-pane horned sashes. The rear gable end has a massive chimney breast with a rounded bread oven projecting to the northeast. A similar bread oven on the southwest side is contained within a thickened corner, which has narrow windows to mezzanine rooms—the lower is slit-like and the upper has a stone mullion. A modern brick lean-to stands on the right side of the rear wing.

The interior retains significant 17th-century and later features. The original entrance in the main front opened to a passage between the two principal rooms, though the left-hand wall has since been removed. The drawing room to the left has a fine Gothic chimney piece with inscribed ornament and foliage capitals to stout columns, with a foliated bracket cornice. A blocked chimney stands to the rear wall. The doorway from the drawing room into the dining room features an exceptionally deeply moulded cornice over a simple bolection moulded architrave with panelled double doors. The doorway into the hall has similar treatment. The dining room has a deeply panelled ceiling with moulded cornices in each compartment, supported on stone corbels to the rear wall. A fine overmantel with Ionic pilasters and a blind cartouche is dated 1692 to either side.

The main modern entrance opens to a former parlour in the cross range. Its ceiling features broadly chamfered cross beams, simply stopped at one end, with closely spaced joists—probably dating to the early 17th century. A deep fireplace with domed bread ovens to either side has a timber lintel. A partition wall between the parlour and the steps to the stairwell is formed of stop-chamfered studs over a high rubble base.

The overall character of the main part of the house relates to the 1692 remodelling. The fine openwell staircase rises to the attic storey with barley-twist balusters, square newels, and a shaped handrail. The stair ceiling has lightly ribbed panels and window seats, with the stair rising to broad landings. The first-floor landing retains a blocked cross-frame timber window. Some panelled doors survive, including one 2-panel door with early fielding. One first-floor rear bedroom has an exceptional full-height chimney piece with irregular Ionic columns, a moulded surround to the overmantel, and panelled ornament to the fireplace lintel. Another first-floor front bedroom has one part-wainscotted wall. The stairs lead into the mezzanine levels on the south side of the cross range, which have low ceilings; one room has a slit window. A-frame pegged roof trusses with overlapping purlins are exposed, and the cross range roof structure is similar, suggesting the whole house was reroofed at the time of the 1692 remodelling. A small flat-roofed cellar is present.