Tan-y-dderwen

Tan-y-dderwen consists of a pair of deliberately asymmetrical cottages located in Abergwyngregyn. Built in the mild Gothic style favored by the estate, they feature snecked rubblestone and a slate roof with bargeboards on slightly overhanging verges. The long main range runs roughly parallel to the road and has a projecting gable offset to the right. Each floor of this gable has a 2-light, 8-paned window with slate cills, stone lintels, and voussoirs supporting segmental relieving arches.

On the right side, there is a lean-to infill porch that has a 20th-century glazed outer door, which serves as the entrance to No. 2. The entrance to No. 1 is located on the far left, accessed through a 20th-century half-glazed door beneath a slate-roofed lean-to. This lean-to is bracketed around the doorway and extends to the junction with the gable, which includes a multi-paned canted bay window on the right. Above the bay window, there is a raking dormer featuring a 2-light, 12-paned casement that breaks the eaves.

The cottages have brick ridge stacks with rebated diagonal shafts, positioned to the left and right of the gable, with the right stack rendered and a similar stack located behind the ridge on the left. There are also single-storey 20th-century additions to each cottage. The interior was not inspected during the survey.