Plas-yn-Llan is a large, sub-medieval, elaborately half-timbered house of two units and an end and lateral chimney. Another wing was added to the lateral chimney, but this has since been demolished. 19th-century additions were also made to the S side. Internally, the ground floor partitions have been lost, but some post-and-panelling survives to the first floor.

The house was restored in the mid-1980s, with the removal of some accretion. The box-framed rear projection was removed, together with the later half-timbered structure on the N wall. The removal of these and much plaster revealed much of the old wall face, which has now been restored, including a good deal of herringbone work.
Source: DE/DOM/SJ16SW, from reports by P. Smith
J. Archer, RCAHMW, 1.10.2004