Plas Tirion, Bro Garmon, is a 16th century house of rubble construction with pitched slate roofs, plain gables, and tall stone stacks. The structure is F-plan (though formerly E-plan) with a projecting 3-storey gabled crosswing at the right of a 2-storey main block. There is a 3-storey gabled porch with a segmental arch and original oak studded door. There are Irregular windows with 20th century wooden-framed glazing and c.1840 recessed slate lintels with labels to otherwise mostly original openings. The south-east side has a further, single-storey gabled porch with a round-headed entrance and similar door. The building retains several original features internally, including the first-floor and attic floor boards and an oak pegged doorcase.

(Source: Cadw listing description)
J Hill 21/06/2004

ADDITIONAL:
Plas Tirion is a multi-period complexe in the Conwy valley. Below the principal house there are several ranges of farmbuildings which include an earlier house.
1. The multigabled principal house commands a view over the Conwy valley. It is a winged gentry house with a T-plan hall range and cross-wing, and with storeyed porch and stair forming front and rear projections. The ground floor has a three-unit plan with parlour, hall, and kitchen cross-wing. The hall range has ovolo-moulded detail (beams, windows and door frames) and several plaster overmantels dated 1626 and 1628. The three-storey cross-wing has a roof of collar-beam trusses; the two-storey hall range has a tie-beam roof with raking struts.
Dendrodating of the dated 1626-28 N hall range failed to produce a convincing match. However, tree-ring dating gave a date of 1565 for the S kitchen cross-wing.

2. The farmbuildings below the house include a dilapidated range that incorporates a distinctive cruck-truss with blades of boxed heart (whole tree) rather than halved timbers. The cruck and purlins are heavily smoke blackened and belonged to a medieval domestic building. This is the passage end truss of a downslope sited range which has been reconstructed beyond the lofted end bay, although some framing of uncertain date is incorporated in the stone walls. Whole-tree crucks are found among early pre-1400 crucks in England (but which have proved elusive in Wales). In the event, sampling showed that the trees were felled at the end of the fifteenth century, perhaps when large trees were not available. The cruck is associated with a later cross-beam in the passage which may relate to an inserted floor.

Dendrochronology has therefore established an interesting and insome respects unexpectedly detailed chronology for the site:
1498 cruck-framed hall-house
1545/46 inserted beam (loft) at passage end of hall-house.
1565+ Snowdonian house (= S Wing)
1626-8 Enlargement, with the Snowdonian house becoming kitchen wing of the new range.
NPRN27773.

R F Suggett/RCAHMW/July 2012.