Glenalla Chapel, including forecourt gates and railings

Glenalla Chapel is a building dating from the early 20th century, constructed of brown snecked rubble stone with extensive Bath stone ashlar dressings and rendered side elevations. The north front is two and a half storeys, with a slightly projected and raised central section that increases to an attic storey visible above the eaves. Stepped ashlar buttresses flank the central section, terminating just above eaves level, and two ashlar bands decorate the facade. One band runs at first floor sill level, extending across the outer bays, and the other at eaves level. Quoins and further stepped buttresses are present on the outer bays. The ground floor features three arched doorways constructed of ashlar with hoodmoulds; the central doorway is larger, incorporating part-fluted column shafts and double panelled doors, while the outer doorways have single panel doors. Each doorway is topped with a radiating bar fanlight. Narrow single-light windows with arched ashlar surrounds and hoodmoulds are located in the outer bays. All windows have marginal glazing bars. The first floor has three arched windows with ashlar column-shafted surrounds, featuring 'Florentine' pattern glazing bar tracery consisting of two arched lights and a roundel above, but without emphasised mullions. The window heads are linked by slightly lower stilted arches, with outer column shafts creating an undulating arcade of alternating narrow blank rubble panels and wide windows. Shorter windows are also present in the outer bays, and an impost band runs along the facade. Above the eaves, a large rectangular ashlar panel ('1909 Methodistiaid Calfinaidd Glenalla') is set within the gable shoulders, which also features an arched triplet of windows with column shafts, moulded linked heads, a broader central glazed light, and blank rubble stone side panels.

The side elevations show a plain design with arched upper windows, a single light on each side and a two-light window in the centre. Five matching windows are located below. Hoodmoulds link these windows, and a string course runs along the elevation.

A rock-faced rubble front wall supports iron railings and pyramid-capped stone piers leading to a central gateway, complete with matching iron gates.