Exterior
Chapel. coursed rock-faced Pembrokeshire grey limestone with red brick dressings and slate roof. Limestone quoins, raised plinth. Projecting gable front with coped shouldered gable and gabled kneelers. Single stair tower projects sideways to right, this with canted hipped roof. Italian Romanesque style with big centre triplet of 3 arched lights, the surrounds and two column piers all bi-colour, red brick and grey-brown sandstone. Centre light has stilted head. Sloping brick with black brick patterns below windows down to stone sills. Below, a carved double scroll, the upper one inscribed 'Westgate', the longer lower one 'Calvinistic Methodist Chapel 1828 1866'. Ground floor between two narrow single lights, with bicolour heads but sandstone sides and sills. The door is doubly recessed, outer arch bi-colour brick and limestone, arched on underside, pointed on upper side, on chamfered limestone jambs. Inner arch has chamfered jambs and red brick arch with stone keystone. Double doors with diagonal boarding, under sandstone flat lintel on two shaped sandstone corbels. Brick infill above with pattern in black brick. Matching doorway in rebated left side wall of front projection.
Stair tower to right has window similar to those on ground floor, at mid level, and another similar window set higher in side wall.
Chapel is set in a slope with basement schoolroom, exposed to rightside. Two storey, 4-window range with tall arched upper windows, sandstone frames, bi-colour arches, and cambered headed basement windows in similar frames, door in grey limestone frame between third and fourth windows. Plain rendered rear wall.
Upper side has similar 4 arched windows, but with small gabled single-storey projection between third and fourth, built across basement area. Arched door in limestone frame to front. All windows are metal, probably mid C20 replacements.
Iron railings around interrupted by paired grey stone gatepiers with painted square slightly brattished caps, possibly of terracotta. Fleur-de-lys finials to rails, on grey stone coping.