Vestry attached to left of Llwyncelyn Independent Chapel

The vestry is attached to the left of Llwyncelyn Independent Chapel. It is built from coursed squared stone and features a slate roof with bracketed eaves. The lateral facade includes two large arched windows with an arched plaque between them and tall arched outer doors, all made with stone voussoirs. The windows have 24 panes and radiating-bar heads, while the doors are two-panel with both five-pane overlights and radiating-bar fanlights above. The rear is slate-hung over a rubble stone high plinth, with two square-headed long 32-pane sashes and a 16-pane sash on the upper level of each end wall. The slate-hung gable end is above the attached roughcast vestry, which has a slate roof, a roughcast end stack, and a large 16-pane pivot window on the upper floor front above a small ground floor window. There is a door in the end wall, and a parallel-roofed, windowless range behind.

The interior is handsome, featuring a three-sided gallery supported by plain iron columns with capitals. The gallery front has simple cornices above and below, with vertical panels and curved angles. The box pews are raked, painted-grained, and panelled in both the main part and the gallery, along with a later pine great seat. The original pulpit is timber panelled and painted grained, with curved angles and raised high on a panelled base, accessed by a single flight of steps from the right. A thin plaster arch is behind the pulpit, and there are lobbies in the angles with multi-pane windows filled with coloured glass. The ceiling is plaster with three sides and features a simple central rose.