1 Rowallan Street, Helensburgh

1 Rowallan Street, Helensburgh, is a two-storey Scottish Arts and Crafts villa dating from 1895, designed by A. N. Paterson. The house is constructed with harled walls and red sandstone dressings, arranged in an asymmetrical L-plan. The south elevation features windows with raised sandstone margins, cornicing at ground level. Elsewhere, windows have sandstone sills and lintels, and are mullioned. A crowstepped gable is a prominent feature.

The east elevation, facing Rowallan Street, features a lop-sided gabled bay with a central architraved doorpiece. The door surround has a basket-arched opening with a stop-chamfered roll-moulded detail. The door itself has lead-pane glazing to the fanlight and upper panels, with a more modern door set within a deep vestibule. Above the tympanum is a canted window topped by an open-apex pediment. A wallhead stack stands to the left, and a small window is located at first floor level to the far left. A ground floor window is present to the right, and a later two-storey block extends to the outer right, with harled walls at ground level and grey slate hanging at first floor.

The north return is gabled and slate-hung at first floor, with a tripartite window. The south garden elevation features a single-storey and attic crowstepped gabled bay on the right, with a corniced canted window at ground level and a tripartite attic window above. Two ground floor windows are positioned to the left, above which is a tripartite flat-roofed dormer.

The west side elevation reveals lop-sided gabled bays to the outer right and left. Four ground floor windows are spaced along the elevation, with a door positioned off-centre to the left. An ashlar pedimented window breaks the eaves to the right, alongside two further windows. A first-floor window is set within the gabled bay to the far left. A lower block to the outer left contains a lean-to porch, and a gabled dormerheaded window breaks the eaves above.

The north rear elevation includes two small ground floor windows in the re-entrant angle, alongside a tripartite timber stair window with a cross bar above each light. The window has lead-pane glazing incorporating stained glass. A two-storey service wing projects to the right, connected to the main house by an engaged circular tower with a door facing northeast and a small window above. A small window is set to the outer right, and a gabled return on the north shows evidence of a removed wallhead stack.

The majority of windows are sash and case, with plate glass in the lower sashes and six-pane upper sashes. The roof is covered in grey/green slate, with ashlar coped skews, beak skewputts, and ashlar coped stacks.

The interior retains original chimney pieces and a timber balustered staircase.

Red sandstone gate piers support wrought-iron gates.