architrave - beam that spans from column to column.
asphalt shingle - mixture of bitumen and crushed rock, used as cladding for exterior walls or roofs.
astragal - small semi-circular moulding or beading; one application is to the outside of a fence, at the point where the pickets are attached to the inside rail.
balcony - railed platform projecting from wall, generally in front of a door or window.
baluster - one of a row of vertical members supporting a handrail.
balustrade - row comprising balusters topped with a handrail, sometimes having a bottom rail; used on verandahs, porches and stairways.
bargeboard (vergeboard) - plain or decorative board fixed beneath the eaves of a gable to cover horizontal roof timbers or rafters.
barn sash - double-hung sash windows, each with four or six panes of glass, panes separated by muntins.
basement - storey beneath main floor, either above or below grade.
batten - narrow strip of wood covering joints as in board-and-batten siding.
battered - inward tilt of wall or pier from base upwards.
bay - window section which projects from building face, usually built from ground level, but can be jettied or cantilevered; may vary in shape - bow (curved), angled, boxed, etc.; may be one or more storeys.
beaded or beading - small semicircular moulding, frequently with beads and reels; astragal is one type of beading.
bellcast - flared bottom edge of a roof or wall surface.
belt course - wide string course.
bevel - sloping surface, usually on an edge.
board-and-batten - siding which consists of wide vertical boards nailed edge to edge, with the joints covered by narrow strips of wood (battens).
bollard - short metal or concrete post used to tie up a boat or to restrict access, ie: vehicular.
boxed bay - squared off bay window section; frequently cantilevered.
bracket - projecting support from a wall, column or post; may be plain, moulded, turned or carved.
bullnose - rounded edge on siding or front edge of stair treads.