Architrave

Also called: door casing, window casing

An architrave is a moulded timber strip fixed around a door or window opening: it frames the opening, and part of its job is to cover the join between the opening's timber lining and the plastered wall.

How it is fixed to the wall

The architrave usually sits over a ground, a rough timber strip fixed to the wall before plastering, which gives the plasterer something to work up to and later gives the architrave something to fix to. There are two main ways to build the assembly. In one, an architrave moulding is fixed straight onto the edge of the lining that frames the opening, one construction option. In the other, a framed ground goes on first, and the architrave is then fixed onto that ground, when a framed ground is used. To mark out the moulding's width, a worker takes a piece of the architrave and, with its back edge set on the lines already drawn for the linings, sets off the width from there, a marking-out step. Part of the architrave's purpose, wherever it sits, is to cover the seam where the ground meets the plaster. Hiding that joint behind the architrave lets the maker skip cutting a splay, a shallow angled bevel worked along an edge to disguise a straight joint, or a groove, into the ground's edge, when the architrave covers the joint. Grounds can also double as part of the architrave itself, which permits a narrower architrave moulding to be used around the frame. Where the ground has been wrought, meaning planed and finished rather than left rough, the architrave or a fillet, a thin flat strip of moulding, covering the joint may overlap it by roughly half the ground's own width, for grounds that are wrought.

Grades of work: the base and the recess behind it

The base of an architrave, where it meets the floor or a plinth block, is not always a single thickness throughout. Some are stepped back in the centre instead, a profile known as a double-faced architrave. In ordinary work, the recess this creates is simply plastered at the back, common-grade work. In finer work, that recess is instead covered by a strip called the back lining, better-grade work. One end of the back lining fits into the sash frame's inner lining (the sash frame being the timber frame that holds a window's glazed sashes), and its other end is tongued or housed, meaning let into a groove cut to receive it, against the ground behind the architrave, again in better-grade work.

Getting the proportions and the fixing right

An architrave moulding should be sized large and bold against the flat wall around it, and it should stand in contrast to the finer mouldings used within the framing it encloses. As Ellis (1908) put it, architrave mouldings 'act as a frame to an opening, and to be effective, should be large and dominant, forming a strong margin to the flats of the surrounding walls, and contrasting with the smaller mouldings of the enclosed framings.' In the best class of polished work, the architrave is attached to its grounds with concealed fixings rather than visible nails or screws.

Plinth blocks, folding doors and curved trim

Where a plinth block, a block at the foot of the architrave, wider than the moulding itself, sits at floor level, the two are commonly joined with a simple butt joint, where plinth blocks are used. Older practice instead joined the plinth block to the architrave with a barefaced tenon, a tenon shouldered on one face only rather than both, plus screws, rather than a butt joint, traditional practice. A folding room door trimmed with an oversized architrave and skirting needs parliament hinges, hinges with a long knuckle that lets them project well clear of the door face, for folding doors with large architrave and skirting. Curved architrave, such as a window's casing trim (the American term for architrave-style trim around a window opening), can be shaped on a power feeder, a machine that feeds a workpiece steadily and evenly past a cutter.