When frames are fixed on the door ways, a joint is formed in between the timber and masonry. This joint should be covered since timber and masonry do not bond. In buildings, different materials fixed together have joints that require to be covered. In expansion and contracting of different materials a gap will appear. Materials like glass and timber, glass and concrete, aluminum and masonry, glass and steel do not bond and thus a finish is applied on the joints.
When fixing door frames in a building, the passage should allow for a finish to cover the material joints. The design should be at least four feet. This will allow a nibs of four inches to be built on both sides of the door way. The frame is fixed in the remaining distance between the nibs. The door frame may be fixed flush on one side of the nibs. The other side may be recessed at least two inches from the nib ends. Alternately it is fixed midway on the nibs, so its recessed on both sides.
The finish to timber and masonry door frames uses architraves and quadrants. The architrave is used on the side where the door frame is fixed flush with the nibs. The quadrant is used where the frame is recessed into the nibs. The quadrant is a quarter round piece of timber. It is about three quarters of an inch thick. It is fixed at the ninety degree corner of the frame and the masonry. The architrave is flat with designs engraved on it. It is about one and a three quarters of an inch wide.
Once the door frame joint is ready for covering, the pieces of timber for finishing are measured. These are measured from the height above the floor skirting. Panel pins are used for nailing the architrave or quadrant onto the timber frame. The architrave is nailed at least one inch of the door frame. This is to allow adequate cover of the joint while exposing the frame. The quadrant is nailed right into the joint. These timber finishes are then painted or varnished for good aesthetics.