The second purlin was intended to act as a trimmer for the stack, carrying the ends of the rafters where they were interrupted by the chimney stack construction and as such could not meet the wall plate in the usual manner.
32.
The roof, which has served as a model for restorations at Bunratty Castle and Rothe House, is arch-braced with four oak principals; on each collar-beam stands a king-post supporting a purlin and cross-pieces below the ridge.
33.
Other load bearing timbers use the term plate but are not in the wall such as " crown plate ", a purlin-like beam carried by crown posts in roof framing, and a " purlin plate " which supports common rafters.
34.
Other load bearing timbers use the term plate but are not in the wall such as " crown plate ", a purlin-like beam carried by crown posts in roof framing, and a " purlin plate " which supports common rafters.
35.
Advance Steel has a library of more than 300 preset parametric steel connections to connect Advance elements grouped in the following categories : beam end to end joints, base plate joints, general bracing joints, cantilever beam to column joints, plate joints, clip angle joints, pylon joints, tube brace joints, purlin joints, stiffener joints, turnbuckle bracings, etc.
36.
In his book " A Visual Dictionary of Architecture ", Francis D . K . Ching defines a knee wall as " a short wall supporting rafters at some intermediate position along their length . " The knee wall takes the place of a purlin, providing support to rafters which therefore need not be large enough to span from the ridge to the eaves.
