I am working with builder to replace the ceiling in the loft of my 200 year old house.
The old ceiling has been taken down and we are going to put joists between rafters for the new ceiling, attaching to the rafter just above the existing purlins.
In the loft room two purlins run down each side of the room each purlins runs from the gable wall to a central structure that supports the other end. But there also two additional braces that traverse the room and run under the two northern purlins and the builder says it is okay to remove since when we add the two new celing joists these will tie pairs of rafters together and provide further support, but Im not so sure. Each brace is notched out to run under the purlin and bolted to the purlin from the bottom on one side and then attched to the rafter on the other side. So one brace is attached to the left purlin and one to the right purlin.
I know purlins mainly support the rafters (and it turn is supported by load bearing walls), but since each has a v notch under each purlin it seems it is intended to somehow support the purlin rather than tie the rafter to the purlin. Since the main central brace that supports the central structure also has these vnotches and this is clearly intended to support the purlin.
Note I use the word brace and vnotch for the want of a better word.