The joists are attached to load bearing walls by two common methods.
Timber flat roof fascia detail.
Flat roof joists spanning the shorter length of the roof form the load bearing members of the structure.
The roofs have a timber frame as the supporting structure.
Having a manual for warm flat roof construction with details and a summary of rules to follow helps.
Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading.
Gravel stops and fascias are used where flat roofs end to provide a weathertight transition between roof and wall.
For additional stability you can also use steel joists that are built into one or both of the walls.
A timber decking is then constructed and its weight supported by the joists.
The construction of the flat roof is similar to that of the timber upper floor.
I explain problems with insulating a roof using the warm and cold roof construction methods.
Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls.
The details shown concentrate on combined gravel stops and fascias.
Whatever new flat roof covering you choose epdm rubber kemper.