Roof Valley Support

[padstar]

I am not sure if this is best for the building or the carpentry forum but i am after clarification on supporting a roof structure for an extension.

I will have 2 slopping roofs forming a valley as shown below. Does it matter that there is no load bearing structure internally near or under the valley rafter?

Is it ok for the valley rafter to sit purely from a wall plate fixed to the existing structure down to the new external wall? The spans aren't large but i was just wondering about the forces coming in from the right hand side roof being purely supported by the valley rafter. Is this normal or do i need any additional strengthening?

 

[noseall]

Yes it is acceptable for one roof to lay on another via a 'lay-board'. We tend to use a new scaffold board as a lay-board.