Making up height difference under rafters with double timber acceptable?

[Digmixfill]

Ladies and gentlemen of the jury,

 

New internal leaf stepping back from original walls is causing a height difference between the west and east wing of our L shaped building.  Is it acceptable to stack timbers in wall plates?

 

In the mocked up example I have a stunt valley rafter sat on a 75mm wall plate in the outer corner of our L shape. The wall plate is around 1.6m in length and passes through to the south wing, and has another piece of timber above it to take up the extra space beneath my stunt common rafter. Laser level is set to the masonry top on the west wing.

 

 

[saveasteading]

If I am understanding this properly then, yes you could stack timber plates. Just note that you get double the shrinkage.

Why not build up the masonry instead?

[Digmixfill]

If I build up the masonry where the common rafter is it would make the wall plate timber under the valley rafter very short. Probably 300mm long.

 

 

[Digmixfill]

It's not clear from the images I posted earlier, but the block wall in the picture is short. It provides a cavity to the outside wall up to perpendicular wall of the single story room on the other side.

 

I would get two or three common rafters on the double stacked wall plate and the valley rafter on singe depth end of it in the room to the left. New common rafters would continue in the existing wall plate position to the right.

 

[saveasteading]

22 hours ago, Digmixfill said:

Probably 300mm long

Can't see that being a problem.

[Digmixfill]

38 minutes ago, saveasteading said:

Can't see that being a problem.

 

Really? It would make my life much easier if I could use a small plate under the valley rafter alone and then step up to different level on the other side of the wall.  The thing that steered me away from that is "Wall plates should be a minimum of 3m or extend over at least three joists".

 

The valley rafter wall plate would fail all of those requirements. The small wall part might also fail those. I don't think I can get three common rafters on it at 600 spacing unless the first rafter is tight up against the wall.