Ridge beam height

[Matheo]

Good afternoon,

I am doing box dormer loft conversion on 1930's terraced house. I was wondering what is the maximum height I can place the RSJ at? I am making a cold roof so there won't be any insulation on the dormer joists and therefore I would like to get as much height as possible by placing the RSJ as high as I can. Would be my sketch correct in assuming that the brickwork on the top of the party wall should be removed? What is going to be taking the horizontal load imposed on the ridge beam?
Thank you very much for your help.

Theo

 

[tony1851]

The brickwork at the top of the party wall should only be removed on your half of the wall thickness.
There is no horizontal force on the steel beam.

 

[Matheo]

Thanks for the response Tony!

Would there not be horizontal force on the beam from wind? Is my understanding of how this works incorrect? Or is the wind force taken by front timber frame wall?

 

[tony1851]

Thanks for the response Tony!

Would there not be horizontal force on the beam from wind? Is my understanding of how this works incorrect? Or is the wind force taken by front timber frame wall?

The dormer front will transfer wind load to the floor and roof.
In turn, the roof and the floor of the dormer will be fixed to existing side walls and new dormer cheeks running parallel to the wind load.
As both the roof and the floor are boarded, they will act as rigid horizontal plates which in turn will transfer the wind load to the side walls.

This load-transfer mechanism is the reason most buildings are able to withstand horizontal wind loading.

 

[Matheo]

All clear now. Thank you for the answer.