Simple pitched roof on timber building

[Kombi Camper]

I am planning an outhouse/gardenroom/shed. It will be a basic rectangle 6.5m wide by 4m deep. e.g front and back 6.5m and the sides 4m. I want to use corrugated cladding (aesthetic reasons) on the walls and roof so I have decided to build a pitched roof and not the flat rubber one I thought I was going to build. I have cut birdsmouths before and understand the rafter calculations to get all my cuts right but I cannot find any infomation on how to tie the front and back wall together. I know my roof will be relatively lightweight but I can't help thinking that it will push the front and back walls out if they are not braced together. I want to insulate between the rafetres so that when you walk into the room and look up you see the full height, like a vaulted ceiling. I cannpt find any info on how to construct that. Am I being super dense? The stud walls will be made from 6x2 and I am hoping 6x2 will also be good for the rafters. DO I need cross members> If so where can I find details on construction options? Many thanks 

[George]

You cannot built a vaulted roof in the same way as a traditional or truss roof. You should talk to a structural engineer about what you want to do.

 

Essentially you need a ridge beam (not a ridge board) to carry the rafters to prevent lateral thrust on the walls / reduce it to a manageable level.

[Kombi Camper]

28 minutes ago, George said:

You cannot built a vaulted roof in the same way as a traditional or truss roof. You should talk to a structural engineer about what you want to do.

 

Essentially you need a ridge beam (not a ridge board) to carry the rafters to prevent lateral thrust on the walls / reduce it to a manageable level.

 

thanks George. I don't want to talk to a SE about a small timber building with a lightweight roof. As I understand it you only need a ridge BEAM if your roof is 14 degrees or less. Mine is 22.5 degrees. I read that here https://todayshomeowner.com/roofing/guides/ridge-board-vs-ridge-beam/#:~:text=The ridge beam transfers the,%2F12 and 12%2F12.

Edited May 13, 2024 by Kombi Camper

[George]

That is talking about shallow pitched roofs. The other reason for a ridge beam is if you have a vaulted roof. In which case the roof pitch is irrelevant (unless it's flat!). 

Edited May 13, 2024 by George

[joe90]

1 hour ago, Kombi Camper said:

As I understand it you only need a ridge BEAM if your roof is 14 degrees or less. Mine is 22.5 degrees.

That is not true, you need either ceiling joists or a ridge beam to stop wall spread.

Edited May 13, 2024 by joe90

[Iceverge]

Contact your local truss manufacturer about scissors trusses. 

 

They'll look vaulted from inside and their magic engineering software will do all the hard calcs for you. 

 

 

[Galileo]

On 13/05/2024 at 15:19, Kombi Camper said:

 

thanks George. I don't want to talk to a SE about a small timber building with a lightweight roof. As I understand it you only need a ridge BEAM if your roof is 14 degrees or less. Mine is 22.5 degrees. I read that here https://todayshomeowner.com/roofing/guides/ridge-board-vs-ridge-beam/#:~:text=The ridge beam transfers the,%2F12 and 12%2F12.

 

You could potentially use a few collar ties in the upper third of the rafters rather than full trusses or rafter ties and still insulate between the rafters and get a vaulted look.

 

That article you quote does clearly show that a tie is required though if using a ridge board: