Rafters in Ridge Steel beam help

[OrangeJuice09]

Hi, I'm having a vaulted ceiling and a Ridge Steel has been fitted. Internally, I want a triangular ceiling.

I was wondering how the rafters should be fitted on the steel. I've attached an image with two options.
1. where the rafter fits into web of steel with noggins
2. add a bolted timber in web and attach rafters to timber (I assume with some form of hanger)
Can either option work ?
(A third option would be to fit rafters on top of the ridge)

I could not find the associated building regs on this, hence my question.

 

[noseall]

There are lots of ways to position the ridge beam deep ding on design. Most end up with a flat too due to the need for collars beneath the ridge beam.

Vaulta1

• noseall
• 6 Feb 2022

Vaulta2

• noseall
• 6 Feb 2022

P1020304

• noseall
• 24 Jan 2021

Beamsite2

• noseall
• 16 Feb 2020

Vaulty2

• noseall
• 7 Feb 2020

Vaulty1

• noseall
• 7 Feb 2020

 

[noseall]

There are lots of ways to position the ridge beam deep ding on design. Most end up with a flat too due to the need for collars beneath the ridge beam.

Vaulta1

• noseall
• 6 Feb 2022

Vaulta2

• noseall
• 6 Feb 2022

P1020304

• noseall
• 24 Jan 2021

Beamsite2

• noseall
• 16 Feb 2020

Vaulty2

• noseall
• 7 Feb 2020

Vaulty1

• noseall
• 7 Feb 2020

 

[OrangeJuice09]

Thanks for a rapid response!
I noticed there's several ways in how these are connected. My preferred option is rafter in the web (as per drawing). The carpenter had a look at it and said its wrong, hence was confused. I dont want the inspector to fail it

 

[jks7492]

Either of the two is fine.
Depending on the type of joist hanger you use if you go with option 2, you may need to notch the underside of the timber for it to sit in the hanger like you've shown on the first sketch

 

[noseall]

Thanks for a rapid response!
I noticed there's several ways in how these are connected. My preferred option is rafter in the web (as per drawing). The carpenter had a look at it and said its wrong, hence was confused. I dont want the inspector to fail it

Rafter just slotted into the web is no good. Rafter connected to a timber infill (via jiffys) that has been fixed into the web of the steel is fine.

 

[martygturner]

You cannot just slot the rafter in, that cut top and bottom will reduce the structural strength , all the load will bounce on that notch cut corner and the bottom. Before you do it make sure you know where and how the finish will sit to give you the shape you want. You may have to skin up the bottom of the rafters with batten to get the angle into the void between the steel and the rafter.

 

[noseall]

I want a triangular ceiling.

How are you going to deal with the inevitable collars or mitigate the lack of?

 

[martygturner]

We have got stainless tie bars running across, which turned out to be a good idea as we forgot about lighting said space.....

 

[Notch7]

How are you going to deal with the inevitable collars or mitigate the lack of?

Are collars needed for structural reasons on a vaulted ceiling?

I can see they structurally link the common rafters - which must help reduce flex or twist, maybe caused by wind load.

I can’t see from your pics if they are conventional pitched cold roof - but if so then the collar would help ventilation to continue.

My guess is if the OP wants a triangular ceiling, that would entail going back to the SE.

A triangular ceiling would make avoiding a cold bridge at the bottom of the steel an issue.

 

[cdbe]

I used heavy duty angled brackets to stop my rafters spreading:

 

[Mr Chibs]

I went through BCO when I built my vaulted roof, which has a wooden wall plate/ledger on top of the beam, and I used joist hangers.

I choose to box the beam in, and had no collars, nothing was mentioned by BCO that I had to have these, span was only around 4.6M front to back.

Thinking about what you are trying to achieve, could you not add battens/furring strips to the underside of the rafters to clear the beam?

 

[OrangeJuice09]

Are collars needed for structural reasons on a vaulted ceiling?

I can see they structurally link the common rafters - which must help reduce flex or twist, maybe caused by wind load.

I can’t see from your pics if they are conventional pitched cold roof - but if so then the collar would help ventilation to continue.

My guess is if the OP wants a triangular ceiling, that would entail going back to the SE.

A triangular ceiling would make avoiding a cold bridge at the bottom of the steel an issue.

The Structural Engineer designed the above steel. Collars should not be needed because the steel can support the weight of the load and is fixed on both ends.
I haven't drawn the diagram accurately, in reality, I'm putting in 7x2 rafters the rafter length either side is 2m. The bottom of the 7x2 rafter is lower than the bottom of the steel, meaning I can insulate to stop cold bridge forming and still form a triangular roof.
Insulation board added to bottom of rafters, Insulation added between rafters, Battens will be added and tiled. Is this a cold roof?

 

[^woody^]

The carpenter had a look at it and said its wrong

Because it is, despite it being possible.

How are you going to batten and tile over the top flange?

Rafters should load the top of the beam not the bottom flange.

 

[Dodgyrog]

If it helps I've just rec'd detail from my structural engineer. We're only vaulting one half of an existing roof / ceiling hence only one side of rafters shown and being fixed to existing rafters - but the general concept is the same.