Pitch roof, loft trusses clarification. Can I remove or cut a trusses to introduce a beam

[Jonny Vee]

The ceiling joists effectively tie together the feet of the rafters on opposite sides of the roof to make a triangular structure.

You can replace the ceiling joists with deeper 8x2s which - as well as tying the rafter feet - would also form your new floor. BUT, if the new joists are split by the 152 x 89, they will not be as effective at tying the rafter feet together and the roof might spread long-term.View attachment 191142

Thanks for the sketch. Your option would make sense but does not work on my case as I would have to expose a beam below the ceiling and wife is completely against it.

I understand the joist are part of the structure and let leave them alone. Don't want mess around with that. What about my proposal below?

Double the joist number to reinforce/help the old twisted ones and will put 50x150mm blinders instead of the old 50x100 with 400mm center to match beam height to have a flat flooring. Would this make a stronger flooring? The new blinder will have a span of 3.5mm and set to the existing ceiling joist which is set on top of a wall bearing wall. Any Thought?

 

[Leofric]

Your drawing doesn't show the existing ceiling joists tied to the rafter feet (as Tony 1851 explained ) but I would get your structural engineer who designed the steelwork to check what you are doing on the overall roof construction anyway.

 

[Jonny Vee]

Your drawing doesn't show the existing ceiling joists tied to the rafter feet (as Tony 1851 explained ) but I would get your structural engineer who designed the steelwork to check what you are doing on the overall roof construction anyway.

The green hatch is the existing joist as per annotation on the drawing attached. Orange are the new one sitting on top

 

[Leofric]

The green hatch is the existing joist as per annotation on the drawing attached. Orange are the new one sitting on top

Yes ,but the existing (green ) joists aren't shown extending far enough to connect to the rafters. I presume they do in reality.

 

[Jonny Vee]

Yes ,but the existing (green ) joists aren't shown extending far enough to connect to the rafters. I presume they do in reality.

You are right, This was a quick schematic drawing. As you can see most of the joist are nailed to the wall plate and not directly to rafters.