Beam 2.3m load-bearing wall

[robertua]

Hello,
We are expanding a single-story house of 104 sqm with 51 sqm.

- Truss rafters with a cold attic on the existing building, and it will be the same on the extension.
- The rafters have a dimension of 45x145 with concrete tiles, 27-degree pitch.
- Exterior wall has a stud dimension of 45x170
- Crawl space of concrete blocks in three layers with a dimension of 19x16x39 (wxdxl, cm). The extended crawl space will have the same height, but it is intended to use lecablock instead of concrete blocks.
- The concrete block rests on a concrete slab that is 60cm wide and 25cm high. The new crawl space will have the same size slab.
- The existing house is 12.34m long and 8.14m wide
- The extension is 7.65m long out from the existing house and 6.66m wide.
- Interior ceiling height is 2.4m

The problem: Between the existing load-bearing wall and the extension, we need to make an opening of 2.3m. I want the supporting beam to be as small as possible because it would look best aesthetically. My question is, what is the smallest beam we can have for the support?

Is there any kind soul who can help me without needing to contact a structural engineer for this? Building permit and excavation for the foundation are already done.

The highlighted area is the extension.

 

[Vante]

Glulam 66×315 works in snow zone 2.

 

[robertua]

Living in snow zone 1.5. But is there nothing that builds smaller?

 

[Vante]

90x225mm

 

[JA”Snabbe”]

Can't one use a steel beam?

 

[robertua]

Can't you use a steel beam?

Yes, you can, but the question is what size of steel beam I need that adds the least height?

 

[JA”Snabbe”]

Yes, it's possible, but the question is what size of steel beam I need and which builds the least height?

That's for the scholars to dispute. But it should result in a lower height with a steel beam compared to wood.

 

[justusandersson]

215x225 is the smallest glulam beam that is conceivable with the current opening length. 90x225 is not comparable to 66x315, it has much worse stiffness. In steel, HEA 140 should suffice. However, after installation, not much height has been gained.

 

[robertua]

215x225 is the smallest glulam beam that is conceivable with the current opening length. 90x225 is not comparable to 66x315, it has much worse stiffness. In steel, HEA 140 should suffice. After installation, however, you have not gained much in height.

Thank you Justsandersson! 215mm wide is wider than the 170mm I have space for. But HEA 140 fits, it is 133mm high. Plus 45-rule + plasterboard becomes about 190mm. That works well!

What should support the HEA beam? HEA 140 at 2.3m weighs only 57kg. Not particularly heavy for two guys either.

 

[justusandersson]

It depends on how handy you are. It works well with columns in glulam or steel. It also works well with construction timber, e.g. 45x145 C 24, if you can fasten it properly in the weak direction.