Beam/load-bearing dimension in the ceiling above sliding door section?

[MKna]

We plan to convert an existing "friggebod" into a "uterum"; the friggebod looks like the one in the picture below. The plan is to replace most of the front with a sliding door section (marked in blue). But the question is how thick the beam/header I need to install above the sliding door section to support the roof (marked in red). The front is 4.4m and the gable 3.4m, if possible, we want to install a sliding door section with a width of 3m. How can I calculate this?

 

[justusandersson]

Sliding door units are particularly sensitive to deflection in the surrounding construction, therefore I suggest a 90x360 mm glulam beam. If it wasn't a matter of sliding doors, a 90x270 mm beam would have sufficed.

 

[MKna]

Thank you for the response, but does it really need to be so rough?

 

[justusandersson]

It is a long stretch and you want sliding door sections that are very sensitive to deflection.

 

[Gubel]

It is a long span and you want sliding door sections that are very sensitive to deflection.

Why not a steel beam then? Should handle it at much lower dimensions.