We are planning to tear down part of a load-bearing wall and wonder how strong a beam we need depending on the type we choose: I-beam, square beam, or glulam beam. There are rafters (34 degrees) with a span of 5.2 meters and an extension with a sloping roof (9 degrees) that is 2.5 meters where these two roofs meet, we will insert a beam with a length of 4 meters. The snow zone is Piteå 3.0-3.5.
I have assumed that the attic is only used for limited storage. If it is a furnished area, the load assumption must be increased. It still requires quite substantial materials to handle the current load. An HEA 200 (steel beam) or a 90x495 mm glulam beam. You can reduce the height of the glulam beam by increasing the thickness. IPE 240 or VKR 160x160x10 work as alternatives to HEA 200.
When comparing different types of steel beams, one looks at their moment of inertia (designated as I in steel tables). The span is irrelevant in the comparison.
A HEA200 is equivalent to HEB180 then? Both are around 13 in the y-direction and 37 in the x-direction.
But how should one think about, for example, an IPE beam? IPE 240 is "only"(?) at 2.8 in the y-direction but 39 in the x-direction...
A HEB 180 has a moment of inertia of 3831 (x10^4 mm4) and a HEA 200 3692 when bending in the y-direction (the stiff direction). IPE 240 is at 3892. You have to be careful with which type you use and do it consistently, otherwise it's easy to make a mistake. Nowadays, the stiff direction is labeled as y-direction and the weak as z-direction, which is a change from before. I suspect that you have an old steel table.
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