Terrace roofing deflection

Water must definitely not stand on it.

But if there is a raised area in the middle, i.e., at the joint edge of the two beams, water will inevitably stand there.

Hi,

I don't really fully understand this statement here

that with the crossbeams (each 4 m) at the front there is a deflection of 5-6 mm towards the middle now is

but in case you are asking whether your beams are allowed to sag 5-6 mm in the middle over 4 m length:

Yes, they are allowed. Steel construction is usually designed with L/200, meaning under load the beams may deflect by length/200 = here 20 mm.

If you want less deflection, the necessary cross-section (and thus the price) of the beams increases significantly.

However, water should not actually stand at any transition points. That is a source of constant rot and trouble.

Best regards,

Andreas