jonba; if the client has no calcs but still wants some figures, tell him it's dead easy. I did my own for a 3m span in a breakthrough for a kitchen, and here's how.
First of all, I worked out the load. To do this, I weighed one brick and then counted all the bricks in the wall and used a calculator to get the total weight.
I didn't bother about the roof because that doesn't rest on the beam. I wasn't sure about the floor, so I added a bit to be safe.
Then you go to a site called designmyownsteelrsj.com, and it's brilliant!!
You put the load in one box, and the span in another. Then you press "enter"and it tells you what beam you need!!!.
There's boxes with things like gyrations and inertias and things but I didn't understand them, and there was one box which said "plastic modulus" but my beam's steel, so I ignored that.
Anyway, it told me I needed a 610 x 305 x 149kg steel rsj. Well, at
149kg, I assumed 3 of us could lift it. In the end it took 10 of us, so the computer must have got the weight wrong!
Anyway, it's in now. The wife's not too happy because we have to duck a bit every time we go in the kitchen but I told her it's a good strong beam and it won't collapse. If your span is 2.7m, you will need a beam about 15% weaker than mine. So you can tell your client he doesn't need to worry about figures for these things it's so easy! good luck