Struggling Building a Garage Maximum 2.5m High

The brickie doesn't like the idea of having a fall visible from the inside of the garage. He prefers a firring above the joists. I was being over cautious with the 1-40 fall as that allows for deflection and errors. To have a 1-80 fall as is the minimum, it's circa 69mm plus 18mm ply so circa 90mm above the joists.

If we ran a universal beam (RSJ) across the middle of the span, we could hang smaller joists. I need to work out what rsj is suitable and I don't know how to calculate this. On the basis building control aren't interested as it falls outside of their remit, we're guessing a bit and reckon a 203 x 133 x 25 should do it with 145x47 joists.

So 90mm down, 145mm joists = 235mm which leaves 2265mm. If I used a 152mm rsj as a garage door lintel (2800mm spanning 2500mm), then that leaves me 2113mm for door height which is what I need there and abouts.

Any opinions on this? I'm trying to not go to our structural engineer as we've had some questionable 'opinions' from him so far.

my thought
remember its above the natural ground level the structure covers not the internal floor level
i would think off sourcing the door first as the frame may be a surprize to the equation
yes the bricky may prefer level and firings but the 50-70mm at the front above the door may be the difference between 2550 fail and 2490pass

The one I mentioned needs less than 100mm, you can see how high up the lintel the frame goes:

Ian H said:

The one I mentioned needs less than 100mm, you can see how high up the lintel the frame goes

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Thanks for the pic. I'll have a look on Byrons website

Somebody needs to let Ian know his vans been vandalised

Notch7 said:

Somebody needs to let Ian know his vans been vandalised

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yes by vanksy by the looks off it

I did it myself, should have torched it