Removing a beam from plans

[frank999]

I'm thinking of not installing the right hand beam, its only a span of about 1 metre, and the dormer wall will sit on the exsiting wall plate.

Looking at all the loft installations around here that is exactly how they are being put together.

Would I need to trim around the windows with double joists ? to satisfy BC (that isn't what I see though, builders rest two 100x 50 timbers onto of the existing ceiling joists, and use that as a new plate.

Bear in mind the plans below been a approved by building control, would this need justifying by new calcs - how do the other loft extensions know the strength of the old existing lintels - I'm sure their architects dont look at whats there.

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[tony1851]

(I remember seeing this drawing some time ago - its the strange things coming off the steels which stick in the mind).

The beam on the extreme right of the floor doesn't seem to be doing anything - you have a large timber beam directly over the wall plate so why put another steel in?

 

[frank999]

Yes, you all had a laugh at the number of steels in my loft ...
It was the attention to detail, the fixing of the 'straps' you all seemed to like. (shot bolted 'BAT straps' - why called BAT ?).

The attached pictures (below) show I think how it should be done, my concern is the BC inspector, as I wont be working to plans, his concern I guess would be what the lintel above the existing window under this new dormer sole plate can support (on this build it looks like a diryt great big peice of timber (of course devoid of any previous insect infestation )

If he required calcs could I simply trim round the window opening by doubling up the trimming joists.
Does the BC inspector often go on previous experience and what he's seen done before from plans, to judge some works where plans/calcs are not provided, ie can he pass without supporting plans/calcs if he feels confident.

The joist length here from the inner beam to wall plate is very similar (about 1mt), looking at my plans the Imposed UDL is 1.5kN/m2 (about 1500kg per m2) - could I assume roughly half that will be transfered to the ends of the joists - so if the window opening is approx 2mt wide, the loading on that lintel would be 1500kg ?

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