plywood glued box beam in truss roof

[loftwood]

Hi all

Im new here,i have had an enquiry about a loft room conversion in a trussed roof,the person has not had any plans drawn up yet,but he wants box beams constructed to a height of 1.200 to take the weight of the roof and new floor joists.The box beam span will be 4.500 plus bearing on both party walls,also he was asking about the ridge beam to be constructed in timber to take the the new rafters that are bolted to exsisting,he does not want to use steel.

Was thinking of constructing the box beams with C16 timber 9x3 base plate,6x3 top plate,4x3 for uprights and diagonals,and 12.5 wbp ply glued and nailed or screwed.These base plates would have to be spliced,would it be in the middle and bolted?I done these years ago but a lot of work,the only thing is that it is easier to load out than steel.

Would 2 8x3 bolted together be ok for ridge beam 4.500 plus bearing.
He will have to go through a SE and get drawings made up,but i was looking for any information on here,about the construction of the beams and if they will work.

Thanks

Loftwood

 

[Deluks]

Not yer standard question for a DIY forum.
There was a chap around these parts who knew about such things and would give an in-depth answer but he seems to be busy of late.