flat roof load on 4m lintel

[stevetgs]

hi

i am currently slowly building a 6060 x 4000 extension, brick @ block and would appreciate any help and advice.

could any one help calculate the roof load.specified as -

50x170 C24 @ 400 centres

12mm ply on firrings to falls

115mm celotex

6mm external ply

3 layers felt


also, whilst trying to be in keeping with existing building i would like to have full height doors and windows (to roof height) which therefore would leave me a span across the front of 6m with an 'opening' of 4m for glazing. i would like, if possible to span this with wood and joist hang off of it. what would be best to use for this? C24 bolted together? solid bean? flitch beam?

i am trying to research as much as possible but finding answers hard to come by.

any help is much appreciated.

 

[tony1851]

Working on a dead load of around 0.7kN/m2 and live load 0.75kN/m2, and a clear span of 4m, two 2x9s C24 firmly fixed together would do.
Deflection under max. load would be around 1/2".

 

[stevetgs]

thank you tony.building control visit today so see where i stand.