Carport span

Hi all. I need to build a carport 5m x 5m with only 4 posts (1 each corner). Will 240 x 45 F7 be sufficient for the beams, which will be around the whole of the carport with rafters across the middle . Im thinking i will have to run a another 240 x 45 F7 beam across the middle to reduce rafter span. I have looked at 2 span tables and they tell me differant things. It seems to be borderline. Should i go to 290 x 45 F7?....? N.B. Flat roof (with 5-10 degree fall) and colourbond roof. Low wind area. Cheers guys

The best thing to do would be get hold of the Allan Staines Carports book, which will give all the span tables and tell you how to put it all together. :)

Or http://www.timber.net.au/documents/#DIY might help?

I know its a woodwork forum but what about some nice steel purlins for a flat carport or a nice gable trussed in timber. I think these would work out a bit cheaper.

Cheers
Pulse