2m 4x2 load bearing

[virgilns]

Anyone know how I can calculate the load bearing capacity of a 4x2 (or multiple 4x2s) - need to provide support for a 300kg water tank over a 2m span with the tank right at one end of the span.

I was thinking 4 4x2s sitting on a 4x2 wall plate bolted to the gable wall in loft and the other end of the 4x2 restting on the party wall...

any calcs I can easily run?

Thanks