Building a deck, what length wood screws for the support framework ?

Building a hardwood decked area in the back garden. It’s all drawn up and the supporting framework is this weeks job, I’m constructing it from treated 6″x2″ joists. I’ll be screwing through the face of the joist (2″ bit) into the end grain of the next joist to make the frame. How long screws do I need to use ? I’m thinking 150mm but at TVs same time thinking that might be a bit excessive?
Thinking of these maybe ?
http://www.screwfix.com/p/timbascrew-flange-timber-screws-gold-6-7-x-150mm-200-pack/4540j
Might need to treat myself to an impact driver :-)

I used those (and bigger ones) on decking frameworks. You don’t need an impact driver. A decent drill driver whizzes them in no problem.

Better off using joist hangers and twisted nails. Both available from screwfix.
Wood doesn’t like to be screwed into the end grain.

Probably worth pre-drilling through the 2″ otherwise you might ‘pull’ the end grain of the adjoining timber – or have you thought of using coach-bolts and a socket-driver?

And yes, an impact driver is a wonderful tool. :-)