How would Cypress Pine be for exterior shed walls?

I'm thinking about extending my shed a couple of metres or so out to the back.



I have access to a site that is being gutted and they have cut out the floor into 4x4' and 6x3' sections for dumping. I can take whatever i want. It's currently Tongue and Groove of course so that wouldn't work too well for expansion, and would need re-profiling (although should be fine as T&G for the internal walls I would think - if it's ok for a floor then should be ok for a wall).



The upper face has got some gluey snotty stuff on it - I presume they glued the carpet down - but that could face into the cavity after I paint scraper it off. I noticed in the rain today that it had gone soft so I could hose it down and then scrape.





So, the question is - how suitable would Cypress be for the exterior walls?



My preference would not be to paint the outside but to use an oil or lacquer that is suitable for exterior.

They are 100mm wide boards, probably 19-24mm thick (i'll have to check).



Also: what would be an appropriate profile to allow for expansion and contraction?