Originally Posted by seeyou
To the OP:
I haven't read deeply enough to discern whether you've already purchased your OSB or not. If not, try to find Advantech by Huber. It's a few more dollars per sheet, but vastly superior to regular OSB and most plywood that I see for roof sheathing. It's denser and has much better nail holding ability.
OTOH, 7/16" OSB on 24" ctrs meets code in most areas. I don't like it, but I see it on multi-million dollar homes. It will be adequate if installed with clips and nailed properly.
The blocking some of the earlier posters are referring to is adding a 22 1/2" 2x4 between the trusses at the joints in the OSB. Probably little gain for the amount of effort. Use "H" clips between each truss instead. And most of all, be careful up there and don't bite off more than you can chew. Tear off one area, re-sheath and dry-in. Then take off another section and get it dried in. Nothing worse than running out of daylight and energy with an open roof.
oh, and about this. we're using clips and making sure the sheet fall on the truss. nothing seems worse than a big unsupported mass hanging way off a 2x4. my friend was also telling me that we should avoid cutting any sheet smaller than 24" it makes sense too. on the current deck the very worst pieces are the small cuts on top. larger wood has the ability to take on more nails, support itself etc. as for the osb, i picked up a bundle of that LP osb, orange side, white stripe. $9.69 a sheet is why. i considered tracking down the stuff you mention, it's just that spending more is something that would shoot me right over to 3/4" cdx. had i been able to swing it that's what i would have chosen. i have no idea why but the 5/8 and 3/4 cdx is superior in construction to the 1/2. a lot of the 1/2 i checked out was just rough, warped and really light. this 7/16 osb i now have weighs at least a few lbs more per sheet than the 1/2 cdx i picked up. maybe it's just an odd run? who knows.