OSB vs Plywood for Roof

[hawkeye08]

Daughter and SIL building a house, roof trusses on 24" centers, 5/8 plywood for the sheating, spec'd by truss company to achieve the 70lb snow load they need.

 

[BoylermanCT]

Building a wood shed and am using 1/2 OSB for the roof decking. Lumber yard tried real hard to talk me out of $9 OSB and use $20 plywood or $25 zip board. Said no one uses OSB for roof decking.

 

[finn1]

Inspector made us use 5/8” osb and trusses 24” OC. The trusses have to be engineered for local snow loads... 300” last winter.

Literally no one uses plywood here.

 

[RickB]

Building a wood shed and am using 1/2 OSB for the roof decking. Lumber yard tried real hard to talk me out of $9 OSB and use $20 plywood or $25 zip board. Said no one uses OSB for roof decking.

Regardless of what anyone thinks of OSB, saying it isn’t used for roof sheathing is just plain wrong. The house we built in NY in 1989 had OSB all the way around. We sold it in 2017 with the original shingle roof and siding. The house we bought in NC was built in 1992 and has OSB roof sheathing. I’m not losing sleep over it.

 

[LittleBill21]

what are the clips for? expansion and contraction?

i bought some osb for a interior project, everyone mentions how bad it soaks in rain, i left a cut piece on a wood pile and it got rained on for 2 months, it barely and i mean barely had any issues on the cut edges and 0 on the main section. i expected it to disintegrate in the first rain storm

 

[RickB]

And when radial tires first came out they were no good either.

 

[aczlan]

what are the clips for? expansion and contraction?

i bought some osb for a interior project, everyone mentions how bad it soaks in rain, i left a cut piece on a wood pile and it got rained on for 2 months, it barely and i mean barely had any issues on the cut edges and 0 on the main section. i expected it to disintegrate in the first rain storm

Clips are to keep the edges aligned (vertically), with 24"OC trusses, you would place a clip halfway between each truss. That way if someone steps just above or below the seam, the clip helps spread the stress to both sides of the seam.

Aaron Z

 

[3Ts]

Clips are to keep the edges aligned (vertically), with 24"OC trusses, you would place a clip halfway between each truss. That way if someone steps just above or below the seam, the clip helps spread the stress to both sides of the seam.

Aaron Z

In addition to that, each sheet is supposed to have a small gap between the next one. The clips provide that spacing.

 

[Tomtint]

Unless you go with a quality OSB like AdvanTech and compare it to run of the mill big box hardware store plywood.

I've gotten plywood from Lowes and Home depot that delaminated slightly, then when I look inside there were massive voids. So on 5 layer plywood I would find a "decent" surface layer, a voidy second layer, etc. Sometimes a "knot" on the surface layer would line up with a void underneath.

OSB is solid when made and I've seen the AdvanTech sit out in the rain for months. But the darn stuff is HEAVY. Unlike PT plywood it does not get lighter with age.

"Old timy" OSB used to crumble quickly. Throw a fresh piece off the porch in the rain and it would crumble before it hit the ground

AdvanTech is my go-too for sub flooring. It's a fantastic product. Up here the buzz has been Zip Wall... I'm not sold on it. You need to be very careful while nailing it not sink the nails too deep. Long story short, my parents house was built on the ocean in the mid 70s, if was build pre PT lumber code but was build with plywood and sided with tar paper / cedar shingles. Roofed with tar paper/ 30 year shingles. We did a remodel on it 10 years ago. New roof, siding, windows, trim etc. stripped all the old material.. Tar paper was perfect as was the plywood. ... Again, this house is on the ocean and had 30+ years of being beat on by salt spray etc.

 

[Bigkrank]

And when radial tires first came out they were no good either.

When plywood came out it, some was no good either. Some was good but got cheapened up after it was out awhile. On my first house the builder made us use 1 X 12 boards diagonally for roof sheeting. Floors were boards also. He did not allow one sheet of plywood in the whole house. He hated the stuff.