Originally Posted By: lgoodman This post was automatically imported from our archived forum.
The grain of the plywood sheathing should run 90 degrees to the trusses and it does. For that section of cobbled rafters, the grain is running parallel to the supports and will not perform as well.
I can't estimate the span between the trusses nor between those cripples but I believe the plywood is overspanned in both directions and is not oriented properly for good performance. Allowable span information is printed on the plywood.
Ipredict sagging plywood. Did you walk on the roof? Did it feel springy in this area? If so that would confirm overspannig.
Originally Posted By: lewens This post was automatically imported from our archived forum.
No
It is all wrong. The chimney should be properly headed off and proper rafters installed in the same direction as the trusses The framing members should be at the least 2x6 and the header bigger. This is definately going to fail at some point. Snow loads are significant in Maine and if you get a good snow fall and then a rain, which often happens in Maine, it is going to be loud crash upstairs in the attic time.
Originally Posted By: ccoombs This post was automatically imported from our archived forum.
Ladder blocking or framing is very common when a truss bay is a little wider than the max. 24" o.c. for the roof sheathing. In my area this is mostly at the attic access. The other issue is the spacing of the trusses outside of the two that are caring the load. I should not be more than 72" o/c between the outside trusses. If is more than 72" then the inside trusses are carrying too much load.
In this case it doesn't appear that the trusses carrying the ladder blocking are over loaded. However, it looks like the 2x4's maybe overstressed based on the snow load. I would think it should be calculated. A worst case condition/fix would be to add some additional 2x's and some small hangers at the existing 2x's. The plywood is another issue....
Originally Posted By: Jay Moge This post was automatically imported from our archived forum.
lgoodman wrote:
The grain of the plywood sheathing should run 90 degrees to the trusses and it does. For that section of cobbled rafters, the grain is running parallel to the supports and will not perform as well.
isn't that O.S.B (oriented strand board) so the grain alternates every layer anyway, right? 
Originally Posted By: ckratzer This post was automatically imported from our archived forum.
You could make the grain direction argument. But then again if you look at the alternating plys in plywood you will notice that each plys grain runs perpendicular to the next I don’t really have a point.I’m just whistleing in the wind
Originally Posted By: lgoodman This post was automatically imported from our archived forum.
All sheet goods are to be run perpendicular to framing. This looks like plywood to me because of the distinct grain pattern. Indeed they alternate grains in plywood but some sheets have only three layers. The outside plies always have the grain run the long direction and the sheet gains its full potential by crossing the framing at 90 degrees.
OSB does not have a distinct grain pattern on the surface. It is manufactured with big chips of wood,glued together, with oriented strands embedded in the layers to simulate the strength of wood grain. It is even more critical to run OSB perpendicular for strength but neither is engineered to be installed with the long dimension parallel to the framing.
Originally Posted By: Jay Moge This post was automatically imported from our archived forum.
OOOOOOOOOOOOOOOHHHHHHHHHH. i get it now. my bad. “plywood” has become such a generic term in the feild that some times when they say “the plywood just came in” and you see O.S.B, it just becomes confusing enough not to ask… thanx.
Originally Posted By: lgoodman This post was automatically imported from our archived forum.
I think oriented means “oriented to each other to run like the grain of wood” as opposed to just mixing it into the stew and letting it curl like spaghetti. Oriented to run the long direction of the sheet, parallel to the other strands in the sheet.
Originally Posted By: Jay Moge This post was automatically imported from our archived forum.
dad always called it “waffer board” , boss called it “Ply” and book called it O.S.B. but now i think i gat it. the real reason is 'cuz snakes don’t have armpits…
Originally Posted By: lewens This post was automatically imported from our archived forum.
Curtis
That type of framing may be common but in no way is it right. If the framers in your area do it that way they may be framers but they are for sure not carpenters. No selfrespecting carpenter who was taught properly would own up to that mess. It may not fail where you are in California but in Maine it will, for sure and not too long down the road. How can you expect a 2x4 to hold up what a truss was designed to do?
Originally Posted By: thejnicki This post was automatically imported from our archived forum.
Was thos house/addition home owner done? I could think of a dozen other stronger ways to frame that situation… Looks amateur but we are limited to what we can see in the photos…
I don’t really have a point.I’m just whistleing in the wind 
seriously, correct me if i’m wrong. 
