New sagging roof decking waffer board

Specific Inspection Topics Exterior Inspections
#1

Inspected a 1 yr old roof on an older home. The rear roof decking was replaced by the roofer. There is noticable sagging in the new roof decking.

Both the old and new roof decking is 4’ 8’ Canadian made waffer board or as I call OSB board.

The new sagging roof decking has much smaller strainds of wood chips than the older front decking. There was no rating stamped on this newer decking.

What steps are needed to prove this new roof decking is inferior or under sized for the application?

Is the absence of a rating enough? Do they print ratings on both sides of the boards? Is there a a guide to measure the wood chip fragments and make a guesstimite?

#2

What was the spacing of rafters? Were there H-clips installed between panels? Is the attic properly ventilated? High moisture in winter months may have weaken the product especially if its not rated for roof decking application.

#3

Visual defflection of deck material should be enough to prove the new roof decking is inferior.

CSC,

Appears you have taken the steps

  1. identified deflection
  2. identified absences of identification labeling
  3. identified strand/chip differential (no /guage/guide that I’m aware of)
  4. Need to also know info Raymond asked

Down here labeling for intended purpose must be visible in the attic/crawl. Defect noted in report when I can’t see it.

If and only if your client requests further documentation I’d just report what I see.

Rated Engineered Materials
http://www.apawood.org/level_b.cfm?content=prd_osb_main

Not all engineered material on the market today or in the past is rated or stamped. When I run across it this is also noted in the report.

#4

Craig,

If there’s bowing in the roof field, then it’s obviously missing H-Clips or the rafter spacing is too wide for this OSB material or maybe even in need of mid-span supports.

Is it bowing horizontally or vertically?

#5

Hi. Craig;

[quote=cceccarelli]
Inspected a 1 yr old roof on an older home. The rear roof decking was replaced by the roofer. There is noticeable sagging in the new roof decking.

Both the old and new roof decking is 4’ 8’ Canadian made wafer board or as I call OSB board.
Craig; How could you tell if this Product was Canadian made, just curious.

The new sagging roof decking has much smaller strands of wood chips than the older front decking. There was no rating stamped on this newer decking.
I would think that since the new sagging decking has no stamp, it could not be made in Canada. Maybe Easton, Maine? It would have had a stamp. No stamp, could indicate that it was not intended or designed for this use.

What steps are needed to prove this new roof decking is inferior or under sized for the application?
I would simply note that is no Identification stamp on the new product and might not have been rated for this use of installation and should be further evaluated by a Licensed Contractor.

Is the absence of a rating enough? Do they print ratings on both sides of the boards? Is there a a guide to measure the wood chip fragments and make a guesstimate?/quote)

Not that I am aware of, but that will be updated by someone.

Very interesting topic Craig, and hope someone else will show some light in this.

Marcel :slight_smile: :slight_smile: :stuck_out_tongue:

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#6

If you are looking for the rating stamp try tearing the roof off. I’ve seen too many people put it on upside down with the smooth side up. Stamping is then on top. Need rafter spacing and venalation info.

#7

Its like sod, green side goes up!

#8

Barry, deflection describes the movement experience, i.e. the “floor deflected” when walked on. Sagging describes the condition without movement.

Peter

#9

I cannot count the number of times I have gone onto a building site and seen “this side down” on floor decking. Nothing surprises me anymore. To see roof decking installed upside down is par for the course. After all, the guy is a roofer not a builder.
Larry

#10

As a contractor, I refuse to use OSB on a roof. been there done that. That being said, it sounds like 2 things are missing here. H clips as Raymond stated and the proper thickness of the material. When I framed in Toronto in the 80’s, we used OSB more often than not. On 24’ O/C, H clips are mandatory as well as a minimum thickness of 7/16 ". faiure to adhere to BOTH of these minimum standards will result in noticible sagging of the roof surface within a period of 6-8 months. It’s also a direct violation of the O.B.C. then and now.
Just my 2 cents.