Thread: Compare these two roofs..Prosper Texas

While inspecting the roof of a new-buildhome, I noticed the roof on these two adjoininghouses. Look at the roof on the house on the right. You can see the outline ofthe 4x8 OSB sheathing on the house on the right, but not on the left. Bothhouses were built by the same builder, within weeks of each other. I can only guess they used a differentunderlayment on the left house, or left it out maybe on the right house. Notsure because like I said, I was not inspecting these houses, I just noticedthem across the way. I see the outline of the sheathing from time to time whendriving through new neighborhoods. Anyone care to comment on what is happeninghere?

The photo is taken from the roof of the house I was inspecting.

Gene

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Clips on the Left

No Clips on the Right.
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Originally Posted by Billy Stephens

Clips on the Left

No Clips on the Right.
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Clips are not required - spacing is.

Originally Posted by Jerry Peck

Clips are not required - spacing is.

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That's What Correctly Installed Clips Give You.
* and some other benefits

Thanks Billy.

Gene

Originally Posted by Billy Stephens

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That's What Correctly Installed Clips Give You.
* and some other benefits

I know, but ... you are not required to use clips, and if you were to use THICKER plywood ... ... and not that el cheapo 3/8" crapo ... something like 5/8" ... then you don't need clips - spacing yes - so you can use 16d nails as spaces (you just need to remember to pull the nails out after the plywood is tacked in place, otherwise you will have a "shiner" nail which will work up and cause a leak).

Here's a fairly recent thread about a similar effect.

Do you happen to know if there was any rain around the time they were decking and roofing?

Originally Posted by Jerry Peck

I know, but ... you are not required to use clips, and if you were to use THICKER plywood ... ... and not that el cheapo 3/8" crapo ... something like 5/8" ... then you don't need clips - spacing yes - so you can use 16d nails as spaces (you just need to remember to pull the nails out after the plywood is tacked in place, otherwise you will have a "shiner" nail which will work up and cause a leak).

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That was never Stated .
* except by you.

Originally Posted by Billy Stephens

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That was never Stated .
* except by you.

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*I* didn't state clips were required.

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You stated that the cause was the lack of use of clips

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Originally Posted by Billy Stephens

Clips on the Left

No Clips on the Right.
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The lack of use of clips has nothing to do with what is shown.

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The lack of spacing has to do with what is shown.

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I've seen many clips which do not provide the required 1/8" spacing, more like 1/16", and then the plywood sheets are driven down snug against the clips and there is no spacing.

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Billy, you need to get your facts right - otherwise you just make yourself look foolish with the large bold font.

Originally Posted by Jerry Peck

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*I* didn't state clips were required.

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You stated that the cause was the lack of use of clips

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The lack of use of clips has nothing to do with what is shown.

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The lack of spacing has to do with what is shown.

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I've seen many clips which do not provide the required 1/8" spacing, more like 1/16", and then the plywood sheets are driven down snug against the clips and there is no spacing.

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Billy, you need to get your facts right - otherwise you just make yourself look foolish with the large bold font.

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Then " The Clips" Are Not Installed Per Manufacturers Installation Instructions.
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Just what are the mechanism and effect of not having the 1/8" spacing?

And I don't get it - they talk about tongue-in-groove as being an edge support, but that is mutually exclusive of any spacing. Hmmm, maybe not, if the joint's not fully closed.

It takes quite a rise to make such obvious lines as are shown here, and it's very consistent.

Is the sheathing Solarboard or a similar product by any chance?

Originally Posted by Kristi Silber

Just what are the mechanism and effect of not having the 1/8" spacing?

Materials expand and contract. If the sheathing is butted together tightly there is no room for expansion within the plane of the panel, so it expands perpendicularly to the plane at the edges.

And I don't get it - they talk about tongue-in-groove as being an edge support, but that is mutually exclusive of any spacing. Hmmm, maybe not, if the joint's not fully closed.

Exactly. The tongues and grooves are cut such that there is typically a gap between the panel edges. You still need to ensure there is a sufficient gap between the butt ends of the panels though.

Originally Posted by Corn Walker

Materials expand and contract. If the sheathing is butted together tightly there is no room for expansion within the plane of the panel, so it expands perpendicularly to the plane at the edges.

Since this is a new house, it doesn't seem the panels would have expanded and contracted so much that the results would be this obvious, unless the house was sheathed during a particularly cold period. It's also very uniform, with problems on horizontal and vertical edges. From the evidence I would guess that it got rained on just before it was covered.

Originally Posted by Billy Stephens

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Then " The Clips" Are Not Installed Per Manufacturers Installation Instructions.
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NONETHELESS ... ... THE CLIPS ARE NOT REQUIRED.

Jerry, how can you know without knowing the rating of the sheathing and the rafter span?

Originally Posted by Kristi Silber

Jerry, how can you know without knowing the rating of the sheathing and the rafter span?

Because ... ... like Billy implying that clips are needed (implying 'in all cases'), the opposite of that is to state that clips are not required (implying the same reference of 'in all cases'). Clips are not required 'in all cases' - in some cases clips may be required, but I am responding to a set-in-stone-statement without any qualifiers, thus my statement is the same to the same inference.

Besides, the "rafter span' has nothing to do with it. (Think about that a minute and you will understand what my response is referring to.)

Originally Posted by Jerry Peck

Because ... ... like Billy implying that clips are needed (implying 'in all cases'),
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the opposite of that is to state that clips are not required (implying the same reference of 'in all cases').
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Clips are not required 'in all cases' - in some cases clips may be required,
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. but I am responding to a set-in-stone-statement without any qualifiers, thus my statement is the same to the same inference.
)

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Thus , Shush
* and some of that thrown in.
** UH Thanks for Clearing that Up.
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It didn't take me a minute to figure out what was wrong with "rafter span." You're right, wrong phrase. Why can't you just say, I think you mean "X"?

And you're picking on my word choice when you think it's reasonable to counter an implied meaning with a false generalization in order to carry on a silly argument that has nothing directly to do with the OT?

Originally Posted by Kristi Silber

Jerry, how can you know without knowing the rating of the sheathing and the rafter span?

I'm not Jerry, but in general...

For rafters spaced 16", panel edge support isn't required for any panels rated 20/0 or higher. I'm not aware of a panel on the market with a lower rating. (and any builder using such a panel should have their license revoked, their air hoses cut, and their truck keyed)

For rafters spaced 24" or greater, panel edge support isn't required for any panels rated 24/16 or greater.

This means H-clips (or other panel edge support such as solid blocking or tongue and groove) are only required for rafter spacing greater than 20" with sheathing rated 24/0 or lower (unless other design requirements dictate such as those in 2306.3.1 and 2306.3.2).

Typically this means only panels 3/8" or thinner with rafters spaced greater than 20" will require panel edge support. I know contractors cut corners, but I'd be surprised if the houses pictured specified what is essentially the minimum design possible. In my area the supply houses don't even stock 24/0 panels; the minimum is 24/16 (7/16" nominal) and more common is 32/16 (1/2" nominal), 40/20 (5/8" nominal), and 48/24 (3/4" nominal).

Originally Posted by Corn Walker

I'm not Jerry, but in general...

For rafters spaced 16", panel edge support isn't required for any panels rated 20/0 or higher. I'm not aware of a panel on the market with a lower rating. (and any builder using such a panel should have their license revoked, their air hoses cut, and their truck keyed)

For rafters spaced 24" or greater, panel edge support isn't required for any panels rated 24/16 or greater.

This means H-clips (or other panel edge support such as solid blocking or tongue and groove) are only required for rafter spacing greater than 20" with sheathing rated 24/0 or lower (unless other design requirements dictate such as those in 2306.3.1 and 2306.3.2).

Typically this means only panels 3/8" or thinner with rafters spaced greater than 20" will require panel edge support. I know contractors cut corners, but I'd be surprised if the houses pictured specified what is essentially the minimum design possible. In my area the supply houses don't even stock 24/0 panels; the minimum is 24/16 (7/16" nominal) and more common is 32/16 (1/2" nominal), 40/20 (5/8" nominal), and 48/24 (3/4" nominal).

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Span Tables Page 3 ( taken from Post 4 )
* No One Except Jerry is Implying The Requirement or No Requirement of Clips.

I see, as many inspectors, a serious amount of shearthing from the underside.

What I see or should I say, don't see, is spacing at all. About never. What I find is that the sheathing exposed to moisture as in wet, not just humid, the sheats swell and the edges get puffed up from the swelling and pushing against one another. If it is dry and the roof system gets complete I di not see this at all.

Yes. Spacing is required to keep this from happening. The in case, it gets wet before covered. The clips? How true it is. Less spacing of the rafters and some actual thickness to the sheathing and you don't need them.

The end result Gene is that the sheathing needs spacing to help prevernt this (and to prevent bowing/sag between the large spacing of the rafters). That spacing with out clips almost never happens.

Originally Posted by Billy Stephens

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Span Tables Page 3 ( taken from Post 4 )
* No One Except Jerry is Implying The Requirement or No Requirement of Clips.

From Billy's link,

7/16 plywood used for roof sheathing on 24 inch center supports (rafters or trusses), without edge support (without clips), span = 24 inches; with edge support clips, span = 24 inches ... ummmm ... no clips required.

15/32 (1/2") plywood used for roof sheathing on 24 inch center supports without edge support (without clips), span = 28 inches ... no clips required.

Now, if one were to try to build a wrestling match ring and trampoline with the use of 3/8" plywood, you would be required to use clips for 24 inch on center supports, but, I suspect those clips could become a bit dangerous to the guys (and gals) who fall or are thrown down to the mat ... no wonder some of them come up bleeding.

If one were to use 3/8" roof sheathing ... they deserve what they get and see!

Originally Posted by Kristi Silber

It didn't take me a minute to figure out what was wrong with "rafter span." You're right, wrong phrase. Why can't you just say, I think you mean "X"?

And you're picking on my word choice when you think it's reasonable to counter an implied meaning with a false generalization in order to carry on a silly argument that has nothing directly to do with the OT?

Kristi,

My apologies, I guess I thought I was responding to one of Billy's posts. He was starting to get as bad as Watson on that larger bold text thing.

Originally Posted by Jerry Peck

Kristi,

My apologies, I guess I thought I was responding to one of Billy's posts. He was starting to get as bad as Watson on that larger bold text thing.

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Just Trying to be Helpful.
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