H-clips - required?

[Joe Funderburk, CMI]

Originally Posted by jfunderburk

Bruce, if the live load maximum for 7/16 at 24" OC is 40 lbs/sf, how could anyone but a child walk on it? Seems like there could be no walking whatsoever on such a roof.

Anyone know how the weight of a person is distributed on a roof? For example, how is the weight of a 200 lb man distributed on a roof per sq. ft?

Where do they come up with 40 lbs/sf max on live loads? Wouldn't that necessarily prohibit anyone from ever re-roofing the structure?

I got an answer to that the question above today. Loads are calculated as being distributed over the entire roof. A "point load", of say 200 lbs., is not calculated or addressed anywhere in the IRC and you don't have to design a roof to accommodate temporary point loads.

[Kenton H. Shepard, CMI]

Originally Posted by jfunderburk

Kenton, I beg to differ. It most certainly IS a code requirement. See: IRC 2009 (and 2006) Table R503.2.1.1(1). How can you say it isn't a code requirement when it clearly specifies the need for end supports (clips being the most commonly used method) in the IRC???

Anyone installing 7/16" OSB or plywood on 24 inch spans without end supports (clips) is in violation of "commonly accepted building standards" (the IRC) unless your jurisdiction has chosen to exclude that requirement by law.

Some ran off with the office copy of the IRC, Joe. I was talking from experience, having installed roof sheathing without clips on many, many homes in CA and CO when the jurisdictions in those states used the UBC.
But I've been out of the trades completely since about 2003, so it was probably introduced as a requirement in the 2006 edition IRC.

Anyway... it's still too close to being a code call for me to call during an inspection. Correction would consist of blocking every joint in the roof. If there are a couple million homes sheathed with OSB/plywood with no clips (and there are at least that many) and no failure as a result, how can an inspector justify recommending an expensive correction. My feeling is... if it ain't broken, don't fix it.

[Joe Funderburk, CMI]

Kenton, what if it was a new home?

[Kenton H. Shepard, CMI]

State that it's not a code inspection but that the building code under which the home was built required installation of h-clips which are missing on the home inspected. State whether or not you saw failure that appeared to be a result of the omission. Recommend evaluation by a structural engineer and let him make the final recommendation.

That way you call attention to a code violation without taking on the responsibility for identifying all code violations and you pass on the liability to the engineer. You look good because you did your job, didn't miss it, and didn't endanger the transaction.

Realistically... the engineer will say it's OK, no one's stressed or out a lot of money over a relatively minor omission, and everyone involved recommends you for future work.