Black Truss Markings - Redux

daArch

I gotta say, by reading Contractor Talk I was able to answer a question by an electrician yesterday,
"what are the black diamonds for on a tape rule?"
He seriously did not know. Well, I looked real smart when I said those mark every 19.2 inches which is 1/5 of an 8 foot piece of building material.

Well, then the conversation was, "but what does 1/5 of 96 signify?. Where is it used?"

NOBODY on the jobsite knew, well one carpenter said he did, but wouldn't tell unless we paid him. The GC with 40 years experience did not know, nor did the other carpenter, three electricians, four painters, and one paperhanger. I called my brother, he said he knew once but forgot !!!

Last night I looked it up on the internet. All I could find was that it is used for engineered trusses, being stronger, floors and roofs could be spanned at 1/5 of 8'.

Also, this measurement is used with metal sections for use in building stage platforms.

I shared my new found knowledge today. The know-it-all carpenter says that's not it. Well, we shame him into telling. According to an old mentor of his, 19.2 was used in "King's Pine Building". Back in the OLD days, this was one type of building method where studs and joists were 19.2 inches OC.

A number of us were not willing to believe him 100%.

What do any of you know about "Black Diamond Truss Markings" ??

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Wallcovering Installations by Bill Archibald|paperhanger|Eastern Mass|Greater Boston Area|Dover|Wellesley|Franklin|Sharon|MA

neolitic

It's for truss spacing.
I've used it once in 30 odd years, with 1½" T&G decking.

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(Sorry....it seems there really are dumb questions)

K2

I'll take a wild guess. 96"=8"= a sheet of plywood. You save one joist for every 8' by going 19.2 " oc.

K2

It's an everyday event with TJI's. Makes the duct work easier too and a few other things.

L. B. Condulet

http://en.wikipedia.org/wiki/Tape_measure