Many of the tapes will also have marks at multiples of 19 3/16+a 
bit.....sometimes used for floor framing.
It's 1/5th of 8', where 16" is 1/6th.....so a 20% savings in joists.

-----Original Message----- 
From: John Tomczyk
Sent: Thursday, April 17, 2014 11:24 AM
To: OldTools@r...
Subject: [OldTools] 16 inch centers

In construction framing (at least here in the USA) standard spacing of wall
studs, floor joists, as well as some other things is 16" on center.

If you frame with 2 X 6 studs they only need to be on 24"centers.
John