This video has me confused. They mentioned two different sphere sizes for testing the balusters. (4″ and 4 3/8″).
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The one sphere is bigger than the other for sure.
Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations
Yup. 4 inches for level rails and 4 3/8 for those on treads. That lets you use two balusters on 10 inch treads.
Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein (or maybe Mark Twain)
"Get off your dead #### and on your dying feet." Mom
"Everything not forbidden is compulsory." T.H. White, The Once and Future King
I never realized that there were two standards! I've always been thinking 4" everywhere. I didn't know about the 6" sphere either so I'm glad that I watched that video.
The IRC code was 4" on both, but they changed it---4 3/8" on balusters going up the stairs ( on open treads ), but kept it at 4" on level and guard railings ( balcony ). Caveat: Depends on what your local codes are , i.e.- in my state ( Fl. ), new code won't change till sometime in OCT., so right now it's still 4" and 4".
On the 2 baluster on a 10" tread thing--if you are using 1 1/4"pin top balusters-- that works out to exactly 4 3/8', I would go with 3, no sence having 0 wiggle or opps room. on a 9 3/4" tread -- no problem. With 1 3/4" balusters --no problem on a 10" tread.
Roger