Sistered joist fastening questions
When sistering a new section of floor joist to a water damaged end of a floor joist, how should the new piece be attached to the existing one? The joists are 2x10 hemlock, 16" on center, span is 10.5', and in a crawlspace. The damage is only to a few inches of the end of each joist.
From searching the web, in the UK, the preferred method is with through bolts or (threaded rod), large square washers, and large nuts. Another UK option is to use something called a Bower Beam - essentially a steel trough made of two L-shaped (cross-section) steel plates that is attached with carriage bolts to the end of the damaged and new joist. Does anyone know a US supplier of Bower Beams?
Many US websites recommend using lots of 16D nails. Others recommend using lots of 3" long deck screws - some say the holes should be pre-drilled. I've also read that all fasteners (bolts, screws, nails, etc.) should be placed a minimum of 2" inches above the bottom edge of the joists. And that if using screws or nails, they should be driven in from both sides - new and old joist sides.
Are through bolts better than nails or screws?
How many is "lots" of screws?
Assuming 3" decking screws, what pattern should be used, i.e. how should they be spaced? Should they be driven in from both sides? Should holes be pre-drilled and, if yes, then what size should the holes be?
Thanks in advance.