This charming little building has been built hundreds of times, in all sorts of species, with a variety of peg sizes.

I suspect it is forgiving enough to allow the use of 13/16" pegs throughout.

The sizing and location of pegs is a complex and sophisticated engineering exercize that most of us are not qualified to engage in, so we fall back upon traditional patterns.

Get those pegs as far from the end of the tenons, and as far from the edges of the mortised members, as possible.

An impossible balancing act, you say? Made easier by smaller pegs, for sure.

The Guild has been paying for destructive testing of timber joints for years - some results are available on line, and the most recent stuff was published this week in Timber Framing - a benefit of membership.