Strings for 12-string guitars have gotten so light that I don't believe much beefing up is necessary. Forty years ago everyone knew not to tune their 12-strings up to pitch, but so many players have insisted on it that string sets have gotten very light. It's probably enough to use a standard brace pattern, but not scallop any braces.

It's common practice to build 12-strings with a shorter scale length and twelve-fret necks, both intended to keep the guitar from torquing out of shape. Huss & Dalton follows both practices. And lest anyone worry about underbracing their 12-string, the steel-string books by Sloane and Young both contain material on morphing their dreadnoughts into 12-string models.

At H&D we've made only a few 12-strings and they were on the smaller CM body but without a cutaway. We made everything heavier on the first one, and I knew before I put it together that it would be way overbuilt. Fortunately it sounded OK, though it was quiet. Succeeding instruments have each gotten lighter until we reached the above formula. The red spruce bracing we use is often very stiff, which might make some difference, but I've also seen some brutally stiff Sitka brace stock. I think I'd use the stiffest stock I could find and use a normal pattern rather than use some random stock and try some extra braces with unknown tonal characteristics. We also left the top a bit thicker, and we left that factor consistent while we varied the size of the braces.

There's also the Leo Kottke school where heavy strings are used but tuned way down, perhaps all the way to C. I have no experience with this but would guess that detuned heavy strings would have about the same tension as light gauges tuned to standard pitch. ◆