Comparison of wood cross-section in 2x4 vs timber frame construction.

Comparison of wood cross-section 

2x4 vs timber frame construction

2x4 stud wall

2x4" = 8"sq  (inches squared cross section)

24' span

24 x 12" = 288"       (length converted from feet to inches)

288" / 16" = qty 18 2x4" studs     (16" on center in a 24' span)

18 x 8"sq = 144"sq cross-section in a 24' wall.

8x10 timber frame wall

8" x 10" = 80"sq

24' span 12' on center = 3 posts

3 x 80"sq = 240"sq cross-section in a 24' wall.

Comparison

24'of 2x4" stud wall uses 144"sq

24' of 8x10" timber wall uses 240"sq 

So nearly twice the amount of wood for timber frame vs stud. This supports the axiom that more small connections are stronger than one large one. Airplanes and submarines follow this strategy.

6" x 6" studs

6" x 6" = 36"sq cross section

divided into 8x10 qty 

240"sq (8x10" timber frame qty per 24') 

240"sq / 36"sq = 6.666  

6.666 = (number of 6x6" posts required to equal the same cross section as 3 8x10" posts in 24')

24' x 12" = 288"

288" / 6.6 = 43.63" post spacing (not quite 4' or 48")

divided into 2x4 qty

144"sq (2x4" timber frame qty per 24') 

144"sq / 36"sq = 4

4 = (number of 6x6" posts required to equal the same cross section as 18 2x4" studs in 24')

24' / 4 = 6'  post spacing

Summary

A spacing of 4 feet for 6x6" posts would be slightly less cross-section than using 8x10" posts. (by 10%)

A spacing of 6 feet for 6x6" posts would be the same cross-section as using 2x4" posts. (but we know posts need a higher safety factor)

A post spacing of between 4 and 6 feet is indicated by these estimates. 

A post spacing of 4 feet is recommended for the client's locally harvested white pine timber.

A potential post spacing of 6 feet is indicated as comparable to a 2x4" stud wall, but it must be verified by a structural engineer. There is no safety factor for weak timbers built into that spacing.