Hi all:
One more comment on this topic:
It seems to me that the timberframers from years gone by would have used the central post arrangement if it was right to do so, but in my travels I have never seen a timberframe constructed with a central post to carry the load of the rafters in the way described above. The average size of the tie beam across a 30 foot wide barn in the early 19th century was 10" by 12", and upwards, and this was with the purlin posts situated a t 1\3 the distance from the exterior walls. This tie beam was usually supported by one vertical post at its centre. I suggest that such a tried and proven timberframe construction should not be varied from, and might I add that one should err on the side of caution when it comes to sizing timbers to do the job and stand up to the continued stresses from wind and snow loads and aging of the structure down the road. One other thought was the installation of bracing from the top of the purlin posts down to the tie beam would assume some of the outward push of the rafters if installed properly, although this placement of the braces is not necessarily historically correct
NH
