Hi Christopher, Don, et al,
I was in a 5 bay barn at Ockley in Surrey yesterday and observed that this 18th century barn had been constructed using nearly all "reused timbers" many of which were of much greater antiquity.
One of the major observations made was how both spiral grain and straight grained timbers had been employed for the main jowl posts in this barn with both left and right hand spiral in evidence on separate post timbers.
Up until this moment I had always considered spiral grain timbers to be bad news but I may just have had a change of heart. Where large spiral grained timbers are left fairly intact by the conversion process e.g. boxed heart with some wane, then the checks developed on these timbers tend to be multiple small surface checks rather than one large check through to the heart as per straight grain timbers.
I noticed that the jowl on a straight grained post had developed a huge long check about 5 feet long down a line from where the teazle tenon meets the tie beam and wall plate. This rather obvious and predictable plane of weakness failing was not repeated on the spiral grain timbers where loads are conducted down the grain, rotating as they go and thus tending to prevent an obvious plane of weakness from developing that coincides with the geometry of the piece concerned.
Critical observations are important as is factual analysis when determining best practice.
Mr Phleps arguments may well hold true for log buildings where a rotating timber might lift and entire wall but this might not necessarily be a relevant concern in a timber frame especially where a timber might be free to rotate - e.g. a main post at a barn door which only has mortice and tenon connections on one side.
Regards
Ken Hume
