Hi,

Further to my earlier post re windbrace buckling I have just come across a photo of a barn aisle (wall) brace that illustrates how brace buckling and failure can and does take place.

The curved brace on the right has bent out of plane and then fractured in the centre as result of deformation of the whole barn frame. This barn has been rebuilt and reinforced in places (wall plate) and is beginning to show the ravages of time.

Regards

Ken Hume P.Eng.

Thanks for the great photo Ken. Here in the States, I have not seen braces with knots and sloped grain like that. They are usually clear or close to it and straight-grained. Do you know what material we are looking at on the underside of the roof?
Best regards,
Chris Hoppe

Hi Christopher,

The main frame wood would most likley be English Oak (quercus robur) but the rafters might well be an assortment of oak / elm and softwood. This barn is clearly not in its original form with a large down brace connecting the top of the jowl post to the main cross beam now apparently missing. Chances are that this is a reused post from another building. Recycling is not a new concept. The use of branch or low grade trunk material is not uncommon in agricultural buildings. Our views on the acceptability of quality of material today is probably somewhat different from those held by carpenters of yore and even though the wall brace has failed the barn is still standing and could be splinted so clearly the overall performance of a timber framed structure is not necessarily a direct function of individual component quality and performance.

I understand the reasons for employing good qiality materials and if you have them then it makes perfect sense to use them but I do wonder how much more a customer is being required to pay for grades of material that are probably not necessary.

This topic could form a good masters or doctorate thesis for a person with a bent for timber technology and timber frame design with the aim to establish a more practical "overalll fitness for purpose" assessment criteria.


Ken Hume P.Eng.