Foundations: An Achilles Heel for Barns

by Jim Campbell, Duntroon

The lowest floor level of most Ontario barns was used for housing animals whose body heat during the winter typically kept frost from creeping below the barn’s foundation walls and piers.

Interior of a barn with peasants and animals, Giuseppe de Gobbis

The barn builders must have anticipated this symbiosis between animals and building – if not they would likely have extended the foundations below frost level which is typically 4-5′ below grade. I’m sure many of you will know, or have heard, that the downfall of a barn usually starts once animals are permanently removed. The lack of sufficient animal heat permits frost to work its way below the foundations with the resultant expansion of soils causing the foundations to heave, and in so doing, crack or, particularly in the case of rubble stone construction, collapse in part or in full.

The outer wythe of this stone wall has collapsed, leaving the previously unseen exterior face of the inner wythe exposed to the elements.

An exception to frost working its way below the foundation occurs when the barn was built on free-draining gravel or sand which eliminated problematic moisture within the frost-prone depth of soils below … or in some rare instances where manure had been permitted to build up to sufficient depth on the interior and there was ample soil coverage on the exterior to effectively insulate the foundations.

While repairing or replacing portions of a barn’s failing foundation is possible, without the addition of heat or insulation to keep the frost at bay the underlying problem is not likely being adequately addressed. Ideally, if the barn’s lower level is to be unheated, either horizontal insulation is installed around the perimeter (interior and exterior) of the foundations or new foundations are installed that extend below the depth of frost penetration. A combination of some portions having below-frost foundations and other portions not having frost protection is not a good mix since this can result in some areas lifting from frost action while others don’t , thus wracking not only the foundations but the superstructure above as well.

Note the arch of the second tie-beam caused by the heaving of an improperly frost-protected pier foundation below.
As well as deforming this beam, the roof had a substantial hump in it due to this one pier foundation forcing the purlins upward.

The failure of a barn’s foundation can lead to some big questions about the future of the building as a whole. Is the timber super-structure above worth saving? Can the building be relocated onto a new foundation? Is there any historical significance to the building even if it is not a prime example of early Ontario barn construction? For instance, the historic Banting barn in Alliston is currently fenced off for the protection of the public while the Town tries to determine what its fate will be. A failing foundation is a significant part of its problems. Please see ‘May collapse without notice’, Dec. 21, 2021, by The Alliston Herald’s reporter Brad Pritchard:

https://www.thestar.com/local-alliston/news/council/2021/12/21/may-collapse-without-notice-historic-barn-at-banting-homestead-in-alliston-facing-major-structural-problems.html

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