Farming Magazine - May, 2012

FEATURES

Re-Engineering the Pre-owned Barn

News uses for old structures
By Martin Harris Jr

There's a lively market in ancient heavy timber barn frame components carefully and expensively salvaged and enjoying second lives as exposed timbers in high-end residential housing designs.
Photos by Martin Harris Jr.

If it's at all well-built, most construction physically outlasts its first owners/occupants, and subsequent users may have different functional requirements for which the building can be adapted. If it can't, it will probably be cannibalized, which explains why there's a lively market in ancient heavy timber barn frame components carefully and expensively salvaged and enjoying second and quite new lives as the artistically exposed timbers of multiple high-end residential housing designs. Old buildings can frequently be adapted for new requirements, which explains why a lot of late 19th and early 20th-century residential design books showed floor plans without interior bathrooms, and when you inspect the actual houses today, they all have that recent amenity. My grandfather's standard cookout time joke - "In my day, folks went to the bathroom in the backyard and ate dinner in the house, and now you folks do just the opposite." - contained just that kernel of historical truth.

Similarly, many of the then-standard dairy barn designs of the post-World War II decade - the last fairly long time block for industry profitability - now no longer suited to a different scale and mode of livestock management and milk production, have been adapted to a different set of ag-related uses. Any large building with a sound frame and roof can be adapted, with or without a little demolition, for crop or equipment storage. So, the more interesting cases are those where the former dairy barn for about two dozen milkers is now the beef barn for about two dozen steers, as exurbia expands into former farm country and there always seem to be enough part-timers or retirees or weekenders eager to make good use of the (sometimes barely) surviving structures. Across the nation, there are lots of these in gently rolling hill country, areas more suitable for traditional low-intensity pasturing than for modern high-intensity grazing or cropping, which explains why you're just as likely to see these three-cow-aisle barns (two under the main roof, one under a newer lean-to addition on one side, with a connected 10 or 12-foot-diameter wood or concrete silo on the other side and an add-on milk room at one end) in the Appalachian foothills of western New England as in the Appalachian foothills of eastern Tennessee. It was a design that worked well for dairy operations, and works just as well in terms of livestock movement when the three-aisle design is used for the feeding and weather-shelter functions for beef, but doesn't work quite as well in two design areas: structural and ventilation.

The structural concern arises because small-scale beef is rarely a daily-labor operation, and therefore such barns almost always become manger operations with clean service aisles but bedding pack livestock floors, and therefore with fairly constant chemical reaction between corrosive manure elements and the steel (in a few cases, wood) columns carrying the major girders that support the joists of the haymow floor above. Unless the internal columns (and the exterior walls, too) are protected from the manure-heavy bedding pack, serious damage will quickly take place. The farmers who raise beef and address this issue (about half, I'd guess) do so with concrete about 2 feet high, replacing the column bases and protecting the inside faces of the exterior walls. Depending on the original manger design, some concrete may be needed there, too, to keep the feed clean and at the proper feeding height. Under the bedding pack, a few beef operators fill in the original manure gutters with concrete; most don't, and I've not yet seen one operation that installed a new slope-to-drain floor, or, as in new freestall operations, an automated livestock aisle floor scraper.

The ventilation concern arises primarily in colder climate zones mainly because of haymow (non) use, and focuses on the moisture condensation question that is always present where livestock are housed for whatever purpose. In their original design and use, these tall barns had loose or square-baled hay storage over the entire cow stable beneath. The stored feed served as effective insulation, keeping the stable ceiling as warm as the heat gain from livestock minus the air changes from window or fan ventilation could make it. In a traditionally operated stanchion barn with a well-filled haymow, a visitor never saw a cold stable ceiling with water vapor from cattle or manure condensing on it. On windows or uninsulated walls and doors, yes, but on warm stable ceilings, no. The same for the steel exhaust fans and housings installed and operated after the arrival of rural electricity during the Depression years, where the rust shows the condensation on the cold steel when the fans aren't operating. Same for the vertical wood-boarded stale-air exhaust chutes operating on the warm-air-rises principle, installed during the 19th and early 20th century. Near the top, where they rise through the haymow, the water stains show the point above the haymow floor penetration where the moisture-laden air chilled enough to reach 100 percent relative humidity and condensed, in severe cases enough to run back down into the stable below. In modern use, haymow floors aren't frequently piled with heat-conserving hay.

That's why such cold-ceiling conditions in the stable below are now just as prone to moisture condensation when the livestock are indoors during cold weather, as are the exposed steel underside of modern roofing for freestall or loafing barn construction. The cure, where hay can't be used, is the same as for any modern commercial construction where fairly low indoor temps are OK, but indoor "rain" isn't: keep the stable ceiling at least warm enough so the air that hits it isn't chilled enough to reach its own dew point and shed its moisture load in the form of condensation. Usually a modest amount of insulation, and a vapor barrier (typically some form of low-perm-rating sheet or board plastic) is enough to keep the indoor airborne moisture from getting deeper into the insulation, where the temperature slope-line between warm indoors and colder outdoors has dropped enough that condensation would happen if moisture were available. Such ceiling designs are much easier to install and maintain than similar wall designs in livestock housing, but cattle-damage-proof systems are available. Interesting side note: for low-slope no-overhead-haymow contemporary livestock housing, retained roof snow can furnish some useful insulation, but the older barns were designed with roof pitches that don't require shoveling.

The older barns were designed to be operated as total-enclosure structures, with the engineering implication that exterior wind loads were to be designed for, but interior wind loads wouldn't exist. That's in contrast to open or even semi-open structures like contemporary freestalls and loafing barns, and equally in contrast to older barns similarly renovated. If you recall news accounts of buildings that sustained hurricane or tornado wind loads only until the doors or windows failed, you can visualize the engineering principle: for enclosed buildings, only exterior wind loads, positive and negative, need to designed for; but for open-front or similar structures, the wind pressure on the inside - most critically, the underside of the roof - must be added in. Interestingly, a recent and detailed discussion of engineering problems involving large doors in modern ag construction, published in Frame Building News, focused on the wind load question for the door surface and not on the question of building interior wind loads when doors are open during a high-wind event. How the new owner uses his old building - open or closed operation - will determine how much attention he should devote to this engineering question. There's another roof engineering question he'll want to address, irrespective of the open-versus-closed operation question.

It traces back to the traditional roof design for tall barns in the 30-by-50-foot size range: paired rafters, with or without a ridgepole at the upper end, each rafter-foot bearing on the top of the side wall plate girder at the lower end. About half of such structural designs had (have) no collar or tie beams to help neutralize the outward thrust caused by roof live loads (wind and snow) and dead loads (structure and finish) transmitted down the rafters to the plates. The old framing standards called for heavy timber cross girts installed just below the plate level performing under horizontal tensile loading to prevent the walls from leaning out under such pressure, but in many cases they've been cut by owners or damaged by roof leaks. If you can examine a recently failed old tall barn in the midsize range, odds are you'll find evidence of roof collapse as the restraints against outward rafter movement became inadequate. In smaller and larger buildings of similar vintage you'll frequently find the design solution: columns rising through the haymow to support the ridge beam, or the rafter pairs near the ridge. It's a design that prevents sagging of the roof ridge, and thereby reverses the horizontal component of the rafter load on the plate; with columns in place, the rafter tops are fixed in place vertically, and the bottoms, if unrestrained for any reason, would want to vector inward, not outward, under load, and usually there's enough interior construction for easy resistance of such inward pressure. Installing such columns, if the building seems to need them, is an easy and inexpensive remedy. The only downside is a bit of physical obstruction in the haymow space. Of course, pre-owned barn owner wannabes can't always find used barns, which explains why there's a thriving market for same-size new ones. These are typically framed differently: with poles, girders, roof trusses and at-grade floor slabs, often with open or semi-open design, and not often with overhead feed storage. They have their own sets of problems. Some, like wind loads, were partially described above; others, like the differential structural movement which happens when severe frost gets under the slab but not under the deeper pole footings, were not. Those subjects alone would fill a whole 'nother feature.

Check Out These Building & Construction Resources!

Company Contact
AB Martin Roofing Supply www.abmartin.net
ACR Metal Roofing www.acrmetal.com
Alternative Heating of North America www.ahona.com
Bauer Concrete & Masonry, Inc. 315-465-4021
Center Hill Barns www.centerhillbarns.com
Central Boiler www.centralboiler.com
Conestoga Buildings www.cbstructuresinc.com
Elitsac Lumber www.elitsac.com
EPS Buildings www.epsbuildings.com
Essex Structural Steel Co. www.essexsteel.com
Farmtek www.farmtek.com
Fish Associates www.fishassociates.com
Flexospan www.flexospan.com
Ken's Farm Market www.kensfarmmarket.com
Keystone Concrete Products www.keystoneconcreteproducts.com
Lester Buildings Systems www.lesterbuildings.com
Mac Hyney & Sons www.wefixsilos.com
Millbrook Farm Woodworks www.millbrookfarm.com
Mountain Air Garage Doors www.mtairgaragedoor.com
Mud Lake Stalls www.mudlakestalls.net
North Country Storage Barns www.ncsbarns.com
Perma-Column East LLC www.permacolumn.com
Pioneer Pole Building www.pioneerpolebuildings.com
Quality Products & Supply, LLC 717-355-7112
Robinson Concrete, Inc. www.robinsonconcrete.com
Varco Pruden www.vp.com/ad/Farming
Willow Road Silo Doors 717-394-1004

The author is an architect and former farmer.