Pole Barn Building
Tom with Sokeri in her new pole barn… Phase 1 of the trinity barn.
Last fall I found myself short a shed. While minding my own business at a local farm checking out a saddle for sale, a bay Tennessee Walking Horse chose me as its person. Sounds odd, I know. It was one of those weird things where, moved by heart and not brains, in an eyeblink she was delivered to my upper field. To top it off, she was with foal. My wife, Carol, had a gelding, and while the two would surely get on great and enjoy one another’s company, the one existing equine residence was a bit cramped for two adult horses, let alone a foal. Luckily, a few months remained to get it together, but I had been forewarned that she had been bred early and would foal very early in the year - a major concern in these mountains where late winter can produce vicious storms and bitter temperatures.
A level area at the west edge of my upper field was ideal for a barn; no excavating needed. Plans soon were drawn for a structure that would accommodate our long term desires, but exceeded our present time considerations. The design was for a “trinity barn” which has a tall center section (this one with an aisle below and loft above) and gable roof, with shed roof sections (for stalls) coming off either side in a symmetrical fashion. Plenty of wide white pine boards already were stacked up here as a chosen siding for several building projects at hand, so they could easily meet the siding needs if only one of those barn sections were built at this stage. There was no framing lumber, however, and with the local mill now out of business, acquiring it was increasingly difficult. The forest surrounding the building site offered easy pickings for long, straight poles of various usable species. Deciding to go with a pole type framing for this structure let the work begin straight away as well as saved the cost of buying and hauling in framing lumber.
The top cross poles of the sides serve as nailers and also carry the load of the rafters. The cross poles are notched into the posts and spiked in place with long galvanized decking spikes. The light is a 12-volt compact fluorescent, powered in that remote shed entirely by solar power.
Rough lumber, log cabins, and timber frames have been a part of working
life since I was a teenager, so there’s a knack for working with
this material I possess over the novice. However, there are just a
few fundamentals to get straight and keep in mind which, with a little
hands-on experience, should get most anybody fairly savvy at building
First, if you have ever built anything with conventional kiln dried, properly dimensioned lumber and other various building supplies of superior dimensional consistency, get yourself a cup of chamomile tea now and accept that "square", "plumb", and "straight" are relative terms in the world of pole construction. This inherent inconsistency is not a huge deal when one gets as close as possible to straight, square, and plumb and combines that gallant effort with coverings that are somewhat forgiving.
Layout for a pole building is like any other. Get a measuring tape and mark out your corners. Make certain to measure to the outside of the post edges, and mark the corners first. Use stakes to mark the outer point of the corners making sure that the distance between each post is correct, and double check for squareness by pulling the diagonal measurements between opposing corners - the diagonals will be the same if the layout is square.
When harvesting poles, try to get one as straight as possible from the get go. Here’s where you will really train the eye. Whenever using them for horizontal positions or rafters, they should be crowned. Crowning is eyeing down the pole (the same thing is done even with dimensional lumber) to find the natural curve present in it, then placing this curve upwards. For reasons of strength, a framing member crowned up will tend to stay strong and only flatten to the effects of gravity, where one crowned down tends to be pulled increasingly towards that center valley, exacerbating the bend.
Once the corners are marked, get out the post hole diggers (the standing joke here being the best use of a Ph.D.) and dig those holes large enough to accommodate the diameter of your posts and at least three feet deep. If you require intermittent posts, it’s easy to set the corners first then run a string line around the outer edge of the corners to determine the exact placement of where the others should go.
One of the greatest blessings in the natural world in this area is the black locust tree. It is the hardest, most rot resistant thing in the forest next to a rock. Cedar is a softer wood, but also has a good rot resistance. These are the only two species I’m aware of with good ground contact rot resistance, so be certain to get one of these for your posts that go in the ground or check out what people use in your area for this. I began by choosing the posts needed and cutting these locusts extra long to allow for any discrepancy.
Rafters go crown-up and are notched bird-mouth style onto a flattened area of cross pole, and fastened with a single spike. Photo by Arika Legg
Sturdiness is necessary for a shed, so I sized my corner posts larger than might really be necessary simply for structural support, about ten inches in diameter at the base, to provide additional ballast. Removing the bark with an axe or draw knife reduces the risk of bugs or rot setting in, particularly in the underground area of the post. A four-foot level laid upright alongside the posts will give you a general idea of plumb, and it is good to shoot for that. I just tamp dirt and rocks into the holes to set them. I prefer to use a small pointed tamp stick, like the end of a shovel handle, with many small shovelfuls of fill put into the hole around the post between tampings. Some people prefer to concrete the posts, which is fine. Some swear by tamping dry concrete mix into the hole; I’ve discovered from pulling out posts done in such a way that the dry mix remains crumbly, so if I were to use the concrete method, I’d at least mix it up with water.
With the posts all tamped in and “plumb”, choose some thinner poles long enough to stretch between them horizontally at top, middle, and bottom. These will serve as nailers for your siding and will tie the structure around the perimeter. At the ground level, again, I use the black locust, especially if the structure is meant to house large animals where muck will be present. However, if you are housing an iron horse rather than a real horse in your shed, or some other inanimate stuff, you may elevate the bottom cross piece around eight inches or so off the dirt and use whatever sturdy poles you have, since rot shouldn't factor in.
The shed here required bottom, middle, and top nailers with the short side averaging eight feet tall and the higher side (where eventually it will meet the central section of the trinity barn) at around twelve feet. The top cross poles on these two sides not only serve as nailers, but also carry the load of the rafters, so I sized them up a bit from typical nailer posts and chose white oak and hickory poles which are strong hardwoods. These cross poles are then notched into the posts and spiked in place with long galvanized decking spikes.
The notching is accomplished by holding the cross pole against the posts where it needs to be permanently positioned. Getting generally level here is a good idea as well. A string line with a small level attached (these can be found at any building supply) can help to get the poles level around the shed. I like to establish the post tops this way, mark them, and then cut the tops with a chain saw to establish the level roof line that is defined by the uppermost horizontal poles. Mark both on the post and cross piece where the notching should be. Notice how wide the cross pole is at the notch area. With the combination of saw, axe, and perhaps chisel that you prefer, remove half the wood from the post and half from the pole so that ultimately the pole ends up flush. When complete, the two should slide into one another. Drive a couple of decking spikes through the pole into the post to secure the joint.
At this point, if the pole is really straight and you have recessed the notches so outer surface of cross pole is flush with outer surface of post, you are in good shape for siding. Often, though, the cross poles and/or the posts are a little squirrelly. In this instance I nail the cross pole in place and then rip whatever wayward edges exist with the chainsaw, or use an axe, to flush out the surface that will receive the siding. Simply sight down along the pole in question and your eye will clearly see large discrepancies in need of adjusting. If such a pole must be positioned where it curves too far to the interior of the building, you may rip a board to fill in the troubling spot and nail it along the pole or post thereby firring it out to flush.
Rafters require much the same consideration. Be sure to crown them. The notches in rafters - where they set onto the top wall poles (called “bird’s mouths” in carpentry) - should be kept shallow as you want to retain as much structural integrity as possible. Flattening out the spots where they rest on the cross pole provides a stable spot for the bird’s mouths to fit onto, but I don’t notch here in the half-and-half deep fashion as on the siding nailers. The rafters are spaced on 3 foot centers, which is adequate as the strength of the hickory and oak pole rafters is plenty to hold roofing even with snow load. If you position the end rafters, at the building’s edge, flush with the horizontal poles below, they can act both as rafters and the top nailer for the siding. A single spike driven down through the rafter pole into the pole below at each notch should suffice to anchor them.
Metal roofing is my preference for pole structures. It easily covers the inconsistencies of the rough poles while looking good. For this type of roofing, purlins are nailed across the length of the roof perpendicular to the rafters. I use two-foot centers going up the roof. Traditionally any old lumber was used for purlins. Here I ripped some of the siding material into three-inch strips for the job and nailed them in place with a couple of 12 d nails at each rafter intersection. If you run the purlins well beyond the roof’s edge, then you can pop a chalk line and trim just where the edge needs to be. You can have whatever overhang you prefer, and can square out the roof exactly, even if the inconsistency from the poles plagued you at the rafter level. Then the metal roofing can go on per manufacturer’s instructions.
I prefer vertical siding, and the aforementioned wide white pine boards
go up quickly and cover well. Other siding types such as metal or horizontal
board also can work. With whatever siding, just keep an eye out for
how the project is progressing, stepping back occasionally to sight
the wall. Make adjustments by trimming or firring out as needed.
When framing a door, I plant a post either side of the doorway. These can be fastened into the top pole above the door area, then to the lower and mid poles. This also provides a sound spot for hinges.
Framing with poles can save hundreds of dollars in lumber costs, looks appealing in a rustic way, and can go up quickly. Coping with the dimensional inconsistencies is the main issue to overcome, but with a little patience, a good eye, and some sharp tools, it doesn’t take long to get the swing of it.
Adapted from "Ponder A Pole Barn ", published in Issue #75 Mar/April 2005 of Back Home Magazine, an excellent hands-on guide to sustainable living - www.BackHomeMagazine.com.