Post & Beam: A Centuries-Old Building Technique Creates Beautiful, Energy-Efficient Homes:
Homes & Cottages Magazine
The great cathedrals of Europe have stood for hundreds of years. Huge, bulky wooden ships have survived horrendous storms. For decades, flimsy-looking barns have withstood tough Canadian prairie winters.
What these structures have in common is post-and-beam construction. Also known as ‘timber-frame construction’, post-and-beam uses a framework of strong timbers. In the ship-building example, the framework was of a dense wood such as oak, and the timbers were connected with mortise-and-tenon joints. In this system of joinery, a mortise (or slot) was chiseled into a beam at the point where the joint was required. Then, the end of the post was chiseled to make a tenon fit tightly into the mortise. A hole was drilled through both mortise and tenon, then a tightly fitted wooden peg was driven through the two pieces to lock them into a strong joint that would not fail under stress. When the framework of the ship was joined, thick oak planking was attached with wooden pegs to the timbers of the ship’s frame.
When applied to residential construction, the post-and-beam method has posts that extend from the foundation to the ceiling, connected by beams to create the frame, which is then enclosed by exterior cladding. With posts and beams supporting the structure, none of the walls between the posts are load-bearing.
When you don’t have to worry about having walls to support the ceilings or floors, and strong timbers can be used to span wide spaces, you end up with unlimited design flexibility. Ceilings can soar to any height and rooms can be as large as your lot allows. You can have many windows of any size. Hide the wood entirely, with paint or dry-wall, or leave some, or all of it, exposed. If the wood is left exposed, the framework adds attractive geometric patterns to the décor. It can make for a darker interior, but the tone is warm, and that improves with age.
Another advantage of post-and-beam construction is strength. Post-and-beam houses can survive anything but fire. In parts of the world hit by earthquakes and hurricanes, the post-and-beam buildings are often the only structures left standing. This tremendous strength also stands up to heavy snow and wind loads, making post-and-beam homes the ideal choice for regions which experience extreme weather conditions.
Alex Ross, president of Surrey B.C.’s Canadian Custom Homes, says the strength and durability of a post-and-beam house is a reason for the growing popularity of this type of construction. “With a regularly built home, the walls are in the first to go in an earthquake. The ground shifts, the walls move, glue breaks, nails loosen—if it stays standing, the wall is weakened. Because the walls support the house, if the wall strength is compromised, the house has to be dismantled.
“Post-and-beam houses are made of engineered posts and beams held together with metal brackets. The posts are permanently erect. This makes for extreme rigidity and very little movement. If a hurricane or earthquake hits, a post-and-beam house could lose a wall, but the structure should not be compromised. All you have to do is replace that wall section. So there’s really no reason why a post-and-beam home can’t last forever.”
Post-and-beam construction can also be more energy-efficient. It is more air-tight and there is no limit to the amount of insulation that can be added. Since post-and-beam homes normally have high vaulted ceilings, fans circulate heated air as it rises, ensuring even temperatures.
Ross says a post-and-beam home can look like an ordinary house. “Most of what we do is a post-and-beam framed interior with 2x6 framing, which is insulated, then faced with siding, stucco, rock or brick. Design-wise, you can do literally anything you want. If you don’t want any interior partition walls in your home, you don’t have to have any. You can use logs to fill and face the frame so your home looks like a log cabin. You can have high vaulted ceilings with loads of glass windows and skylights. That increased light and openness is something that many people find very appealing—it makes the smallest house seem large.”
Normerica president David McFarlane says that, among this customers, the main reason for the choice of a post-and-beam home is the aesthetic appeal. “The post-and-beam look makes a statement. It’s exciting to look at. None of our customers cover their wood—they want that honest appearance, the smell of the wood and the elegance of the design.”
When designing a post-and-beam house, it is worth remembering that you can change the design after it’s built—as long as you put the posts in the correct position when the foundation is built. Because walls between the posts are not load-bearing, a partition can be removed at any time and put somewhere else. So if you want to turn two bedrooms into a games room or large office, it is easily accomplished.
Technically, you can build your post-and-beam home out of just about any hard wood, but the most common woods used are Douglas fir and Eastern white pine. There are few differences between the two—the selection depends on which company you buy your home from. The foundation of a post-and-beam house can also be wooden, if the property has good slope and draining, but concrete slab foundations are most common in Canada.
Two of the largest suppliers in North America are Canadian companies—Lindal Cedar Homes and Normerica Building Systems. Lindal, despite its name, uses cedar for siding only. It does its own logging on Vancouver Island and operates its own mill in Surrey. Most of its post-and-beams are Douglas fir. Normerica also has its own plant, just north of Toronto, and usually uses Eastern white pine. In both cases, the basic system is the same—the precise amount of wood for each home is cut at the company’s mill. The house pieces are packaged and shipped, with each piece of wood numbered for correct construction at the site.
Post-and-beam construction requires slightly more wood than a standard wood-frame home. Construction time is slightly longer—about three weeks from foundation to roof and, because of the extra beam and detail work required, an additional three weeks to complete.
Although Normerica offers self-build recreational cabin packages, a post-and-beam house is not a candidate for a do-it-yourself project. You can buy design packages and there are many books on the subject, but you must have a licensed designer or architect draw the plans, and an engineer must stamp the plans to prove the strength of the beams. You also need an experienced builder.
“Most archiects know how to design a post-and-beam structure,” says Ross. “But if you’re going to hire your own builder, look for one who does this type of construction specifically. You can’t just slap up a post-and-beam house—it’s the thinking man’s construction. Post-and-beam construction is a network, more like a puzzle. If you’re out by one inch on post-and-beam, it makes a big difference. Also, the logistics are different than in normal construction. The wood has to be milled to precise specifications and there are different finishing considerations.”
Post-and-beam homes cost about 25% more than a custom house of regular construction, depending on finishing requirements. But both men agree that building a post-and-beam house is worth the extra cost.
“It’s the difference between an economy car and a luxury car,” says Ross. “The more expensive house has more advantages—in this case, openness, strength, quality of construction and design versatility. If you want better quality, better value, and permanence, a post-and-beam home is the way to go.”