Is That Post and Beam or Log?
A Comparison of Post and Beam and Log Homes
By Joi Singleton Tannert, ASID
When it comes to Frequently Asked Questions, I think the one we hear most often would have to be, "Post and beam, ah, is that like a log home?" And a most likely answer could be "yes…and no". To the interior viewer, a post and beam and a log home both have exposed wood frames and often, wooden walls and ceilings. They rely on the large skeleton to support the load of the home. But actually, that is pretty much where the similarities end. They seem to have more differences.
The exterior of a log home is unmistakable. It is the very style of the home, and sets it apart from any other type of home. Post and beam, on the other hand, is not a style, but a structure type. You cannot usually detect it until you enter the home. The exterior can look like any other style of home…saltbox, farmhouse, Cape Cod, contemporary, Country French, Craftsman, lodge, etc. It easily blends into most neighborhoods and meets architectural review covenants without a problem. Since the walls are not dictated by the product structure, post and beam walls and ceilings do not have to be wood, but can be drywall. This creates more flexibility for interior design styles to be more varied, as well.
Post and beam homes are typically more energy efficient than log structures. Since the structural support is exposed on the inside, the walls and ceiling are built with a continuous wrap of rigid insulation attached to the outside of the skeleton. All gaps are sealed in the installation process. This results in a more efficient use of the R-value in the insulation. All walls are a uniform thickness. Most traditional log homes depend on the thickness of the logs to be the insulator. With round logs, obviously the thickness varies from the center to the edge of the log. Some add small amounts of insulation, along with caulks and sealers, to the area where the logs join each other. There usually are no multiple layers to trap air or block water vapors from entering, so sealing between the logs is a must. You generally need to increase the size of the logs to increase insulation value. This creates a thicker wall and results in a visual proportion change to the rooms inside. Some log companies offer insulated walls of standard 2x4 construction that incorporate an exterior of half logs in order to reduce air infiltration and increase R-value in the walls.
One major difference I have found is the way we use the wood and the structural character of wood itself. A wood pole or post, by nature, will shrink and expand in its width or diameter, depending on the moisture content in it, which is, in turn, affected by the humidity around it. The temperatures and humidity inside a home are never totally constant. In post and beam, the length of the wood is used vertically as our main support, joining lengthwise horizontal members by mortise and tenon joinery. The joints are then locked together by wooden pegs. Attached walls are non-loadbearing. A post which shrinks widthwise may show a slight visual gap where the beams join on each side, but results in no structural problems with which to deal. Log homes, on the other hand, use the wood stacked on its side. The amount of shrinkage in the width of one log is compounded by the number of logs stacked in the wall's height. Log home manufacturers and builders have to plan ahead for an estimated amount of shrinkage, usually 3", and build in adjustments to doorways, windows, stairs, plumbing runs, etc. After the home has had time to acclimate and settle, the builder sometimes has to come back and make the necessary adjustments.
I have been told more than once by potential buyers, "At first, I was interested in a log home, but didn't want the maintenance issues." This prompted me to find out what they meant. My research yielded a lot of information about the exterior of the home. Apparently, the log movement affects the exterior even more than the interior, since there is more fluctuation in the temperatures and humidity outside as the days and seasons change. The area between the logs is a critical area. Sealant, caulking, and chinking have various potential hazards. Blisters in chinking and caulking can be a problem. Logs have "pitch pockets" of sap which causes a gas when heated that can lead to cracks and blisters. Also, as large-timber wood shrinks, cracks called "checks" appear lengthwise in the wood. In post and beam, checks cause no problem because they are inside and only visual, so they just add character. When they occur on logs on the outside, and especially on the top half of the log, they open an area that allows moisture and insects to enter the log. Logs are recommended to be stripped, re-stained, and new preservative every 3-5 years. Chinking also needs periodic patch or replacement. Post and beam homes use standard wood siding which is vertical, shingled, or clapboards, beveled to shed water. Some are even brick, stone, stucco, cementous, or combinations of those with wood. Wood sidings are usually painted or opaque-stained, and often back-primed to minimize exposure and warpage. Products are available to coat the siding and trim which carry a 12-15 year warranty.
Perhaps, since many of these issues fall on the homeowner, it contributes to a lower cost initially for the log product. After all, buying one log provides the interior, the exterior, and the insulation at the same time. Post and beam walls require tongue and groove planks (or drywall and plywood backer) for the interior surface, insulation, exterior strapping or plywood support for the siding, and a siding product. Each of these must be installed, so the labor factors in, as well.
I've found that most of our buyers plan to keep their homes for generations to come. I saw a saying once, that went "When you buy quality, you only cry once." When trying to decide what's best for you, it really comes down to what fits into your dream…
JST
Joi S. Tannert and her husband, Ron, were Independent Representatives for Timberpeg Post and Beam Homes in the Triangle for 15 years. Their building company is Natural Homes located at 8208 Whispering Glen Ln, Raleigh, NC 27614. Joi also is an interior designer and has Art of Design at the same location. They can be reached at 919-870-1170, or jstasid@aol.com. www.naturalhomesdesignbuild.com