To the untrained eye a log building is a log building, but after closer examination the differences are not only obvious, but immediately identifiable. I am only including methods that are “scratch built” not kit homes with machined logs. In this month’s entry I will briefly explain the 3 main methods of log building beginning with the simplest.
BUTT AND PASS
Compared to the 2 more traditional methods the butt and pass method seems to be the newcomer in the mix. There is very little information out there on the subject, so I contacted the good folks at the Onalaska Log Building School www.onalaskalogbuildingschool.com to help me offer our readers some accurate information. I am not sure why, but I have noticed more of these structures in the western parts of the US.
In this method there is no scribing or even saddle notching. As the name implies one log butts into the other log that passes through. The diameter of both the logs at the butt and pass joint should be very close to the same diameter to assure a nice look. So what holds the logs together you ask? Lengths of ½” rebar are driven in approx every 6’ to affix each row to the logs below. Supposedly these structures do not settle like other log buildings do, so one does not need to build in the allowances for settling around windows, doors and any support posts. I still do not understand how a building that weighs that much does not settle, but that is the claim. By not having to scribe the logs to one another considerable time will be saved at this stage of the construction process, but let us not forget that there is extensive chinking involved compared to a full scribe method that , if done correctly, requires little if any chinking. I have included photos of all 3methods, so you can decide what look you prefer and how much time you would like to spend on your project.
Once you are able to identify the differences in construction you will no doubt notice a good number of saddle notched structures. They go up fairly quickly as the only scribed portion is where the logs overlap at the corners. The saddle notch method resembles the more traditional Scandinavian method in that the logs at the corners all overlap one another. This is essentially what holds the building together. Where the log run is broken for window and door openings a hole is bored (approx. 1 ½”dia.) and a peg is inserted through the upper log into the log below to keep the logs aligned. Make sure that the peg is not too snug as this can prevent the structure from settling if it binds. As with the butt and pass method there will still be gaps between the logs that will need to be chinked and, depending on the fit, at the saddle notches as well. There are several commercially available chinking/caulking products that the log builder can choose from that are specifically developed for log buildings. We will dedicate a future blog to chinking and exterior finishes.
I am not aware of any schools that teach this method, but there are many books that explain it well.
This method is often referred to as Scandinavian Full Scribe and more recently the term “under-scribe” is used. This refers to the scribing process that uses slightly different scribe settings to assure that the logs, when fully settled, are tight at the laterals, saddles and flyways. After the 1st log is placed each subsequent log is scribed to the log below it. What this means is that any bump or natural irregularity in the lower log will have a corresponding cut in the log above it so that they will “nest” together. This scribing technique is best achieved with a double level scriber fitted with an indelible pencil. A chain saw is then used to do most of the work which then requires some hand work with a chisel and/or handlebar gouge / scorp. When done properly it will result in a tight fitting joint that does not require chinking. Often times it is not even possible to slip a piece of paper between the logs. As mentioned earlier one must make allowances in door and window openings as well as any support posts for settling of the logs.
This method of log building does require more skill, tools and time. I would highly recommend that one get some hands on training to learn these skills. A good school here in the Midwest is The Great Lakes School of Log Building in Isabella, MN. http://www.schooloflogbuilding.com/ I have attended the 10 day course and can attest to its value. At the very least study a good book on the subject. Another good source of information is The International Log Builders Association http://www.logassociation.org/