The 21st Century learning experiences gained as the community, school and businesses design, plan and build a 32 foot long Town Lattice Truss covered bridge for the Village of South Wayne, Wisconsin.
Wednesday, August 2, 2017
Log Cabin Building 101 Part #1
Well it is hard for me to believe that it has been a month since I last posted about Lynn's log cabin project. So I will try to bring those interested up to speed and the process that goes into a project like this.
In the last cabin post of July 4th you saw the trailer load of logs and pictures of the 24 by 18 cabin they came from. Step one was to lay the logs out on stickers to see just what we had. One of the things we had were the top wall logs that were noted for the loft floor joists.
Next each log was numbered. There were 65 logs. All were hewed to about 6 inches in thickness. However they varied in length from 2 to 24 feet and height from 7 to 13 inches. I placed the recorded sizes for each log on a spreadsheet. Then I could sort them out by length (most important) and height (widest logs would be used for the bottom logs of the cabin).
It is noteworthy to consider the numerous square nails that were used in the first construction of this cabin 100 years ago as they will be a problem when recutting the logs for rebuilding.
After two or three days of sketching and drawing a full set of prints were made using Auto CADD. For that I used an average log height of 9 inches. Working from the log list I was able to select full length logs and decide on window sizes and placement to make use of the shorter logs. Then it was time to make a scale model using foam core board to get a feel for the proportions and how the porch roof would look. This also helped Lynn see just how the final cabin would look. Everything was good to go.
One more thing that plays into the construction is the size of the chinking joint. This is determined by several factors one of them by the angle of the half dovetail. I was going for from 2 to 2 - 1/2 inch spaces and like around a 17 degree angle for looks and water shedding. To put my mind to ease, since there were no extra logs I decided to use some of the 2 foot pieces and test out my joint design. I was pleasantly surprised. So I was time to get building!
I selected my location and found the highest corner point this would be zero. The other three corners would be blocked up accordingly to bring them to level. The plans were drawn with 2" overhangs on the corner joints. Making the log lengths needed 21' - 6" and 16' - 6". I want the cabin walls to be sitting on a 2x6 treated plate for moisture protection from the concrete pad the cabin will go on. Lucky me 2x6's only come 16' long so I would have to scab on a piece to get the 21' - 2" length I needed. Anyway I placed the boards on edge to get level and then laid them down and put in some more blocking the support them.
OK so now with a nice level, supported 2x6 treated plate. I made the door frame out of 4x6 material, placed and braced it plumb where it would go. This way I will have a surface to anchor the ends of the logs that do not sit on a wall for support.
The question always is, "How do you move logs this heavy by yourself?". The answer is. "I let the wheels and ramps do the work." These 24 foot white oak logs weigh in at between 300 and 400 pounds each! But with a roller under the log it moves easily out of the pile.
To get the logs from the pile to the cabin wall I have built a little contraption that does the job. With the log secured at its balance point all the weight is on the wheels and a 400 pound log "merrily rolls along"!
For the shorter logs I just strap on a set of wheels at the midpoint and roll these to the cabin wall.
Ahhh.. the feeling I get when a plan comes together and the results are what you wanted. The first cuts have been made and the clearance on the long walls is just a bit over 6" for a filler log piece.
Ramps are used to get logs higher up on the walls of the cabin. They will get pretty long for the top rounds of logs!
Windows and doors always cause a problem in the construction because there is nothing to support the log by the door or window when doing lay out. To solve this problem I have built a nifty little set of adjustable vee blocks that can be used. Here you can see them at work. When the log has been cut and fitted screws are ran through the door/window frame to secure it in place and the vee block removed.
So here we are. After a week of cutting and fitting. Keeping in mind to make the corners come out the same height. Keeping the walls plumb and the chinking gap around 2 to 3 inches. Next will come the window framing. After that the loft and then the roof. Will report the progress as I go in Part 2 of Cabin Building 101.