ButtSpline® System


We use the naturally occurring shrinkage of the log to our advantage with our ButtSpline® technology to make your log home air tight.


  1. Two holes are drilled in the end of each log to create a figure-eight shape as they butt together in a wall assembly.
  2. A custom made ButtSpline® clamp is inserted into pre-drilled holes and pressure is applied to draw the joint together.
  3. An asphalt-impregnated figure eight foam pad is installed at the bottom of the holes.
  4. A two-piece polypropylene  assembly is wrapped with asphalt foam tape and then dropped into the holes.
  5. Two 10-inch common spikes are driven into the two-piece assembly, wedging it apart, tightening the joint.
  6. Another asphalt-impregnated figure eight foam pad is installed on top of the assembly.
  7. The clamp is removed.
buttspline assembly
buttspline assembly installation


The natural shrinkage in the width of the log (green arrows).

The log squeezes on the radius of the ButtSpline®. At the same time (shown with blue arrows) the log shrinks lengthwise, pulling on the ButtSpline® causing the joint to tighten over time.

*Systems shown and used by True North Log Homes Inc. are protected by patents and patents pending – U.S.A. and Canada.