Log Home Construction Techniques
We in the Highlands of Scotland are fortunate that there is an abundance of softwood conifer forests ably managed by the Forestry Commission and sawmills. From here, we can purchase a selection of logs about 5m long and 250mm diameter to build the dwelling. It is preferable to purchase seasoned logs, but the bark must be completely removed before starting construction as the bark is home to many types of wood fungus and, beasties such as Horntail - Urocerus gigas.
Concrete foundations may not be everybody’s favorite means of holding up your building, but believe me I have seen some log cabins just set on blocks of hardwood and they soon begin to sag or get blown over. So again think it through, there will be the high CO2 footprint due to the concrete, but this will be offset by the many extra years the sturdier and safer dwelling will remain standing on a concrete foundation.
Walls and Floors
A small support wall is built from concrete blocks or stone on top of the foundations. The log sills which are hewn flat at the bottom and lie along the length of the outer wall are fitted and held down by anchor bolts. The ends of the sills protrude beyond each end of the walls where they are attached to each other using a nailed mortise and tenon joint. Internal joists hewn flat on top and bottom should also be fitted to support internal walls and the flooring. These joists themselves should be supported by up-stands made from log offcuts nailed together and set on top of the concrete founds. Logs used for the walls are joined together using notched joints at the ends and pinned to their neighbor using wooden pegs.
Once all the door and window apertures have been cut in the walls the roof can be installed. Depending on available lifting plant the gable ends and rafters can be assembled on the ground then fitted to the wall top sills with notched joints.
Roofing boards or sarking (again supplied rough-cut from the sawmill) are nailed to the rafters then the wood roof shingles fitted over the boards using the same method as fitting roof slates.
Doors and windows are then fitted; all the inner room dividing walls and outside walls are then given a few liberal coats of linseed oil, leaving plenty of time between coats for them to dry thoroughly.
Any gaps between the logs on the outside walls, doors and window jambs, wooden roof boards can then be caulked with oakum, a mixture of wool and wood tar. This prevents water ingress and drafts but remember to coat the logs with linseed oil first, otherwise the oakum caulking will stain the wood.