Stacked log construction is a building construction technique with which structures are built by stacking one wooden log over another. These logs are carefully interlocked by their end notches ensuring a tight arrangement capable of weathering the natural seasoning and the settling process.
Earlier, Stacked log construction technique was prevalent for the construction of commercial buildings, houses, churches, schools, etc., but today this technique is used in elaborate houses with varied style and options.
The types, features and the benefits of stacked log construction are explained in this article.
Features of Stacked Log Construction
Stacked log construction mostly uses wooden logs that are locally available. Ideal wooden logs are obtained from the coniferous trees as they provide long solid sections. The wood species mainly used are:
- Yellow Pine
- White and Yellow Pine
- Alpine fir.
The logs can have a diameter ranging from 8 inches to 10 inches. The length is determined by the type of log used. The logs used for the construction can be either:
- Handcrafted Logs
- Milled Logs
1. Handcrafted Logs
These logs are made by cutting wood from the forest and the barks are removed by hand using a draw-knife or by water peeling method. The logs can be either used green or can be air-dried. Also, these logs do not have a uniform shape and size. So during construction, logs are either fit together or stacked one over the other.
2. Milled Logs
These wooden logs possess uniform shape and size, which hence gain a good profile. These are available as coped logs, square logs, full round logs and shaped logs.
The preparation of milled logs include:
- Cutting logs from the forest
- Transport to mill
- Logs are debarked
- Logs are shaped by a sawmill, planer or lathe
- Cut to shape
- Logs are let green or air-dried or kiln-dried
Types of Stacked Log Construction
As explained before, the stacked log construction technique involves stacking logs one over the other to generate walls. At the perpendicular corners, they are interlocked. This construction can be performed in different styles. They are:
- Chinked style
- Chink-less or Scandinavian Full-Scribe Method
- Dovetail Style
- Full–Scribed or Full Cope style
1. Chinked Style
In chinked style construction, the logs are placed one over the other without going through any cutting. The spaces and gaps formed are filled by the means of synthetic material. ''Chinking'' is the filling used to fill the gaps between the horizontal rows of logs.
The advantages of chinking are that no cutting of the logs needs to be done and electrical wires can be hidden behind the chinking. Also, chinking is cheaper as there is a substantial saving in labor costs.
In this method milled or scribed logs are stacked one over the other to generate walls. The corners are notched and they are fit together to minimize the chinking process.
3. Dovetail Style
In this construction style, the special compound angles are formed by the corner joints of the logs and hence interlocked. This compound angle style is named as a dovetail. The dovetail joinery is made by a hand-hewn timber or by the means of a log flattened on two sides.
The dovetail style requires chinking after the assembly. The compound corner joints and surface texture help preserve the historical log crafting artistry. Because chinking is pliable, it yields greater flexibility with seasonal and climatic changes.
4. Full–Scribed or Full Cope style
A full scribed technique involves cutting the underside of the log in order to match with the exact profile of the log underneath. The construction process is slow and expensive but it ensures a better quality structure than chinking.
Sealants are necessary for scribed logs. These logs are sealed by expandable foam which is injected into the scribes. Some of the methods of scribing includes:
- Round Notch
- Saddle Notch
- Norwegian Notch
- Scandinavian Full Cope.
Benefits of Stacked Log Construction
The main advantages of stack log construction are:
- Stacked log constructed structures are aesthetically pleasing.
- This construction technique reflects and promotes heritage value.
- In areas where other construction technologies are not present, this method is a better choice.
Some of the drawbacks of stacked log construction are:
- It demands huge coniferous forest trees thus promoting deforestation.
- The cost of ferrying the wooden logs are high.
- The logs tend to shrink and compress with time which reduces their radial dimension. The shell, hence, reflects breaches which reduce the energy efficiency of the structure.
- Construction and Maintenance cost is high.
- Poor Insulation Properties