Log houses originated in Europe where they were hastily erected as hunting cabins. Stacked log homes today are elaborate structures worth several hundred thousand dollars in some cases. Coniferous trees are ideal for constructing stacked log houses are the timber can be obtained in long solid sections. Pine, cedar and fir are the preferred species for stacked log construction. A majority of the log homes are preconstructed in log yards and then brought to site and assembled in a matter of days.
As the name suggests, logs houses are made by stacking logs one over the other to generate walls that are interlocked at perpendicular corners. There are three predominant styles of log construction (www.customlog.com):
- Chinked style
- Dove Tail Style
- Full –Scribed or Full Cope style
In the chinked style, the logs are placed one over the other without any cutting. The resulting spaces and gaps are then caulked and chinked using synthetic materials that are essentially polymerized rubber with adhesive. The advantages of chinking are that no previous 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.
Dove Tail Style
A dove tail detail for log houses
In this style, the Dovetail is so named for its compound angles that naturally interlock the corner joints. Dovetail joinery is generally utilized with hand-hewn timber or logs flattened on two sides. This type of construction requires chinking after reassembly. Dovetail wall surfaces accommodate framing of interior walls and hanging cabinetry with greater ease. Flattened log surfaces make interior decorating easier and more convenient.
The compound corner joints and surface texture help preserve historical log crafting artistry. Because chinking is pliable, it yields greater flexibility with seasonal and climatic changes.
Full –Scribed or Full Cope style
Scribing involves cutting the underside of the log so that it matches the exact profile of the log underneath. The construction process is slow and expensive but it ensures a better quality structure than chinking. The scribed logs also require sealants and should be sealed using expandable foam that must be injected into the scribes. Some of the methods of scribing include the Round Notch, the Saddle Notch, The Norwegian Notch and the Scandinavian Full Cope.
The advantages of using log homes are:
· Log homes are aesthetically very pleasant
· They have tremendous heritage value
· They are ideal for areas where other building technologies are unavailable.
The disadvantages of stacked log construction are:
· Log homes tend to impose strenuous demands on coniferous forests and should therefore be used only where the appropriate wood is abundant.
· Transportation costs for ferrying the logs are high
· Logs tend to settle due to shrinkage and compression. There is a loss of radial dimension in the logs as they tend to shrink and compress with the passage of time. This settling leads to noticeable breaches in the shell and reduces the energy efficiency of the structure. Additionally, skilled carpenters are needed to predict the shrinkage and address the problem at the construction phase itself (www.loghomelinks.com).
· Log structures are expensive to build and maintain.
· Log structures have a poor thermal insulation properties and serious breaches through joinery cause air infiltration and heat loss.
· Log structures use the most wood of all the construction technologies available for a particular structure.
· They are prone to mould and mildew.
The codes do not really address the issue of stacked log construction. However, they are readily accepted in areas that have a history of building and inhabiting log structures. It can be successfully argued that log structures can meet structural codes by virtue of their inherent strength. The R-values of log walls are not code compliant (Allen & Thallon, 2001). This problem is doubled by the noticeable air infiltration that takes place through the cracks.
Stacked log structures though pleasant in appearance, are clearly detrimental to the long-term future of the environment. The energy consumed through the entire life cycle of the log structure is enormous and unjustifiable though logical reasoning.