There are a number of factors that determine the quality and strength of a log. The Log Home Council, an organization of log home manufacturers, developed a log grading system to determine the structural integrity of a log. The system addressed defects in logs that affect its strength. Those defects include, among other factors, the slope of the grain, the size and density of knots, holes, splits and checks and decay. There are four grading levels of logs depending on strength requirement –
beam, header, wall and utility. The grading sets a maximum number of defects for each classification.
The levels are:
Beam – Supports a structural load
Header – Above a window or a door
Wall – stacked wall
Utility – used for sheds and barns
The defect categories among others are:
Slope – The angle of the slope of the grain, i.e. the change of angle of the grain from parallel between the edges of the log. The larger the angle, the weaker the log.
Knots – There are numerous knot classifications. Defect rating is driven by knot circumference and concentration. The bigger the number, the lower the strength.
Checks and splits – Wood naturally develops cracks in the growth or drying process.
Decay – the wood rot caused by fungi.
Warp – a distortion of the log shape
Log standard enforcement is up to the local authority. It is not commonly enforced. Nonetheless, you as home owner should insist on grading. Graded logs are more expensive than ungraded but as they say, ‘you get what you pay for.’ The end result is more than worth it. Nonetheless, I would confirm that your manufacturer does grade the logs. They will stamp the logs or provide a certificate of grading. The Log Home Council does audit the manufacturer’s classifications. Personally, I would make it a condition in my sales contract. If you don’t ask, you will never know with absolute surety. If they balk, I wouldn’t trust them anyway.