We perform home inspections in many different types of homes and, over the years, we have seen various new materials used for homes but, despite this, log homes have always remained a popular option. As either pre-cut in a factory or site-built, many manufacturers allow for a customized design and there are many factors that you should be considering if you want to aim for energy efficiency.
R-Value of Wood – Firstly, wood will help to provide insulation and its given ‘R-value’ shows its thermal resistance. If the R-value is high, it will be more thermal resistant than a lower number. For softwoods, the scale starts at 1.41 per inch whilst most hardwoods achieve around 0.71. For example, a thick log wall of 6 inches would see a clear wall value of around 8. By definition, clear wall means no windows or doors as these factors will affect thermal resistance.
When it comes to insulation, wood is normally a far inferior solution when compared with a more traditional wood stud wall – 31 D2 inches insulation, wallboard, sheathing; this will bring a total of R-14. Therefore, many log walls struggle to meet the standards for building codes. However, this can be changed if the log building can interact with its surroundings through the changing climate. Because the logs can store heat, the walls can be better in some climates than in others because they have a large mass. With this in mind, logs can store excess heat during the day and release it gradually through the night just like thermal batteries. When this process occurs, its R-value increases by 0.1 per inch when the weather is right. In a perfect world, the conditions would be sunny during the day with a a large swing in temperature at night. In Earth’s temperature zones, this normally occurs between the 15th and 40th parallels.