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Home Buyers/Owners Guide to the Insulating Value (R-Value) & Heating Comfort of Log Homes InspectAPedia®  -

• Log home insulating and R-value properties
• Comparison of the insulating and thermal properties of solid log homes with other structures

Here we discuss the insulating and heating properties of log homes, comparing solid log structures, slab-sided log homes, and conventionally framed homes.

This series of articles provides information on the inspection and diagnosis of damage to new and older log homes and includes description of log house and log siding insulation values and alternatives, and also a description of the characteristics of slab-sided log homes as well as all other types of log home construction. We include illustrations of log structures from several very different areas and climates in both the United States and Norway. Our page top photo shows a modern kit log home constructed in New York State.

For modern kit and factory-sourced log structures we include details of common construction and building defects that cause water and air leaks and ultimately rot damage and we point to key problem areas that need to be inspected carefully when buying or maintaining a log home.

© Copyright 2009 - 1991 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

A Comparison of the Insulation Value of a Solid Log Home to a Conventionally Framed Home

Thermal Mass & R-Values of Solid Log Homes Compared with Insulated Wall Wood Structures

While the "R" value of a solid log home is almost certainly less than that of a modern conventionally-framed stud wall home insulated with fiberglass or other products, the wall "R" values alone do not accurately describe the comfort level of a log home. Provided that the log construction has been well-built without drafts or leaks, the thermal mass of solid log walls is considerable.

Average R-value or Insulating Value of a Solid Log Wall

Solid wood has an R-value of about R-1 per inch of thickness. A round log wall using 8" diameter walls is not, however 8" in uniform thickness; that wall thickness is reached only across the center of each log. The scalloped wall surfaces will certainly be less than 8" (R-8) in thickness where log faces meet one another. Compute the average wall thickness of solid wood to arrive at a reasonable R-value estimate for a solid log wall. Typically for an 8" log the average log wall thickness is around 6 to 6.5".

Consider Thermal Mass in Addition to R-Value of a Log Home

Log home enthusiasts argue that in measuring comfort one should not only consider the "R" value of the building walls and roof but also the thermal mass of the building. High thermal mass (provided by the mass of solid logs in a log home) means that the building will be slow to change in temperature.

We agree that overcoming drafts and un-wanted air leaks is the first priority for making a building comfortable and for reducing heating or cooling costs in cold climates. INSULATION R-Values & Properties provides detailed estimates of the insulating values and properties of various insulating materials.

A large thermal mass in any building tends to make temperature changes occur more slowly than in structures lacking that feature. As a result, occupants of solid log homes often assert that they find their building very comfortable in both heating and cooling seasons.

Log Slab Sided Log Home Insulation R-Values

Slab-log sided homes such as the one shown here and discussed in detail at Slab Log Cabin Siding are generally built over conventional wood-frame walls that allow conventional wall insulation.

This cabin was renovated using 2x6 wall studs to permit extra in-wall insulation as well as the application of solid foam insulation on its exterior walls. The walls of this building were framed to about R-20. Very important as well, the builder did a great job assuring that the home would be draft free.

After a horribly incompetent installation of an in-floor radiant heat system (by the same builder who did so well on framing and insulation) we had to abandon the heating system for this Minnesota cabin. Luckily the cabin is so tight and well insulated that we discovered that we could heat it for at least three seasons using just a few portable electric baseboard heaters. See RADIANT HEAT Floor Mistakes to Avoid.

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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

LOG HOME GUIDE
    Types of Log Houses - Log Choices
    Antique & Old Log Cabins
    Cracks, Checking or Splitting Beams & Log Homes
    Condensation &Moisture in Log Homes
    Insulation Values of Log Home Walls
    Leak Diagnosis & Cure for Log Houses
    Log Wall Height Changes
    R-Values of Log Homes
    Sealants, Caulks, & Coatings for Log Homes
    Shrinkage In Log Home Walls
    Slab Log Cabin Siding
    Spline & Gasket Designs for Log Buildings
    Spline Gaps & Gasket Omissions
    Vertical Log Walls on Cabins & Home

• Thanks to Arlene Puentes for the photograph of a checked log in a log home exterior. Arlene Puentes, a licensed home inspector, educator, and building failures researcher in Kingston, NY. Photographs © Arlene Puentes 2006 All Rights Reserved. Text © Daniel Friedman Arlene Puentes 2008 All Rights Reserved.
• "The Logless Log Home," Jim Robbins, New York Times, 01/22/2009 Home section, p. D1 & D6.
• "Shop Talk," Martin Mintz, AIA, Builder Magazine, April 1986, detailed solutions for log shrinkage movement by using a "T" jamb at windows and doors. A January 1986 Builder Magazine article shows window installation details in 8" thick log walls.
• "Caulking, Chinking, Insulators, Sealants - which System works Best," Log Home and Alternative Housing Builder, Nov-Dec 1983.
• Lincoln Log Homes Marketing, Inc., 6000 Lumber Lane, Kannapolis NC 28081 704-932-6151
• Insulating Characteristics of log homes were neatly summarized by Roger Rawlings in "Log Homes in a New Light," Rodale's New Shelter, April 1983, p. 28
• Merrimac Log Homes, Henniker, NH, sells log home products, milled log home kits, log siding, and log home plans and log home construction accessories. 866-637-7462 or logs@mlhnh.com - merrimacloghomes.com
• PermaChink Systems, Knoxville TN 800-548-1231 provides a range of log chinking products, coatings, and sealants for log and other wood buildings.
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