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• Guide to Diagnosing & Repairing Leaks & Other Problems on Modern Kit Log Homes
• Guide to Identifying, Diagnosing & Repairing Older & Antique Log Homes
• Log caulk, spline, gasket, and coating product guide
• Log checking, cracking, shrinkage, & Leaks
• Window & Door Installation Details for Log Homes can prevent later leaks & Damage

This series of articles provides information on the inspection and diagnosis of damage to new and older log homes and includes description of log home insulation values and alternatives, and also a description of the characteristics of slab-sided log homes. 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 2008 - 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.

Guide to Log Home Inspection, Diagnosis, Repair for Owners or Buyers of Log Homes

Precision in manufacturing and assembly, combined with new sealants, gasket materials, and special wiring and other fixtures have reduced many of the complications present in traditional rough-hewn log homes. However even using the most carefully-engineered kit-type long construction methods, care and detailing during construction are important for durability and comfort in these structures.

Log homes sold as kits may have been constructed with varying levels of expert supervision. Examination by an inspector who is experienced in log construction can find some (not all) indications of the care that was taken during construction.

The author's opinions in this series of articles on the inspection, diagnosis, and repair of log homes, both antique and new, comes from having constructed, demolished, and repaired both antique log homes and new kit homes as well as from having inspected and diagnosed log home leaks, window installation, and structural concerns for owners and builders. We love log homes, but because these articles are designed to find and reduce problems in log buildings, our focus is on issues, not on the beauty, aesthetics, and comfort that can be found in log construction.

Guide to Inspection & Diagnosis of Modern Log Homes

Where to Look for Problems at Log Home Windows, Corners, & Log Splines

The windows in this new log home were installed with no spline/gasket seal between the ends of the wall logs and the window jambs. Our left photo shows our probing ruler penetrating almost 6" - the full width of the "D" profile logs (depending on where in the curved log face you're measuring) used in constructing this home - in other words, at the point where we've inserted our ruler there is absolutely no seal between the inside face of the window frame and outside of the wall jamb rough opening at the window jamb. We found this true also between the ends of the logs and the other face of the jamb rough opening.

This poor window installation detail on the solid log home combined with wide and checks in the logs near the windows (see photos below) to send water into the window assembly (see stains along our ruler where we had removed the interior sill and trim) and also into the building interior (see stains at the log/window assembly butt joint in the lower right of the photo.

The photos above show the outside log wall at the same leaky wall. The checks in the upper half of some of the logs abutting the window jamb were as much as 2.75" deep (2" at the probe point in our photo above right). These leak points combined with the absence of a window spline and gasket or caulk barrier and permitted water to enter the window jamb structure.

The "cure" for this problem was a custom-designed window head flashing and additional exterior sealing using a sealant recommended by the log manufacturer. It was also important to seal the upwards-facing log checks, as we discuss further below.

Construction at the corners of a log home, and around openings for windows and doors must be tight and properly executed to avoid drafts, leaks, and condensation problems. During arbitration of a dispute between a log home owner and the builder we found that improperly-installed windows on the home were causing window condensation and wall leaks. At the builder's own log home, built a decade before, we found that these same details led to severe structural rot in logs under leaky windows.

Windows and doors must be set, framed, and trimmed wit care to seal straight components (such as window frames) abutting rounded log surfaces (such as a log wall or log slab siding walls).

Inspect where normal log shrinkage has opened minor cracks in logs (checking cracks are typically 1/8" or more in logs) and between logs. Checking between logs in a modern kit home log wall can determine if splines were installed where they should have been to prevent leaks and drafts between the logs in a wall.

From outside the building at its corners, look into the ends of the log corner to see if you can spot the type of spline or log interlocks that were designed by the manufacturer. If your probe extends into the log groove at a building corner for a distance greater than the outside overhanging portion of the log, the gaskets were not extended to the corner as they should have been. The incomplete caulking you see in the left photo is an inept attempt to seal drafts at the building corner.

Guide to Finding & Repairing Spline Gaps & Gasket Omissions in Log Home Walls

Logs in modern kit homes are mated along their horizontal surfaces either by one or more splines that are set into grooves cut into the mating surfaces of logs as they are stacked, or the upper surface of the lower log may one or more raised ridges that set into grooves cut into the bottom surface of the log being placed on top of the lower unit.

Our photo shows a typical "D" profile log in cross-section at a building corner. The checking you see in this log end is normal and is not a structural concern. But notice how the left-hand large check just below the middle of the log slopes down to the log interior ? This opening will collect water and can lead to long term log rot or frost damage.

Log kit specifications usually call for either caulk applied atop the raised spline, or as in the case of the log we show here, along the two raised splines. Other log companies call for a special gasket to be placed either atop the splines or along side them to assure that these joints will be weather tight.

Splines, gaskets, or caulk are also specified between the ends of abutting logs. As you can see from our ruler in this photo, there was no obstruction between the indoor and outside surface of these butting logs in this leaky log home.

Having worked on a log home construction crew we can testify that in the rush and excitement of keeping up with the crew setting logs around the building, the individual or crew whose job it is to place the caulk or gasket may fall behind. It's easy to place and fasten down a log without noticing that the spline or gasket was omitted.

Probing horizontally into the openings cut for log splines you should be able to feel the presence of a gasket or caulk along-side or atop the spline openings.

From inside a building if you see daylight between logs of an exterior wall, or if you feel drafts during windy weather, or if you can probe all the way through the wall such as in our photo above, splines and/or gaskets may have been omitted.

Omission of splines or gaskets specified by the log manufacturer will lead to infiltration losses, drafts, possibly water leaks from wind-blown rain, and higher heating bills.

We advise against simply using generic caulks in these locations. Luckily, and probably because this is a common error, there are special products that can be used to remedy leaks in log walls. If inspection or if cold, windy weather reveals air infiltration leaks, call your inspector or log manufacturer for suggestions for special log chinking, caulks, or other log home crack or leak sealants.

Guide to Shrinkage In Log Home Walls

Log homes will shrink considerably in wall height as the logs dry during the first one or two years after construction. This is so even in factory cut "dry" logs which may have absorbed moisture in transit or on site, and it is even more true if the logs used in construction were "air dried" or were used while still "green".

The more moisture that was present in logs at the time of construction of a log home, the greater the amount of shrinkage that will occur in overall wall height, and the larger and more extensive will be the checking cracks that occur in log walls.

Log Checking or Splitting - Are Log or Beam Splits A Structural Concern?

Log checking, long horizontal splits in the log surfaces, will appear on both inside and outside surfaces of log walls and may vary considerably in width (hairline to 1/2") and length (a few inches to several feet). (Photo courtesy Arlene Puentes.)

Checks in logs (or other large timbers) are rarely a structural concern, but they may become a leak or rot problem. Checks are only a cosmetic concern unless they are taking in water and therefore risking leaks into the building interior or causing rot or inviting insect damage, as we discuss below

Problems Caused by Checking and Splits in Log Walls

Checks and splits in the upper radius of log walls on the wall exterior are of more concern than checks and splits in the lower half of these walls.

Checks even in the lower radius of log walls - that is just below the center or outward-most face of the curved log face may also be a problem if they occur in a position and shape to send water running down the log wall into the log interior. Rain or melting snow sending water into these checks can cause these problems:

• Rot damage or insect damage
• Leaks into the building interior, especially where the checks lead water to a poorly-sealed window or door frame.

Checks in the lower radius of the curved outer face of a log wall and checks in weather-protected location are unlikely to cause damage and are only cosmetic.

Interior Condensation and Moisture During Log Home Curing

Considerable moisture may be released during the first year or two after construction of a log home, after the home is totally enclosed and central heating / air conditioning have been installed.

Log moisture content is easy to measure using any of several types of moisture meter. Log moisture measurements can help determine whether the condensation seen in a log home is coming from the logs as they cure, from leaks, or from some other moisture source.

Log Wall Height Changes During Log Curing

Log walls can shrink up to several inches in overall height during curing, depending on how much moisture was in the logs when the home was constructed. There may also be some seasonal changes in the height of a log wall as ambient moisture varies and as heating or air conditioning are used in the home.

Modern log homes use construction details and log fasteners designed to permit this log shrinkage movement without damage to other rigid building components like windows, doors, plumbing, electrical wiring, and fixtures.

Quick Guide to Log Sealants & Coatings

Some of the really unfortunate disasters we've seen on log home exteriors were caused by use of a log coating or sealant which was not recommended by the log manufacturer. Use of the wrong sealant can lead to peeling and ugly surfaces that can be very costly to correct.

Here are some Log Home special sealants and caulking or chinking products. But before applying anything to the logs on your home, inside or out, find out what products your log manufacturer recommends.

• Geocel Caulk or other GE^TM caulking products specifically designed for log buildings
• Compriband^TM, an impenetrable sealant made by Secoa Corporation, Warminster PA
• Log Home Foam^TM, Norton Sealant Operations, Granville, NY
• PR-5636^TM, poltyurethane sealant, Products Rersearch & Chemical Corp., Glendale CA
• Traditional mortar log chinking (we do not recommend this approach as it falls out, leaks, requires frequent repair)
• Lifeline^TM Natural Wood Finish (acrylic polymer) from Perma-Chink Corp.
• Preservative stains, pigmented, penetrating type: we've used these with success on slab log siding on log homes; a good practice for maximum durability and insect resistance of slab log siding is to seal all surfaces of the log siding before it is installed.

Producers of other products for the repair or protection of log homes are welcome to submit product data for inclusion; there is no fee; our website has no financial relationship with any of the products or materials discussed here.

Technical Reviewers & References

Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.

• Daniel Friedman - principal author/editor of the InspectAPedia^® Website
• Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
• Critique, contributions wanted: Contact Us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.

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
    Where to Look for Problems
    Spline Gaps & Gasket Omissions
    Guide to Shrinkage In Log Home Walls
    Log Checking or Splitting
    Log Home Condensation &Moisture
    Log Wall Height Changes
    Log Home Sealants, Caulks, & Coatings
    Antique & Old Log Cabins
    Vertical Log Cabin Walls
    Slab Log Cabin Siding

Comparing the Insulation Value of a Solid Log Home to a Conventionally Framed Home

A 6-inch fiberglass frame wall has an "R" value of about R-19 while a 6" log solid wood wall has an "R" value of about 1 per inch or about R-6 in insulating value. When a solid log wall is built using logs rounded on one or both exposed sides, the nominal log diameter does not give an accurate estimate of the wall's insulating value. That is because portions of the wall are constructed at a thickness less than the full log's diameter. The average wall thickness should be used to calculate the "R" value of a solid log wall when rounded logs are used.

Thermal Mass 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.

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.

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.

Technical Reviewers & References

Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.

• Daniel Friedman - principal author/editor of the InspectAPedia.com ^TM Website
• 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.
• "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
• Critique, contributions wanted: Contact Us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.

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