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STRUCTURAL INSPECTIONS & DEFECTS
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DISASTER BUILDING INSPECTION & REPAIR
EARTHQUAKE DAMAGED FOUNDATIONS
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FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
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LOG HOME GUIDE
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MODULAR HOME CONSTRUCTION
MOISTURE CONTROL in BUILDINGS
PORCH CONSTRUCTION & SCREENING
PRE-CUT & KIT HOMES
RETAINING WALL DESIGNS, TYPES, DAMAGE
ROT, FUNGUS, INSECT DAMAGE
SINKHOLES, WARNING SIGNS
STAIRS, RAILINGS, LANDINGS, RAMPS
STRAW BALE CONSTRUCTION
STRESS SKIN INSULATED PANELS
STRUCTURAL WOOD ASSESSMENT
TIMBER FRAMING, ROT
TRUSSES, Floor & Roof
WATER ENTRY in BUILDINGS
This article defines, illustrates, and explains the cause and significance of splits or "checking" in logs and beams including in log home structures. Checking or splits in solid logs used to construct both antique and modern log houses worry homeowners even though usually they do not present a structural problem. But checks in structural wood beams as well as checks and splits in logs used to construct log homes can result in water or air leaks into the building. Also see ROT, TIMBER FRAME for a discussion of the cause and prevention of log checking during log or timber dryout, and for a case study of rot in timber frame construction. Our page top photo shows the author's precision probing device exploring checking (also called splitting or cracking) of a structural wood beam in a pre-1900 home that had been moved to a new concrete block foundation. As solid wood beams and logs cure, shrinkage produces not only checking (large cracks that are normal and are not necessarily a problem) but also an actual reduction in log or beam diameter.
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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.
Usually the crack in the wood beam or solid log radiates from the outer surface of the log towards the log center; it is not common for a log or beam split or crack (or checking) caused by the drying process to pass beyond the center of a log or beam. However more severe splits and cracks can occur in a wood structural member, even passing through its full diameter, due to structural loading or 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 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.
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
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:
So as our photo (above left) shows, even a structurally harmless shrinkage crack or check in a log wall can lead to an interior leak if the window was not properly constructed. This particular log check reached to the center of the log and bypassed the caulk that the builder had placed around the window frame on the log wall exterior.
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.
Tips for Avoiding Leaks at Splits & Checks in Log House Walls
Frequently Asked Questions (FAQs) about checking or cracks & gaps in logs used in log homes
Questions & answers or comments about splits or cracks in wood beams or in log home log walls.
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
Log Home Design, Inspection, Maintenance, Repair References & Product Sources