Leaks at the window of a log home Repair Air & Water Leaks in Log Home
Walls, Doors, Windows

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Log home draft & leak diagnosis:

This article explains the cause, detection, and cure of leaks on solid-log homes such as at cracks, checks in logs, log wall corners, at log wall windows, doors, sills, and eaves. Errors in placement of log splines, gaskets, or caulk are discussed along with various remedies.

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.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Where to Look for Leak and Draft Problems at Log House Windows, Corners, & Log Splines

Measuring a leak point in a log wall at a window jamb

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.

The windows in this new log home (shown at page top) were installed with no spline/gasket seal between the ends of the wall logs and the window jambs.

Our photo (above/left) 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.

Checks in a log wall cause window leaks

The photo above and a second photo below 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.

Measuring checks into a log wall

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.

Inspecting log home corners

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.

Inspecting log house for leaks at corner

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.


Continue reading at LOG HOME CONSTRUCTION or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see these

Log Home Articles

Readers whose homes are drafty, leaky, or otherwise too cold and who have high heating bills should also see these air leak articles:





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LEAK DIAGNOSIS & CURE in LOG HOMES at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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