Solid wood beam with significant crack split or checknig © Daniel Friedman at Evaluate Cracks & Splits in Wood Beams or Posts
Cause, Effect, & Dealing with Checking Splits in Wood Beams or in Solid or Milled Log Home Walls

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How to evaluate cracks or splits in wood posts, beams, or logs such as in a log home.

This article defines, illustrates, and explains the cause and significance of splits or "checking" in wooden posts, wood beams, or in logs and beams used in log home structures.

Here we provide a guide to diagnosing and evaluating the impact of splits or checking found in wooden posts or beams or in logs of log homes.

Checking or splits in wooden posts, beams, or 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.

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.

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.

Evaluating Splits & Cracks in Wooden Beams, Posts, or Logs

Extreme bend in a wooden post at a basement stair © Daniel Friedman at InspectApedia.comThis article describes splits that are found in horizontal wooden beams (photo above), vertical wood posts, and in logs used in log homes.

While extreme loading can cause a wood beam (or more rarely a post) to split and would indicate a sign of impending disastrous collapse, usually the splits or cracks found in wooden posts and beams are due to shrinkage as wood dries, occur along the grain, and do not raise a structural concern.

An example is seen in the checked beams of our ceiling beam photo above and another example shows up in the cracks or splits in the logs of a log home discussed below.

[Click to enlarge any image] Photo: a bending, cracking, and failing wood post by the stairwell of a pre-1900 home in New York. This post is seriously damaged, risking structural collapse. This is not mere wooden post checking.

Article Contents

Splits & Cracks, Sags & Failures in Wooden Beams

Splits in a ceiling beam © Daniel Friedman at

While extreme loading can cause a wood beam to split and would indicate a sign of impending disastrous collapse, usually the splits or cracks found in wooden posts and beams are due to shrinkage as wood dries, occur along the grain, and do not raise a structural concern.

An example is seen in the checked beams of our ceiling beam photo above and another example shows up in the cracks or splits in the logs of a log home discussed below.

When a wooden beam is failing from rot, insect damage, or excessive loading, it may also split but you'll see that the split is very different, showing visible breakage of wood fibers and sagging in the span of the beam.

Sagging wood beam in an old barn © Daniel Friedman at

Above: there is a bit of sag and some checking in the wood beam above the yellow arrow in our photo.

A closer look will be needed to see if this beam is actually failing. In wood-framed structures, leaks, rot, and insect damage play important roles in the failure of wooden structural members.

In older structures such as the post and beam framed buildings shown above and below, failures at connections can lead to structural collapse even if the rest of the wood framing member is intact.

Wood beam failure © Daniel Friedman at

Above: this wooden beam is failing and collapsing from insect damage and possibly rot.

An Owner-Builder's Guide to Shrinkage In Log Home Walls

Log splits or checks in a log home

[Click to enlarge any image]

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 or Splitting - Are Log or Beam Splits A Structural Concern on a Milled Log House?

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

What Other Problems Might Be 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 in logs leak into the building © Daniel Friedman at

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.

Checks in logs leak into the building © Daniel Friedman at

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

Evaluating Splits or Cracks in Wooden Posts

Collapsing wood posts in an old NY Barn (C) Daniel Friedman Taurozzi

As long as they can be characterized as typical wood-post or wood-beam checking, those splits found in vertical posts are not a structural concern.

Placed vertically the post is in compression. Checking cracks in a post such as the 6x6" pressure treated deck post shown here are not going to be flagged as a concern by your building inspector, deck builder, nor other experienced field investigators.

Watch out: While checking-cracks in a vertical post are harmless, as we illustrate just below, overloading, rot, insect damage, or side-loading can indeed cause failure of a wooden post and risks catastrophic building collapse.

In this photo we have a set of old locust wood posts that are bending and breaking as the whole building is collapsing. The root problem in this wood structure collapse-in-process is the inwards collapse of the concrete foundation wall.

Reader Question: how dangerous are these cracks in the posts supporting our deck?

Checking cracks in a deck post (C) InspectApedia Hector


I sent picture of my balcony [above and below], and I would like your opinion about the post in the picture it is 5.5”x5.5”.

It has a crack 1/8”,I don’t know how many year has been there .The dimension of balcony are 10’x10’ x10’ high - Anon by private email


Tall deck of unknown safety (C)

With the WARNING that nobody can conduct a proper safety inspection by email, and that other defects such as improper fasteners or improper construction can certainly cause a fatal deck collapse,

The crack in your photo in the center of a 6x6 pressure treated post is common, it's called "checking", and it has no structural significance at all. Search for "checking in wood beams" to read details and to see more examples. Thanks for the photos - those may help other readers as posted here - keeping you anonymous of course unless you want to be identified as a technical contributor.

Watch out: Stay safe, don't fall off that ladder, and be sure that your deck was properly built with proper structural connections at all points, particularly to the building and between deck and posts; it should have had a building permit and a CO inspection.

Common causes of deck collapse include

Those are not details one can see in your photos. Less often (I think) decks collapse due to rot that in turn may be aggravated by improper construction or improper flashing.

Also be sure that the deck guardrails are safe, secure, well fastened, and at proper height and spacing. See GUARDRAIL CONSTRUCTION, STAIRS.

See DECK COLLAPSE Case Study for a detailed example of what can go wrong that causes a dangerous deck collapse.


Question: are the splits in this wooden post a structural problem?

Normal splits or checking ina a 4x4 inch wood post used indoors (C) NKOur home was built in 1979 and we have a support beam running from the first floor to the second floor that has a crack in it.

The crack has been there since we purchased the property five years ago and we're wondering whether it's a concern.

We didn't take any measurements initially so we don't know how much the crack has grown (presumably the crack would get worse over time).

As best we can tell, the crack extends inside to a third of the beam at the deepest point.

Some photos are attached. Any advice would be appreciated. - Anonymous by private email 2017/12/27


The photos look to me like normal checking that occurs in wood posts and beams (red arrow). Such spits can appear and even increase after original construction, as drying causes normal checking in a 4x4" or 6x6" post like that in your photos; it may have been installed while still a bit green or damp.

Your observation that the splits extend to a depth of about 1/3 of the post's thickness is consistent with this opinion.

Only if a post were split clear through, so that you could see daylight right through the thickness of the post, would I be concerned about its adequacy.

Watch out: however I do have a different structural question or possible concern: the post appears to support an overhead beam composed of two 2x10's or larger, spaced about an inch apart. I cannot see anything that actually connects the post to the overhead beam (orange circle), and I cannot see how the two 2x's, spaced apart as they are, are connected together.

Such a spaced beam may be have been specified and designed by an engineer or architect and might be perfectly adequate.

But when I cannot see a post-to-beam connection and when I see the overhead composite 2x lumber components that form the beam are spaced apart with no visible blocking nor connections between them, I am left questioning how the structure is held safely together besides more than gravity.

Reader Question: should I worry about the huge crack in this log beam?

Significant checking cracks in log beams & truss components (C) BB InspectApedia.comI own a home that was built in the 70's and the construction is cedar on the outside and pine walls and maple floors on the inside. The trusses are round logs bolted together.

I have lived in my home for 27 years and the cracks in two of the beams are now deeper and longer than when I first moved in.

[Click to enlarge any image]

I read your information about the logs drying over time causes the cracks to develop, but I still felt the need to send you two pictures showing the worst crack in one of my beams. This crack is 1/2" wide by 2 1/2" deep by 7 1/2 feet long.

The log circumference is 24 inches, diameter 8 inches, and the length is 26 feet. Should I have someone take a look at this crack or is it something I should not worry about? Is their a clamp made that would fit around this beam and help reduce the crack from expanding more?

Reply: probably not; here are some log checking crack or gap evaluation tips:

Normally even severe log checking is not a structural problem; it's cracking along the grain of the log, almost never continuing all the way through the log body, and is a normal result of building with wet or green logs. Most checking occurs in the first year or two of construction, though if that wasn't noticed until some time later it might give a false suggestion of new cracking.

Given that one of the horozontal logs has large "crack" near a bolt connecting to a log truss member I can see why you'd have been concerned. While I'm not a structural engineer, I'm experienced with this question. In my OPINION:

IF you saw evidence of new (since construction)

would I be more-concerned; in that case some reinforcement, banding, or re-connection might be in order.

Damage from checking that happens to occur where a bolted or other log connection is actuallly jeopardized could be a reason to add an iron band or clamp.

Reinforcing bands added to severely-checked log beams (C) InspectApedia.comReader Follow-up: added clamps around split log beams

I decided to have some large clamps made to put around the cracked logs. I am glad to see it was one of your suggestions. My wife feels better now that the clamps are in place.

Mod reply:

OPINION: Certainly clamping as you did won't hurt. The health benefits of peace of mind would be worth the cost.

When I have inspected, on-site, such checking cracks as those in your photos, I've probed crack depth, measured for sagging (easy, using a string and level), and I've taken care to check the connections between structural members.

Even though those cracks in the horizontal log look scary, I suspect that none of them goes more than 50% through the log - usually they stop before the log heart.

It's a basic concept of wood structural members (though not, perhaps obvious to a normal person), that the center of a wood beam is at close to zero stress. It's the upper and lower portions in compression and tension (if the load is down) that are doing the work.

That's why, I suspect, a structural engineer who is expert in log beams would tell us that even though the splits or checks in these logs run diagonally rather than straight along the log center, these checking cracks are rarely a structural concern.

Watch out: The exception might be a checking split or crack in a log or beam that runs right through a bolt connection.


Continue reading at ENERGY EFFICIENCY of LOG HOMES or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see DECK COLLAPSE Case Study


Or see FRAMING DAMAGE, INSPECTION, REPAIR - home - for advice on looking for damaged, unsafe wood structure framing


Or see ROT, TIMBER FRAME for a discussion of the cause and prevention of log checking during log or timber dry out, and for a case study of rot in timber frame construction.




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CRACKS CHECKS SPLITS in BEAMS, LOGS & POSTS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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