Foundation Crack Monitoring

Here is a free graphic showing a witness mark documenting a crack with on a specific date:


the inspector would not come back. it would be up to the homeowner to monitor the crack for movement.

Great idea. Witness Mark.
Thanks Randy.

Thanks again, Randy. :slight_smile:


Always like to see the “insider” stuff.

What is the 2" ?? Wide / Long / Etc

the 2" line is there to measure over time. if the line ever measures more then 2" then the crack is moving.
the other # is the date. for reference.

the line goes over the crack. just like in the Graphic.


Correct. Measurement of the horizontal line between the intersections of the vertical lines.

@rmayo , maybe you should add a tape measure graphic showing the measurement made.

Did not know if it meant long or what (sure wasn’t 2"wide)

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Also will visualize any settlement.

Anybody do this for home inspections?

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I did occasionally.


I saw that during an inspection, it was about 6 years old. I measured between the lines, and it was about 1/4" wider that the dimension marked on the wall. However, there was barely enough of a gap in the crack to put more than about 3 pieces of paper in, so we weren’t sure what it proved. We figure they did a poor job of marking the reference lines.

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From a structural engineering perspective it’s beneficial to know the when the crack occurred and if it’s still actively moving. A 1/4” crack in a one year old foundation could be a bigger problem then one in a 50 year old foundation. The size, location and width are just pieces of the puzzle. Adding two more puzzles pieces like when the crack occurred and how long it took to get to its current size can make all the difference on what needs to be done. A big crack over a short period of time typically needs immediate attention whereas the same crack occurred 50 years ago and hasn’t moved in the last 40 years just needs monitoring. If a crack is actively leaking that issue has to be handled separately. The witness mark is only a tool to establish if a crack is still active, and how fast it’s moving.


I never did, neither have I seen cracks marked as shown. However, I can see the value in measuring and marking the crack.

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I love the idea of a 2" in marker for future reference. My questions about this would be…

  1. Is the crack the same width from top to bottom?
  2. How old is the house and crack itself?
  3. Is this an exterior or interior wall?
  4. Who will monitor the crack?
    Just a few thoughts. From first glance, you are right in only recommending monitoring the crack.

I would only recommend this for a variable width settlement crack, which is typically wader at the top, which is where the witness mark should be. Not need for common shrinkage cracks. Age of house doesn’t matter, the purpose is to determent if the crack is moving and how fast. The witness mark is typically on the inside basement wall or outside on a crawlspace wall. I prefer pencil, which seems to last longer. This is for the homeowner to monitor.

Hi Keith I do this often.