Tuesday, February 16, 2016

How to know if you have a "cracked slab".


The answer is, if you have a slab, it is cracked.  But don't mistake those cracks in your slab to a non-functioning slab.  I severely dislike the term cracked slab.  It makes my skin crawl.  Every slab foundation that has ever been built without a doubt has at least one crack in it.  But, those cracks do not necessarily make it NONFUNCTIONAL. 

Cracks associated with foundation distress don't only appear in the slab, but they will also be present  in the drywall, flooring, brick, mortar, frieze boards, window trim, and door trip.  Non-functioning slabs will have angles in them.  And those angles will appear in what is built on top of them.  Doors will stick, doors will close on their own.  Windows won't fit in the brick veneer correctly anymore, with visible gaps on the side of the window. Windows won't open properly.  Cracks will appear in diagonals, straight lines, and vertically.  Each one of these types of distress will tell you a story as to how the foundation is moving.  As we've discussed before, reading these signs is key to diagnosing what is going on with the foundation.

"Why does my foundation crack, if it's doing what it's supposed to?"

























There are many answers to this question.
  1. Concrete can crack from the process of drying. 
  2. Concrete can crack due to age.  
  3. Your foundation can crack because of constant, minor foundation movement from season to season.  These little movements can cause little cracks on your foundation along the "hinge points" which are interior areas that area stable or static (not moving).
  4. Corner Cracks will pop up in your foundation from moisture absorption and or thermal expansion. 
  5. Your foundation can crack from differential movement, putting the foundation under stress.
  6. Your foundation can crack because of massive temperature changes in a short time period.
  7. Your foundation from tensed tension cables.

Sometimes, these cracks can show through your foundation and into your flooring.  If you have tile/wood flooring that is glued down to the foundation, it can crack or separate as these cracks appear.  It will mimic what the foundation is doing, as it is bonded to it.  Carpet can show the cracks as well. In carpet, you can see wrinkles in the floor, or depressions in severe cases.

The problem I have with the term cracked slab is that, while it might mean you have a foundation problem, it doesn't ALWAYS mean you have a foundation problem.

"What do those foundation cracks look like/mean?"
I don't even know how to describe this crack!
Displacement Crack

Image result for foundation crack]
Hinge Crack
Drying or curing Crack
Image result for foundation crack]
This is a joint between two separately poured foundations.


Image result for foundation crack]
Corner Crack
Image result for foundation crack]
Exterior Gradebeam Crack
Stressed cap from post tension cable.


You can see from the pictures above, obviously there are varying degrees of cracks in a foundation, just like there are varying degrees of breaks in a bone.  Some of these are obvious foundation issues.  Some of them aren't necessarily.  Drying cracks are commonly seen in all forms of concrete, especially in driveways, sidewalks, and garage floors.  Flooring covers most of the surface cracks in your foundation, and if it's not removed most people don't even know they have cracks.  Before you let anyone tell you that your cracks in your slab mean you have major foundation problems, look at the rest of your house, and get a reputable, qualified foundation repair contractor or a structural engineer that can analyze and explain those cracks.  

Let me know if you have any questions, and thanks again for reading.

Brian
Perma Pier Foundation Repair

You can call us here: 877-554-6259

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Or you can email me directly with any questions at: brian.gilchriest@permapier.com