Deteiorating CMU piers

**Randall Clark** · 05-04-2021, 06:58 PM

This home is just under 30 years old and multiple piers under the home exhibited deterioration at/just above the soil line. When probing, they were relatively stable and there was no notable deterioration below soil line and down about another two inches. Crawl space was not unusually damp at time of inspection and no visible signs of long-term moisture problems. Thoughts on causes, significance and any mitigation needs?

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**Dom D'Agostino** · 05-05-2021, 03:52 AM

So it's the footing that's "soft" and crumbling, not the CMU's?

**Jerry Peck** · 05-05-2021, 08:53 AM

Do you have a side view photo of the pier?

Are the CMUs solid?

It is unusual, at least for me, to see the CMUs laid vertically rather than horizontally.

Neither the CMUs nor the concrete footing should be falling apart.

**Randall Clark** · 05-05-2021, 05:23 PM

Originally Posted by Dom D'Agostino

So it's the footing that's "soft" and crumbling, not the CMU's?

The footing is well below grade, so what you see is the CMU.

- - - Updated - - -

Originally Posted by Jerry Peck

Do you have a side view photo of the pier?

Are the CMUs solid?

It is unusual, at least for me, to see the CMUs laid vertically rather than horizontally.

Neither the CMUs nor the concrete footing should be falling apart.

These are likely solid.

**Dom D'Agostino** · 05-05-2021, 06:45 PM

Originally Posted by Randall Clark

The footing is well below grade, so what you see is the CMU.

That 1st row in the photo looks like a different mix or different product, I thought it was the top of a poured footing.

**Jerry Peck** · 05-05-2021, 06:58 PM

That looks like the aggregate in concrete more than it does in a CMU?

Again "Do you have a side view photo of the pier?"

Showing all sides of the pier may help.

How deep down is the top of the footing?

**Randall Clark** · 05-06-2021, 06:14 PM

Originally Posted by Jerry Peck

That looks like the aggregate in concrete more than it does in a CMU?

Again "Do you have a side view photo of the pier?"

Showing all sides of the pier may help.

How deep down is the top of the footing?

I do not have a photo of the side of that pier but in the first photo, you can see the side of the adjacent pier. I did not probe to the top of the footing, but most in this area are about 12" below grade.

**Jerry Peck** · 05-06-2021, 07:40 PM

Originally Posted by Randall Clark

I do not have a photo of the side of that pier but in the first photo, you can see the side of the adjacent pier.

I thought that was part of a wall, okay, got it, which brings up a continuation of one of my initial ponderings: the pier viewed from the front shows the (likely solid) CMUs stacked on edge; the pier viewed from the side (the pier to the left) shows that the second course (next course up) of CMUs up is also stacked on edge perpendicular to the first course.

Being as the CMUs are square, laying the CMUs flat and stacking them one above the other would use the same number of CMUs, but would create a much more stable pier (gravity works for you, not against you) versus a pier made with CMUs stacked vertically, with more CMUs stacked vertically on top.

Any engineers out their? What do you say about stacking thin, square, CMUs vertically on edge versus laying them flat on top of each other?

**Randall Clark** · 05-30-2021, 07:46 AM

Update. this is what an engineer said after looking at the photos:

The damages to the foundation piers is a little unusual. The photo appears to show two adjacent concrete block piers with surface damage to the level of block that projects above the ground surface. The appearance of the damage was characteristic of a condition known as spalling. The fact that more than one pier is involved suggests an environmental source rather than a material failure. My best guess is that this is freeze damage. This may occur if a hard freeze follows a heavy rain that saturated the lower layer of block before the first floor is constructed. The portion of block below the surface is protected from the freezing temperatures, and the next layer of block above did not get saturated enough to cause spalling.

The significant of the damage and whether or not some repair might be appropriate is difficult to judge from a photograph. If the piers were filled with grout or mortar, the damage is of no concern. If they were not, the bearing capacity of the piers was reduced to some degree. What I cannot determine is whether the capacity was reduced to any significant degree. If the piers were not filled, the most economical solution would probably be to fill the affected piers with grout.