Cement Block Basement Wall with Ledge

Newer inspector here … I performed an inspection of a home built in 1980 today. The basement walls were cement block, 13 blocks high. About half way up (7 blocks up), there was a ledge around the foundation. Almost like the block wall went from 2 blocks thick at the lower portion, to 1 block thick about 1/2 way up. The thicker block begins at grade level. Is it just that the wall needs to be thicker (stronger) at the greater depth (possibly due to soil conditions)? I haven’t seen this in basements before - what I am familiar with is a basement wall with a uniform thickness. Appreciate the help!

Well, it is cracking and water is coming in at the bottom.

I have not seen before either. The concrete along the ledge appears to be green or fresh. Unable to determine if it was added at a later date or original construction. Any more photos?

Thanks Brian. Yes, I’ve seen the crack, and the copper tubing in the wall from an underground oil tank (confirmed removed). I think the ‘fresh’ appearance of the concrete is just shadows. I’ve attached another picture of the ledge, farther along the same wall, where the concrete on the ledge is closer in shading to that used as mortar in the block.

Nice shot of a radon pipe and manometer you got there.

I see nothing wrong with the extra course of block. What is your location?

Could the block wall be a rebuild of the original foundation… I am looking at the corner connection with the cut blocks when I suggest this. The original wall may have suffered from bulging, what is at the exterior of the wall?

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Not that odd, really. I worked on a $12 million in which the main house was 6" block at the first story and 8" block at the second.
A more professional term is “concrete block” or what architects use… “concrete masonry unit (CMU)”.

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We have a lot of cinder blocks where I am from, all around the old gardens and driveways.

Brian, as far as I know, “cinder block” is just a homeowner term for CMU. That said, you want your client to understand what you’re telling them, but if you wind up in court, you want your report to make it plain that you understand professional-level terms.

That is interesting. My grandfather would say to me, “that is an old cinder block, it ain’t good for nothing”. He would buy new block for real projects. Cinders were lying around for small stuff like putting a car on blocks, raised beds etc.

And I agree with you about terminology 100%

And for the record. I have never used the term cinder in any professional manner. But I will still grab an old cinder for for various needs :slight_smile: :grinning:

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is that Great Stuff foam crap or similar garbage at bottom of wall in 1st pic?

:55 mark, good ole foamster stuff here on inside lol

:50 mark… now video of the outside, hmmm, what was open that allowed water in

they paid $ somebody who added soil, did that work? lol

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Kenton, do you mean that in reverse?..8" 1st story and 6" 2nd story?

I have never see what you described.


Inspectors call out siding in contact with the ground. But it is not just because the siding will deteriorate but also because what you see here. That sill plate MUST be above grade! Had the sill plate been above grade, that big crack would also have been visible. That is a cool vid!!

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Yep, it is, Brian! Way to go , Mark!

Good educating for many. Thanks!


If an acrylic fortifier was used in the grout mix, it would leave it looking “green” for a long time. I’ve seen it turn almost blue a few times when alot was used. I used it quite a bit back in the day parge coating on commercial buildings around elevated docks.

I was taught years ago that “cinder block” used pumice for the aggregate since it can withstand alot of heat and used in fireplaces. Could be way off base but like I said, it’s what I was taught 30+ years ago…

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Cinder block used coal “cinders” for the aggregate in the concrete block instead of stone. Coal cinders were plentiful back when coal was king. Coal was used in heating homes and powering thousands of locomotive boilers. While cinder block was lighter than its stone aggregate brother its downside was that under the right conditions it is flammable. After all coal cinders are partially unburned pieces of coal (the fragments that fell through the grate).

With the advent of oil heat, diesel/electric locomotive engines and more efficient coal plants after WWII coal cinders became a thing of the past.


Great info Bob. Thanks :+1:

Likely went from a 12
’ bock below grade to an 8" block above grade. The radon company likely filled in the open cells at the top of the block ledge to prevent radon gas from entering the basement.

Nice one! Agreed.

So what is going on with this area that is not shelved?

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The OP has not put enough input into this thread. It looks like someone filled in an existing opening. A door, maybe?