Originally Posted By: Jeff Tooke This post was automatically imported from our archived forum.
As an appraiser, I occasionally see residential foundations in the Midwest that have block walls that are cinder block or some type of reddish clay block. I am seeking information on the reddish clay block as well as the cinder block. Are they the same? What are they called? The last house I saw the reddish clay block in was built in 1918. The basement was damp and there was damage to the block in the form of flaking. I would appreaciate comments from anyone with experience in inspecting this type of foundation as to the plusses and minuses. From the appearence it seems the compression strength is not there. Do they eventuall deteriorate? Thanks in advance for your time and comments.
Originally Posted By: kmcmahon This post was automatically imported from our archived forum.
If it’s clay, it’s different than what I’m thinking, but they do make masonry block and use dye of different colors to get a different look to a structure. (and red is one of the colors)
Originally Posted By: Guest This post was automatically imported from our archived forum.
They are a fired clay material. Normally one side is striated to hold a parge coat. They were used with either face exposed to the outside, a smooth glazed face which was usually left unfinished, or the striated face which was normally parged, plastered or stuccoed. They were very popular around the turn of the century and were inexpensive, effective and durable. In the mid 1920’s they were replaced by “cinder” blocks which were less costly to produce.
The clay tiles are still in good use today and their main weakness is susceptibility to freeze thaw damage if the glazed face is violated. If the face is intact chances are they haven’t aged one bit.
As far as compressive strength goes they must be close to CMU’s becuse I’ve seen 5 story buildings built out them with no other supporting structure.
Originally Posted By: mcraig This post was automatically imported from our archived forum.
I pride myself on doing Historic homes here in Arizona And have not seen these. I now have learned something new are there any pictures of these blocks?
Originally Posted By: Brian A. Goodman This post was automatically imported from our archived forum.
Yow! Sorry about the size, I thought I shrank it more than that.
Before someone asks, the holes are from the termite guys. They bored 1/4 inch holes from the outside, but were apparently leaning on the dang drills so hard that when they broke through they broke right through the back side. This house was built in 1927.
Credit for the correct term (structural terra cotta) actually goes to William Kibbel, an old house inspection expert. I learned it from him.
Originally Posted By: Jeff Tooke This post was automatically imported from our archived forum.
Chad really nailed it. The picture shows it well. The description of the use is right on as well.
I have looked at thousands of houses over 20 years and have only seen clay fired or cinder block foundations about 10 or so times. They have always been on full basements and of the 1920’s vintage of average size and quality residences.
I am not sure if it means anything, but it seems such foundations are more likely to be in small communities. Perhaps this attests to the absence of stone quarry or possibly to the portability of this lighter material.
Originally Posted By: roconnor This post was automatically imported from our archived forum.
Seems like that is older fired-clay tile block (or Clay Block) common in the 1920’s and 1930’s. Chad is right that it was a very durable and strong foundation wall material … but it is different from modern day Terra Cotta.
It was replaced by cheaper "Cinder Block", which had problems because of the iron particles in the aggregate they were made with (residue or cinders from the steel manufacturing process). Moisture would attack the iron particles, which would cause corrosion and deterioration. Some also called those "Pop Blocks" because aggregate busting out of the block would actually cause popping sounds.
Around the 1950's Cinder Block was replaced by Concrete Block (CMU), which didn't have the same issues. To this day people still call CMU's "cinder blocks" ... but that's not really true because they are not made with the same cinders any more (kinda like calling modern day AC electrical cable "BX").
Just my 2-nickels ... 
-- Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: jmcginnis This post was automatically imported from our archived forum.
Hey Robert…
Here in the “Coal Regions” of Pa, they used to have lots of cinder block factories that used coal ash from anthracite to make the product. It also had a tendancy to break down over time and did not bear weight stresses nearly as well as cement block. I was wondering if you might know what type of block we used in the Navy over 30 years ago when we were building a foundations near a submarine port. We used to throw the 24 by 24 by 12 inch blocks in the ocean and they would float. We used to make some money on it by betting against the new guys who didn’t know any better.
Originally Posted By: rmoewe This post was automatically imported from our archived forum.
I add this to all of these types of foundations in my reports.
In the 20’s they used a poor type of concrete and mortar mix. The lime content was too high and will cause problems. This is the exact quote that I use in my reports.
"The foundation was constructed in the nineteen-twenties. The concrete and motar that was used at the time was a poor quality that has a tendency to soften and deteriorate due to its lime content."
You must also remember how long concrete and mortar is good for, before it will start to deteriorate.
