Cinder Block foundations

[Richard A. Hetzel]

Yes please do, it would be interesting to know what is wrong.

1. Cinder block would be unacceptable for such structural uses.
2. If the block is 8x16, then the pad below the block should be minimum 8 inches thick.
3. The "pad" (footing) must be sized to the load carried on the pier. Who knows whether the size shown is adequate?
4. The beam must aslo be sized according to the span and loads. Who knows whether a 4x6 is adequate?
5. There is no need to pour the footing around the block. The mortar between block and footing, and/or the reinforcing bars embedded in the footing, are adequate to resist lateral movement of the block on the footing.
6. The dimension of the footing, if poured around the block, is insufficient to prevent a stress concentration and probable cracking of the footing at the block corners.

Other than that, it's fine, except it's a good example of why the building department isn't qualified to design your structure.

There are things, very many things, about construction that one will not find in code books or by picking building officials' brains. The gulf between code minimums and good practice is often a wide one. That is why design professionals exist.

The first question is: are the piers in question interior or exterior piers? the second question is: is the region subject to frost? If they are interior piers in a region which does not experience deep frost, then placing the footing bottoms directly on grade may well be acceptable, and that in turn may depend on the exact soil characteristics in that exact location.

[jlybolt]

Richard, are you saying a structural engineer might be in order since there is noticeable movement of the piers on a 4 month structure as I stated earlier? For the most part the majority of the homes I have inspected with block piers show excess movement of the pier thus leading me to believe the footer or pad on grade is not the way to go. The builder uses this foundation to save on costs, seriously doubt he had a engineer come out tell him the footer on grade was o.k.
Thats why I am tryng to grather information on how to install a block pier.
From what I am gathering the best practice may to recommend evulation by an experienced foundation company.

Thank you everyone for your comments. Its been helpful.

[Paul Dickerson]

If there is significant movement at the foundation of a 4 month old structure, it doesn't matter how it is built. Recommend evaluation and repairs.

[Richard A. Hetzel]

since there is noticeable movement of the piers on a 4 month structure

Movement in which direction? Up? Down? Laterally? If it's up or down, it indicates a soil issue, and that issue will likely be present just as much a foot below grade as on grade. If the movement is lateral, what was the cause? Is the beam that rests on the pier twisted or bent laterally as well? Are there signs of distress in the house above which reflect lateral movement? Has more than one pier moved laterally? If so, is there any recognizable pattern to the movement? Lots of questions that need asnwers in order to answer your original question...by all means, refer if you have found something that isn't right.

[Kenneth Lott]

The footings are supposed to be below the frost line.

[Marcel R. Cyr]

Originally Posted by klott

The footings are supposed to be below the frost line.

Hey, Ken, this is Texas I believe. ha. ha.

How you feeling anyways?

Marcel

[Brian A. MacNeish]

Originally Posted by Richard A. Hetzel

1.
Other than that, it's fine, except it's a good example of why the building department isn't qualified to design your structure.

There are things, very many things, about construction that one will not find in code books or by picking building officials' brains. The gulf between code minimums and good practice is often a wide one. That is why design professionals exist.

Right on, Richard.

Here's an excerpt from the preface to the current National Building Code (NBC) for Canada:

The NBC is a model code that, when adopted or adapted by a province or territory, becomes a regulation. It is not a textbook on building design or construction. The design of a technically sound building depends upon many factors beyond simple compliance with building regulations. Such factors include the availability of knowledgeable practitioners who have received appropriate training and experience and have some degree of familiarity with the principles of good building practice and experience using textbooks, reference manuals and technical guides.

For the uninitiated: Some very important and informative eyeopeners in the above paragraph for anyone that takes the time to read it.

PS: This is probably why in the past 2 years I have been consulting on failures on 4 higher end houses up to $1.5 million. The present one ($800,000) has severe rot in 9 months!!!

[Richard A. Hetzel]

Bingo.

[John E. Gibson, #2]

I've seen and also owned a cottage with Pad and post type foundation. The pads had to be a min. of 6" thick and 24" x 24" square with rebar reinforcing. The posts if wood had to be treated 8" square. They did not have to be below grade. There was never a problem with lateral movement only slight frost heaving up and down. Had to level things every 4 years for the first decade then it settled in fine.Cinder block if on its hollow side ( normal orientation ) does not give much bearing surface on the top edge for a stringer to sit on. Cinder blocks if used as a single post, may crack or break under load when used alone. After all a small tap with a hammer and they shatter. If they were filled with cement could make a big difference.

[John E. Gibson, #2]

Someone posted a thread that the footing must be below the frost line. my best friend built his cottage with a basement and poured footings. The frost was over 8" down. We lived above the 56 parrallel. No one digs below the frost line there. Larger homes and buildings must put in piles and pour cement for footings. over 14 feet deep. Lots of new homes go up with crawl space type foundations and the footings are on grade or just slightly below. The area under the the home is heated with lighting or small space hearers and there is almost no frost heaving if insulated properly. Only trick is that the pads and posts must be inside the crawl space and not along the outside wall. Probably 2' in from the outside insulated wall.

[Kenneth Lott]

Originally Posted by mcyr

Hey, Ken, this is Texas I believe. ha. ha.

How you feeling anyways?

Marcel

They don't get frost in Texas? I'm hanging in there, going in Hospital for more test tommorow. Thanks

[Marcel R. Cyr]

Originally Posted by klott

They don't get frost in Texas? I'm hanging in there, going in Hospital for more test tommorow. Thanks

Good luck to you tomorrow, and frost in Texas, last time I was there in April, there did not seem to be any. ha. ha.

Marcel

[wkish]

In my neck of the woods [fla] a pier or colum most times 9 of 10 the footer is usualy 3'x3'x3' the easy way to ck is to remove some sod carefully or brush away the soil, if you can see a footer shape then you can asume it was done right

[Larry D. Kage]

Originally Posted by wkish

In my neck of the woods [fla] a pier or colum most times 9 of 10 the footer is usualy 3'x3'x3' the easy way to ck is to remove some sod carefully or brush away the soil, if you can see a footer shape then you can asume it was done right

Wow!...that's a yard of concrete per pier/column...seems excessive.

[Brian A. MacNeish]

Originally Posted by lkage

Wow!...that's a yard of concrete per pier/column...seems excessive.

For a house with average point loads and soils good practice would be:

the thickness of pad be 1/2 its horizontal dimensions and rebar installed. 36X36" does seem excessive for a house. Most I've seen are 24 x24 x12" or 16 x 16 x 8"