Replacing Cinder Block Pier


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Old 01-28-14, 05:08 PM
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Replacing Cinder Block Pier

Hello,

I had nothing better to do the other day and went crawling around in my crawl space and to my surprise one of the piers was pretty much destroyed. I have my theories as to the why but I am wondering about the possibility of a pretty resourceful DIY'r like myself taking on this type repair. Currently I have a 18000 pound jack next to it for some type of relief. See the pictures and any suggesting are greatly appreciated. Is this something that can be done correctly and safely by a do-it-yourselfer ?

Thanks for all feedback.
 
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Old 01-29-14, 12:21 AM
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With proper skills and enough knowledge, such a repair/replacement can be easily accomplished by a DIYer. Probably the most important thing to know is why the original pier failed in the first place--you don't want to work hard on a fix, only to have the same thing happen again in a few years. The pix would indicate that hollow CMU blocks were used, which is not something I'd rely on to support more than minimal loads. Far better to fill with reinforced concrete, or even use heavy PT timbers (loaded parallel to the grain) bearing on stout concrete footings if moisture problems aren't an issue.

An important factor is getting a tight fit between the load-carrying beam and the new pier column. I prefer slightly and slowly jacking the beam (no more than 1/8") and building the pier to just below tight-fit elevation, then letting the jack(s) down gently to bear against the new support. I've lost count of the number of smashed timber shim plates I've seen over the years, from people trying to beat them into place who don't know any better--splinters make very poor bearing surfaces.
 
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Old 01-29-14, 04:08 AM
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Thanks BridgeMan45 - Not shown in the picture IS a shattered wooded shim on the top, so interesting that you mentioned that.

As far as jacking the load-carrying beam, what type of surface can I use? Meaning, is a solid concrete block good enough to sit under the jack while I replace this pier? I am planning to have two jacks - one on each side... thoughts? Thanks in advance!
 
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Old 01-29-14, 04:23 AM
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This question is as much for BridgeMan45. Is a steel lolly column an acceptable replacement for the pier? They are commonly used in basements but I rarely see them used in crawl spaces.
 
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Old 01-29-14, 04:25 AM
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A solid block or piece of wood, basically anything that will disperse the load so the jack doesn't sink. What works best will be determined by the soil conditions. As far as I know all the block piers under my house are hollow and I've not had any issues but like BridgeMan said - a lot depends on the load. I assume you have a good footer under the pier in question ??
 
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Old 01-29-14, 05:40 AM
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Anyone notice the bricks inside the blocks?
Looks like someone tried making there own solid blocks.
Do those blocks run parallel with the beam it's suppose to be holding up like there suppose to be?
If not the beam is acting like a wedge trying to split the block.
 
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Old 01-29-14, 06:42 AM
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Interesting statement joecaption1! I think you are correct, the blocks do not run parallel with the beam. I attached a crude drawing from MS Word - this would be a bottom up view. So you are saying the blocks should be turned 90 degrees? Also, those bricks originated from the inside of the block.
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Old 01-29-14, 06:46 AM
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I am not sure about the "good footer." I am guessing the only way to find out is by removing the existing pier??
 
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Old 01-29-14, 07:00 AM
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You can dig along the bottom of the block to assess the footer. I wouldn't think the orientation of the block would be a big deal providing there is either a solid cap block at the top of a 2x8 to disperse the load. ...... but I'm a painter, not a builder so I could be wrong
 
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Old 01-29-14, 08:38 AM
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The footer should have been a 24 X 24" X at least 8" ( some places call for 12") thick pored footing, even better if there was 4 pieces of rebar in the middle of the pore.
BY turning the block it spreads out the load. The way it's sitting now the wood beam can compress into the wood.
 
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Old 01-29-14, 09:50 AM
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Steel lolly (or lally, depending on what part of the country one is in) columns can be used in crawl spaces or basements, provided those made of cheap, thin material are avoided. I wouldn't use anything less than Schedule 40, 3" dia. pipe myself. I suspect a reason they aren't used more in crawl spaces is the tendency for them to corrode (especially at the bottom, where internal condensation collects if they aren't filled with concrete) to the point of rusting completely through. The interior surfaces of several I've seen with 100% section loss don't appear to have ever been painted, either, contributing to more rapid corrosion yet. Temporary jack posts should never be used for permanent installations; codes don't allow it, and manufacturers don't recommend it.

The orientation of CMU blocks is important. Long direction should always be parallel to the beam, not perpendicular to it. The reason is that bearing stresses in the block's concrete can be more than doubled for a constant load if only a minimal area of cell walls are carrying that same load, instead of all cell walls of each block. This is shown quite clearly in the sketch provided by the OP.
 

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Old 01-29-14, 11:27 AM
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You guys have been extremely helpful and have given me a dose of confidence regarding the taking on of this job. As I proceed I will be taking and posting pictures on a regular basis so those interested in "helping out" please subscribe. Does anyone know of a good online reference detailing the "how to" of a job like this? especially one in such cramped quarters as a crawl space.

Thanks in advance and stay tuned for the pictures.
 
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Old 01-29-14, 11:52 AM
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If you dig down to see the footing size and type. After all. the footing is stronger than the unreinforced "cinder" block since the hollow block failed because the footing was stronger than the hollow block. What is under the temporary post looks strangely like the block the 16x16 block that are sold for temporary use.

You may find out that it will be easier and cheaper to use the footing and jack up the beam 1/8", put in a some new block filled solid and even a spreader beam (belt and suspenders engineering) to pick up more floor load.

The thickness of the footing may not be that important since an 8" thick footing only needs to be larger than 4" wider than the bearing column, even if unreinforced. The prescribed footing sizes are ease of use and inspection, but anything thicker is for show and over-kill and could transfer more load than the soil could accept. - Engineering is a matter of balanced loads and stresses to avoid localized problems and settlement. The key to pier construction is balanced loads and deflections between the individual piers.

A few inches of digging could save a lot of grief and problems/troubles.

Dick
 
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Old 01-29-14, 03:20 PM
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Obviously from your statements and screen name you know what you're talking about, any ideas about locating instructional resources online that fits this job?
 
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Old 01-29-14, 07:23 PM
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Forget the online resources--just invest in a quality pair of knee pads, and get down there and do it! You should have enough knowledge from the previous posts to complete the job successfully. And if any questions pop up that you don't know how to deal with, just come back to this forum for a (relatively) quick answer, or three, or ten.

A note of caution about online resources--I've lost count of the number of both online "how-to" videos and renovation programs on TV I've briefly looked at that are totally inept and incomplete. Some are bad enough to get people and their homes into big trouble, or seriously hurt themselves. You don't need that.
 
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Old 01-30-14, 05:40 PM
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All right. This should prove interesting. I am having an engineer come over for 250.00 and assess and provide a drawing as to what "he" thinks needs to be done (obviously the one pier).

I am thinking if there are other issues that are bound to occur soon I might as well address them as well. If the thread remains active I will be posting the engineering drawing and photos as things progress. The engineer will be here on Tuesday the fourth and hopefully I can get the drawing from him soon there after.
 
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Old 01-31-14, 06:22 AM
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imo, bridge, dick, & joe nailed it but have a ? for bdge,,, i though lalley columns were conc filled for fires as they would be less likely to collapse under hi temps.

we use sched 40 steel pipe - shims are also steel
 
 

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