Replacing block under interior support post

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  #1  
Old 04-17-16, 06:26 AM
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Replacing block under interior support post

When I had my home inspected before purchase the inspector noted that a block under one of the interior support posts in my crawl space is cracked and in need of replacement. I measured the blocks and picked up 2 of these as replacements (they are the same height as the old blocks):
http://www.menards.com/main/building...39954280633372

I was thinking I could use a 4x4 and a bottle jack to temporarily relieve pressure on the post so that I can slide the old blocks out and put the new blocks in. Does that sound reasonable? Anything else I should consider or be aware of?

Thanks in advance.
 
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  #2  
Old 04-17-16, 08:03 AM
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Welcome to the forums!

That's normally how it's done. Fasten the bottom of the temporary post to the jack so it can't slide off, and fasten the top to the framing for the same reason. Sometimes it's easier to fasten a piece of 2x 6 or 8 to the post to provide a way to temporary attach it to the framing and to spread the lifting force across more area. Jack it very slowly and just high enough to be able to slide the old blocks out. If you jack it too much you may crack drywall or the like. Make sure the surface under the blocks is even and smooth so the block is well supported or it might just crack again.

Good luck!
 
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Old 04-17-16, 08:09 AM
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The strength of the block is not indicated. It only says that is determined by the minimal use and not for all uses. It is a way around giving the guarantee that it is adequate for some uses. - I wrote the specs for concrete masonry units for 20 years and there always a problem of manufacturers making vague claims of usability.

If you use that size unit, dig down and make sure the soil base is well compacted. Even a thicker solid steel plate was used, there could still be differential settlement that could cause problems down the road. The fact that the old units cracked indicated poor soil compaction under the old units. Very often the soil around a home is quite loose and uncompacted and just dumped in and leveled off.

Dick
 
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Old 04-17-16, 08:10 AM
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Would not be legal or exceptable to do it that way any place I've ever lived.
To do it right you need to pore a real footer for the blocks to rest on.
A real footer in most cases is 24 X 24 X 8" thick with rebar in the center.
That block you posted is just going to sink over time.
 
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Old 04-17-16, 08:17 AM
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I forgot to mention that there is a footing underneath the blocks. The blocks sit on top of the footing and the post sits on top of the blocks.

[EDIT] Here is a pic

Attachment 65182
 
  #6  
Old 04-17-16, 08:32 AM
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Fasten the bottom of the temporary post to the jack so it can't slide off
Thanks! What is the best way to fasten the post to the bottle jack? Bottle jacks just have a small circular plate on the lifting surface so I'm not sure how I would make that work. Should I use a different kind of jack?
 
  #7  
Old 04-17-16, 12:12 PM
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Maybe it would be better to use a Jack Post like this instead of the bottle jack?

Tiger Brand Super S Series 3 ft. Jack Post-J-S-36 - The Home Depot
 
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Old 04-17-16, 12:21 PM
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The pic I posted earlier seems to be broken. Here is another pic of the post with the block underneath it (and footing below that).

Attachment 65186
 
  #9  
Old 04-17-16, 01:15 PM
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That's a little scary Nothing really holding it in place.

I suggest you just replace the existing post and blocks with an adjustable Steel lally column (the correct height to replace the whole shebang). They come in any length you need. Looks like there is room on the footer to put it right next to the old one, depending on what it is supporting above. You can use concrete anchors to fasten it to the footer and appropriate fasteners for the beam or framing above. Adjust it up enough to just take the pressure off the old post and remove the old post and blocks.
 
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Old 04-17-16, 02:52 PM
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I suggest you just replace the existing post and blocks with an adjustable Steel lally column
Interestingly, I think there actually is one of these just a few feet (on the same footer) from the post I'm working on. In this room there are 2 wooden posts on blocks and each of those has 2 adjustable columns within a few feet of them, though the steel columns are holding up a different joist. The wooden posts still appear to be bearing some weight but I'm guessing that it's not much. Can you help me understand why you changed your suggestion from just replacing the blocks to replacing the post completely?

Is this the type of support you are suggesting?
http://www.menards.com/main/building...815-c-5725.htm
 
  #11  
Old 04-17-16, 03:31 PM
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Please post a picture of what you have so we do not have to keep guessing.
There is no need to "attach" the bottle jack to anything.
I just use a 2 X 12 on the ground and I had a simple 1/2 thick steel plate 6 X 6 that I welded a short section of 2" pipe to that just sits on top of the piston to increase the surface area where it does the lifting.
I've lifted two story buildings with 50 ton jacks this way and never had an issue.
In most cases I've used a double row of solid concrete blocks for piers.
 
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Old 04-17-16, 03:54 PM
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Please post a picture of what you have so we do not have to keep guessing
There is a pic in this post:
http://www.doityourself.com/forum/fr...ml#post2524793
 
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