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Building "basement wall" to support house weight. Top row of block issue

3K views 10 replies 5 participants last post by  RWolff 
#1 ·
Hello, I started building a block wall using 8x8x16 inch standard concrete blocks. This wall goes under the corner of my house with no real access from the inside. However, I would like to put some of the house weight on this new section of wall but I'm not sure what a good way to do this might be.

I have about a foot of space left to work with. I have two 4 ton bottle jacks that i was planning to set on the wall and raising the bottom of the house about a 1/4" putting in the last rows of block and then releasing the weight back onto the block after it's dried. I'm just not sure how to do it.

Any ideas? :help:

I attached a diagram and some pictures to give you a better idea of what I'm talking about.
 

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#4 ·
Ignoring or not considering your basic foundation structure or its present support.....or this support......

But just adressing how to get your block up under your framing tight, I suppose you could jack it slightly and slide block under it..... or you could just put your block in and then use "dry pack" mortor to fill the void.... it will build and pack in there tight....drys immediately... doesn't shrink...and has plenty of compressive streanth...

Just a thought
 
#10 ·
I dont think you ever answered MTN's question and I am still wondering as well. What exactly is holding up this corner now? Is all of the weight carried by one or two of the floor joists?

As far as how to finish this, If it was mine, I think I would lay 4 x 8 x 16 pancakes (Solid Block) perfectly level in type S mortar that has been rehydrated to reduce shrinkage under the bearing end of the joists. I would size the space between the solid blocks and the sole plate as close as possible to the exact size of a steel I beam. I would jack the corner ever so slightly, and then pound the I beam in with a sledge hammer, and let the addition down on the beam. Pre drill the lower and upper flange of the beam to anchor the I beam to the sole plate and to the pancakes. Double the end joist on the wall that runs with the joists, and fill in with block, as Jomama says, and top with a PT plate. I really think this is the only way to get full bearing on the foundation, as all mortar shrinks to some degree.

Sorry, best I can do, as I am not used to reverse building, just trying to offer a possible solution.
 
#3 · (Edited)
No, it's the interior basement walls. I also have two supports I made from stacking blocks on top of each other and then using some wood shims to get it nice and tight. That's holding it for now.. before it was just the interior walls and the 4x4 wood post! Apparently, that was "working"
 
#7 · (Edited)
That's a great question actually... One that I would like to ask the person that did it in the first place, along with my other list of questions about why they did what they did. I'm just trying to fix there :censored: work the best I can. I never did this before but I think I'm doing pretty good. Only time will tell but I'm trying to do it to the best of my knowledge and ability. I like your quote. hehe
 
#9 ·
Your next course should be 8" solid top block, leaving you 4" to fill, which is ideal for 8" half-course solids. They might seam too heavy for what you're doing, but having solid surfaces is going to be much easier to snug the last course in nice and tight with just plain mortar. There's easier ways to do this, but I can't think of any that apply easily when you have no access to the inside...........
 
#11 ·
I had a similar issue with my kitchen on the corner of the house which was originally a 10x24' back porch that had no foundation or basement under it.
After digging out a basement under it I built a block wall similar to the photos. I used solid blocks for the top course.
I had to jack the corner up a little higher, maybe 1/2" than it's final height was to be, and then once the mortar had set I laid a couple of 2x8 boards down, and lowered the jacks the 1/2" so the joists were resting on the 2x8s which I screwed down to the them.

You might need thin pieces of material to shim the height you need, but the upshot is you wull need to jack a little higher than finished height to allow for the weight to settle and compress.
 
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