So I am buying this “mansion” 2500 sq f, main floor is probably 26 by 50′ full basement. South wall of basement, concrete block, seriously bowed. crack is visible along most of the 50′ wall at 5 courses down. Bottom 7 courses out of plumb, top 5 seem plumb but probably shifted (slid) in a few inches. Maybe 2 inches out of plumb for the bottom 7 courses. Block looks good. If I excavate this down to the footings, jack up the house, can the foundation be “persuaded” back into plumb? The soil is 100 % sand, but small overhang and NO GUTTERS! Obviously the first thing I’ll install is gutters and doubt this will happen again once we get drainage in place.
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
Learn more about the benefits and compliance details for the DOE's new water heater energy-efficiency standards.
Featured Video
Video: Build a Fireplace, Brick by BrickHighlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
Block looking good doesn't seem to be germane to this problem. Get an estimate for a professional fix. Take that off of the amount you were willing to pay for the house.
Renegotiate and have the problem fixed. I would remove the foundation that is affected after jacking to level. Then I would start over with the foundation. Use the old block for landfill.
Thanks Sasquatch,
this is exactly what my buddy is suggesting. Problem is this is aforeclosure and I'm already getting this house cheap "as is." So trying to get this one fixed as cheaply as possible.
Where are you located?
So far as I know, sand doesn't expand when wet, although maybe there are/were hydro-stolic(sp?) pressure issues?
With my mouth I will give great thanks to the Lord; I will praise Him in the midst of the throng. For He stands at the right hand of the needy, to save them from those who would condemn them to death.
- Psalms 109:30-31
It's in Northeastern Anoka county north of the Twin Cities. It's a former bed of the Mississippi river and 100% sand down to 60 feet. My guess is the soil got saturated in late fall and then froze.
>>My guess is the soil got saturated in late fall and then froze.That can also be a source of movement in a block wall.In my area, it is rarely seen much more than a course or two below grade.How deep is your frost line there?BTW, there are a lot of bowed walls in my area: I beams, properly anchored top and bottom are the most common reinforcement.A new approach from a couple of companies is to fix some space age, strong and unstretchable fabric to the insie wall to prevent bowing.I've seen a few installations, but not enough to form any conclusions.I am a bit skeptical (The system is only as god as the strength of the connection - I wonder what will prevent the face of the block from "spalling?")
With my mouth I will give great thanks to the Lord; I will praise Him in the midst of the throng. For He stands at the right hand of the needy, to save them from those who would condemn them to death.
- Psalms 109:30-31
Hi rjw
Frost line here can go to 48" or deeper depending on snow cover. I'm looking into the I beam "solution." I have a good friend who can get a backhoe cheap, or free, so I'm leaning towards the excavation route. Do you know what the specs are on the I beam approach? How far out of plumb is too far for I beams?
Look up that article on JLCONLINE.COM then under research.Cost $3.95 IIRC..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Thanks Bill,
I found one that shows how to pull a 3" bulge out of a block wall using plates and threaded rod.
Looks like its worth a try before redo the entire wall.
>>pull a 3" bulge out of a block wall using plates and threaded rod.That won't move the wall unless the exterior is excavated. Low cost, low quality approach, IMO.One such system used around here includes re-tensioning yearly, and they leave a huge wrench for the home owner.
With my mouth I will give great thanks to the Lord; I will praise Him in the midst of the throng. For He stands at the right hand of the needy, to save them from those who would condemn them to death.
- Psalms 109:30-31
I suspect it depends on the nature of the soil. Peaty soil would probably be fairly easy to push back, eg. And pretty much any soil can be pushed back if you're willing to take several years to do it.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Thanks rjw,
My neighbor works for a paving company and he can trench for me cheaply. I agree, I can't see how this works without excavating. But with excavating and lifting weight off the block with jacks it should be doable. I'd rather avoid rebuilding the wall if possible.
Not knowing your soil and conditions, I'd be reluctant to spec.Common reinforcement around sometimes involves excavating, pushing the wall back into position, and adding steel. Other times just adding steel and (preferably) re-stressing it and/or grouting to fill the voids between the steel and the wall.I don't know exactly how I-beams are spec'd, and it is my understanding that ll sorts of factors go into calc'ing I-beams, so I defer to local experts on that issue, but "C-channel" is a common misapplication around here (per the experts) and poor attachment, especial at the floor joist end is also common.
With my mouth I will give great thanks to the Lord; I will praise Him in the midst of the throng. For He stands at the right hand of the needy, to save them from those who would condemn them to death.
- Psalms 109:30-31
River sediment can contain a lot of organic material, or can contain expansive clay. Both will cause problems. But being in MN, frost is also a problem, and it sounds like this area may have a lot of subsoil moisture, so frost pressure will be considerable.Look for signs of water seepage in the basement.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
hi DanH
USGS soil data call our soil "zimmerman" sand. I had a well drilled 10 years ago and the driller said nothing but sand down to 60 feet. Not even sandstone or glacial till. With no gutters, small overhang flat lot, my guess even sand can get saturated.
Yeah, if you end up digging down to the footing you'll want to put in tile, if there is none there already.However, tiling is required for homes built since about 1975 -- how old is this one?
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
1973. So who knows whats down there....
You can check with the local BI and see if tile would have been required then. (Of course, just because it was required doesn't mean it was there.)
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Thanks Dan will do.
Don't necessarily blame the (lack of) gutters. Expansive soil and/or frost combined with lack of reenforcement in the walls will cause this. Well-drained soil will prevent it, but sometimes the rain doesn't just fall on the roof.
Note that there are ways to "stabilize" the walls without needing to excavate. If you really want to straighten them, however, you'll probably need to do some digging (or else remove/replace the walls). This may also be a good time to install footing tile, if there's any evidence of moisture problems.
There are specialists in this field who may be able to do the job cheaper (and certainly faster) than you can -- check around.
So if you look at where the foundation meets the mudsill, has the foundation slipped inward and the structure has stayed in place?
Or (if the mudsill were properly attatched to the foundation) has the foundation drifted and displaced the structure on the opposing foundation wall?
I have seen that happen, and although it was correctable it was NOT pretty.
Go look at the interface of the structure where the foundation meets the mudsill on the wall opposite where you have detected this problem.
Do you actually know where the footing is relative to the foundation? It very well may be much lower than the basement floor, although this may or may not have much bearing on your particular situation.
Butresses may very well have been called for in this situation, and that depends on soil conditions and general topography in the vicinity of the problem area.
Best wishes,
Eric
[email protected]
JLC had two articles on this about 3-4 years ago. One using I-beam butress and the other anchors into the ground.The article using ibeams mentioned a maximum bow that you can have in block wall and still be able to restrain it. This one sounds like it might be over that limited, but to be honest I don't remember the numbers.A friend of mine has a poured foundation that has about 8" where it cracked in the middle. But poured is much different..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Years ago I had a job with similar conditions, 46'-0" of 8" block. This was a full basement with mostly sand for the entire depth. We hand dug the outside to the top of the footing. Shored the floor and then removed the block. Poured reinforced concrete wall ,12" thick and 6'-0" high. then two courses of block and the third course is a bond beam.New anchor bolts installed into sill and bondbeam.
The cause of the original failure was probably 8" block below grade without reinforcement or filling the cells, and incomplete landscaping that caused rainfall to flow towards the foundation wall. I had an engineer advise me , best $500.00 I spent.The original contractor paid the entire cost, suprisingly without hesitation.This was a new custom home.
mike
Many years ago when I built my first home I laid almost 2000 10 inch blocks and I remember (or at least I think I do) That straight walls over a certain length needed pillasters or knee walls regardless whether they were below or above the ground. My rear basement wall was not as long as yours but I put in 2 knee walls about 5 feet high.
If it was mine, I would dig out behind the wall, put up a temp stud wall adjacent to the block wall then I would anchor into the floor some lumber and try to push the wall verticle then put up a couple of knee walls to hold it in place. Then if I was so inclined I would go outside and break into some of the top blocks(pieces) and pour very soupy mix concrete then patch the broken blocks.
Where I used to live most of the houses built before say 1985 were all block basements and they all cracked somewhere and none ever caved in that I was aware of.
roger
Thanks Roger. I found this article that uses griptite wall anchors to pull the block back into plumb. Which consists of two plates that go through the block connected via 3/4" threaded rod and the other plate is buried under the soil below frost depth. Then tighten the rod and pull the block plumb. Your suggestion is where I was headed. I think if I lift up the house, or at least take some of the load off of it and excavate outside, I have a good chance of pulling this into line.
I think you got it. I'd rather push the wall than pull it because at least from the inside youhave a firm stable base to push from. I'd still put in knee walls but if you go with plates you can stud that wall to cover the plates.
roger
There are some of the rod and plate systems that don't require excavation. The outside plate is driven down, and has some sort of funnel so that the rod doesn't have to hit it exactly dead center.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Another thing to keep in mind: It's county fair season here in the Northland. Good place to go to find all sorts of specialty outfits. If there's one in your neighborhood in the next few weeks, breeze through (during the day when the crowds are low is best) and check out the home improvement/maintenance exhibits. You might find a vendor that can do the job.