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  • el jefe
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house structural engineering questions
hopefully someone here is a structural engineer or knows one or at least knows something about the topic.

my parents' house is having issues with the load - bearing basement walls.  the wall has a protruding (convex) corner, which supports one of the main I-beams supporting the entire house.  the corner is bowing inward and cracked.  obviously, this is really serious and needs to be dealt with asap.

based on some googling, foundation wall anchors seem like a reasonable and cost-effective solution.  but here are the structural engineer questions...

1) will foundation anchors be good enough, given that the portion of wall in question is not just a foundation wall, but in particular supports a major I-beam?

2) my dad (who's being a little irrational, imo) is worried that if he has an engineer come and look at the house, he might condemn it on the spot (based only on this one, apparently fixable foundation problem?).  is this a realistic concern?

any help is appreciated.  my parents have very little retirement savings but they do have this house.  their retirement plan is to sell the house, move into something much smaller, and live off the proceeds.
  • Last Edit: February 23, 2017, 08:07:10 AM by el jefe

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Re: house structural engineering questions
Reply #1
Dunno how likely it is to be condemned, but procrastinating based on that fear is the worst thing he can do.  It's obviously going to have to be fixed before they can sell it.

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Re: house structural engineering questions
Reply #2
Dunno how likely it is to be condemned, but procrastinating based on that fear is the worst thing he can do.  It's obviously going to have to be fixed before they can sell it.
right, that is exactly what I told him

  • el jefe
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Re: house structural engineering questions
Reply #3
I just had an idea and called him to tell him to do it:  go buy and install some jack posts under the I-beam and maybe some of the rafters.  that should stabilize it while he thinks through a permanent solution and scrapes together money for it (both of which could take months).

jack posts are not that expensive, and (looking at some numbers) 5 or 10 of them should easily do the trick.

we are both aware that simply jacking up the posts until they bear the entire load could have disastrous unintended consequences (e.g., the sagging wall might only be held together by the I-beam ' s weight, in which case relieving the pressure would cause the wall to collapse).  the plan is to only tighten them until they begin to pick up *some* of the load and then leave them in place.  hopefully, that will pause the sagging.  but, if not, then the jack posts will simply hold more and more of the weight over time.  assuming they can handle the load (and 5-10 of them should be enough for that...), this seems likely to stabilize the situation, and unlikely to make anything worse.

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Re: house structural engineering questions
Reply #4
Jack Posts are a "temporary" fix that may last a long time.  I would buy the largest spread foot, especially near your subsiding wall since it may be the foundation that is failing in that area.

  • el jefe
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Re: house structural engineering questions
Reply #5
thanks.  yeah, I didn't think of jacks as permanent.

we *think* the foundation itself is ok.  the walls along that whole side are generally bowing inward, slightly but definitely, due to sideways pressure from the dirt outside + water damage to the cinderblock.  I think the causality starts with that, but as the wall is getting less straight and vertical, the weight of the house is accelerating its collapse.  the bowing and cracking is worst at the point where the I-beam is supported.

the whole wall needs to be fixed.  possibly a complete rebuild is necessary.  that will be expensive as fuck (though not fixing it will drop the sale price by at least as much, and probably even prevent sale...).  even something like anchors, while cost-effective up front, probably look sketchy as hell to prospective buyers.

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Re: house structural engineering questions
Reply #6
Both my parents houses (wood frame, one built in 1980, the other in 1989) had I-Beam floor supports that were basically 3" square posts with a screw level that the builder used to level the floor AFTER building the full house frame (before dry wall to avoid cracking).  One finished basement just covered these posts with a square floor-to-ceiling column frame covered in dry wall.  I found it surprising that these 1-1/2" threaded screws were "holding the house up".

The reason I say that these can become permanent is that they serve the exact same purpose as the original wall support.  As long as they are anchored and set on stable ground they provide the same or superior structure to the I-Beam as your wall support did. 

It will also cost far less to install a single support column/structure at or near the failed wall, and then rebuild the wall to only handle the house-edge load (floor joists ending on the wall) instead of building it back to original structure for supporting the I-Beam too.

I'm not a structural engineer and there are probably other ideas.  Ping RAFH for some advanced knowledge and advice too.
  • Last Edit: February 23, 2017, 09:48:53 AM by MikeS

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Re: house structural engineering questions
Reply #7
They should probably see if insurance will cover the repairs. It can be repaired, for sure, but whether it's worth whatever it might cost, I dunno.

Our basement in KS had some walls that were slightly bowed, but the county inspector signed off on them as being ok. We only had to have a moisture control system installed later. The anchor systems work well, but they aren't cheap, and are usually good for 50+years, but may occasionally need to be 'tightened'. It also depends on the internals of the walls. If they are only concrete, it won't take anchors as well, because it tends to crack, but if it's reinforced with rebar, it would be ok. The anchors will usually cause minor cracking though, and that comes with the potential for additional water leaks in a basement.


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Re: house structural engineering questions
Reply #8
hopefully someone here is a structural engineer or knows one or at least knows something about the topic.

my parents' house is having issues with the load - bearing basement walls.  the wall has a protruding (convex) corner, which supports one of the main I-beams supporting the entire house.  the corner is bowing inward and cracked.  obviously, this is really serious and needs to be dealt with asap.

based on some googling, foundation wall anchors seem like a reasonable and cost-effective solution.  but here are the structural engineer questions...

1) will foundation anchors be good enough, given that the portion of wall in question is not just a foundation wall, but in particular supports a major I-beam?

2) my dad (who's being a little irrational, imo) is worried that if he has an engineer come and look at the house, he might condemn it on the spot (based only on this one, apparently fixable foundation problem?).  is this a realistic concern?

any help is appreciated.  my parents have very little retirement savings but they do have this house.  their retirement plan is to sell the house, move into something much smaller, and live off the proceeds.

First off, a better description of the situation would help immensely, especially if accompanied by photos, the more the better.

What it sounds like is you have a floor girder bearing on a pilaster, a column built into the wall. That this pilaster is bending and cracking is not good. That it is bending & cracking separately from the wall means it's not acting with the wall, very not good.
So, what is the wall made of?
What is this pilaster made of?
How tall is the wall?
How thick is the wall?
Dimensions of the pilaster?
How much floor does this girder support?
How much roof? Floors above?
What do the wall & pilaster bear on?
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  • el jefe
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Re: house structural engineering questions
Reply #9
I asked my dad to take a picture.  here's a quick diagram, for now.

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Re: house structural engineering questions
Reply #10
hopefully someone here is a structural engineer or knows one or at least knows something about the topic.

my parents' house is having issues with the load - bearing basement walls.  the wall has a protruding (convex) corner, which supports one of the main I-beams supporting the entire house.  the corner is bowing inward and cracked.  obviously, this is really serious and needs to be dealt with asap.

based on some googling, foundation wall anchors seem like a reasonable and cost-effective solution.  but here are the structural engineer questions...

1) will foundation anchors be good enough, given that the portion of wall in question is not just a foundation wall, but in particular supports a major I-beam?

2) my dad (who's being a little irrational, imo) is worried that if he has an engineer come and look at the house, he might condemn it on the spot (based only on this one, apparently fixable foundation problem?).  is this a realistic concern?

any help is appreciated.  my parents have very little retirement savings but they do have this house.  their retirement plan is to sell the house, move into something much smaller, and live off the proceeds.

First off, a better description of the situation would help immensely, especially if accompanied by photos, the more the better.

What it sounds like is you have a floor girder bearing on a pilaster, a column built into the wall.
girder, yes.  not sure what it's bearing on meets the definition of a pilaster.  it is bearing on a corner of a cinder block wall.
That this pilaster is bending and cracking is not good. That it is bending & cracking separately from the wall means it's not acting with the wall, very not good.
So, what is the wall made of?
cinder block
What is this pilaster made of?
cinder block
How tall is the wall?
7 feet?
How thick is the wall?
cinder block thickness
Dimensions of the pilaster?
(see diagram).  the short section of wall is maybe 5 feet long?
How much floor does this girder support?
don't know.  wanna say it is not the main one for the house.  I think it T's off the main and extends 10 feet or so and then its end is supported on the wall.
How much roof? Floors above?
there are two floors above.  the top one has roof on it?
What do the wall & pilaster bear on?
i *think* the cinder block wall just sits on the edge of the foundation, which is just a big flat slab of concrete.

afaik, foundation itself is in good shape.  no major cracks or anything.  and it's been there >50 years, so it's had time to settle.

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Re: house structural engineering questions
Reply #11
If an engineer is going to condemn it on the spot he wouldn't be able to sell it anyway.  I'd get a professional involved asap.

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Re: house structural engineering questions
Reply #12
a few misc. things...

the picture probably won't come until tomorrow.  I am not on-site, so I can't just go and look at it.

incidentally, water has been seeping under the entire length of the wall for years.  the entire basement gets flooded once or twice every year.  sump pump and evaporation take care of it relatively quickly, but it does keep happening.

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Re: house structural engineering questions
Reply #13
So also years of water seepage...

I would keep quiet about the foundation problems. This is where well-planned arson & collecting on insurance money is a much more financial viable solution to the problem. Then sell the lot. Your parents would probably enjoy a new home in an active 55 community.
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Re: house structural engineering questions
Reply #14
ok, here are some pictures.  apologies in advance for the image quality.  dad is not a photographer.






these next two are below the girder, on the short section of wall










hopefully all that gives you an idea of both the overall structure and of the damage

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Re: house structural engineering questions
Reply #15
ok, here are some pictures.  apologies in advance for the image quality.  dad is not a photographer.






these next two are below the girder, on the short section of wall










hopefully all that gives you an idea of both the overall structure and of the damage
Yeah it does. Thanks.

I see two possibilities here, not necessarily exclusive. 1 - the "column", which in effect is the corner, is suffering from long term water damage which probably has caused the vertical rebar in the corner (there should be some) to rust and deteriorate, the rust being bigger dimensionally than steel, it expands and cracks to concrete block. This is what the pictures #4 & #5 sort of look like but they are missing the telltale rust stains draining out the bottom of the cracking. On the other hand, it sort of looks like someone painted the wall fairly recently and may have covered those stains us. 2 - The offset wall is breaking from the wall to the front (and may be doing the same to the rearward wall), likely very long term settling.

Probably not going to fail anytime soon, but you never know. At least without a complete set of structural plans, etc. Even then, hard to chase it all down and the best you'd get as an estimate is likely it's probably not going to fall down anytime soon. But it will deteriorate and it will eventually fail. Me? I'd fix it. Not that hard to do but messy.

So, what to do? Probably the best thing would be to install some temporary supports under the steel beam (just some 4x4s or even 2x4s if you use enough of them and cross brace them) and remove the offending corner back a whole block (about 16") in either direction from the corner, being careful to keep the existing horizontal rebar. That should be at least #4 horizontal at 16" oc (every two courses), remaining rebar to be cleaned of all rust and I'd suggest painting it with a zinc rich paint. Then either form a new concrete corner or install new block to replace what you removed.

Downside to above is no way to waterproof the new corner. Not unless one digs down on the outside a whole big enough for someone to apply the waterproofing. There are some surface treatments that claim to work with the water coming from the back but I am not entirely convinced by them. Please note with the second solution to get the last block or two in place (the others can simply be lifted over the corner rebar

This wouldn't cost much in materials, but the labor may be substantial. My guess is two days with two people. They could probably put up the temp scaffolding in a couple of hours and then spend the rest of the day removing the existing concrete block and either setting up the new concrete pour or installing cleaning up the rebar and prepping for which repair. Next day, probably a half day at most, mix and pour concrete, either as the corner itself or as the grout fill for the new block. Make sure you use the correct concrete for the situation. I'd suggest using a standard grout mix with 3/8" pea gravel.

That's about it.

I definitely would not attempt a cosmetic fix. It's not going to work except for a very short time.
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Re: house structural engineering questions
Reply #16
Thought: if you do the poured concrete corner, would it be possible to use a waterproofing additive in the concrete?
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Re: house structural engineering questions
Reply #17
RAFH - thank you very much.  i will pass this along.

a few follow-up questions...

1) am i right in thinking you're an architect?
2) is my dad right to worry that an engineer, on seeing this structural damage, might condemn the house on the spot?  (does that worry even make legal or bureaucratic sense?)
3) supposing we can't get to it soon, does it make sense to put up a few jack posts as i discussed before?  would it help?  could it hurt?
4) if he ends up hiring people to do the fix you describe, could the cost conceivably run into 5 figures, or would it easily stay in 4?