Basement wall reinforcing

[ztengguy]

Did a inspection of a home yesterday, and the walls of the basement were bowing inwards. to remedy, they had put in some small W column/beams as reinforcing. From the slab to the joists. They didn't put them in strong axis as you would expect, also didn't make them composite with the wall, just bolted to the floor, and then wedged in to the first joist, or in-between where they were perpendicular to the wall.

They seem to be doing something, they have deflected out with teh wall, so there is pressure on them. (I figure they were plumb or at least straight when installed.)

I a not sure how to describe what they are doing. Yea, they are taking some load, but how much?

Anyone ever design something like this, and what was your reasoning/assumptions behind it?

 

[a2mfk]

Sounds like a non-engineered repair at best

I wouldn't waste any time trying to figure out the what and the why of that, but figure out why the wall is bowing in the first place (poor original design, water table, expansive soils, all of the above). Then come up with a reasonable engineering solution based on why the wall is deflecting.

 

[ztengguy]

Yea, I doubt it was engineered. Im pretty sure there isnt any drainage around the house, nothing coming into the sump pump. my money is on water table/unreinforced design. I haven't been asked to fix yet, just to see if they were adequate.

 

[a2mfk]

Well if that is what you were asked to do, I think your job is very easy

 

[ztengguy]

Yes, but I know they are going to say 'Well they have been there for 20 years, why hasn't it fallen down??'

 

[MiketheEngineer]

Mother earth is a bitch and she will ALWAYS win. If you don remedy the root cause(s) as mentioned, they will continue to move the walls and eventually collapse them.

 

[a2mfk]

Then why did they ask you for your opinion?

You know how many structures I have seen where either the original construction or the modification were such abortions that I was surprised they had stood up this long? And I am have not been doing this THAT long and I am sure we have all seen lots of similar examples. The general public has not, its not their job either.

We all have our own style and way of handling these situations, I usually make a joke and then give them some technical explanation. If they seem uninterested or unwilling to go along then you just have to hand them a bill for your time and bid them adieu...

Oh, and you can always tell them that concrete walls will deflect, that is, until they fail. And that such a failure is unpredictable with the amount of information you have. If its unreinforced it could make a lot of noise and happen suddenly. Maybe the steel beam/column braces will hold, maybe they won't. Too many unknowns. It is their dice if they want to roll them. If it in your opinion represents a safety hazard then you should express this in writing to the homeowner and the building department.

 

[MiketheEngineer]

Forgot to mention that this is a rather common method of repair - also probably the ugliest and cheapest. But if you don't get rid of the water or plastic clays - it will never hold.

Typical is to dig along the outside of the wall to footing. Install drains and pumps - either inside to outside. Install heli-coil anchors or concrete deadmen and "pull" the wall back out somewhat. Back fill with 3/4'' to 1'' rock to within about 6'' of surface. Install dirt and grass.

This method usually gets rid of the water, clays etc and re-aligns the wall somewhat. Be careful if you have a brick veneer. Also, don't pull the wall out too far!!

 

[a2mfk]

That sounds like a good idea Mike. The homeowner will love that!

Lots of times they just want us to tell them everything is fine so they can sleep better at night, even if we lie to them they'd prefer it...