# digging beside a "superior" wall



## realolman (Mar 20, 2012)

My basement is constructed of the precast "superior" walls. I bought the house about 7 years old, and I have no complaints with it, but one time I had water coming in around the sewer drain, which was about a foot off the basement floor. 

From the inside, I enlarged the hole through which the sewer went through, so I could get a good layer of hydraulic cement in there. The wall was backfilled with small gravel, a* large* quantity of which came in through the hole I just enlarged.

. The walls do not sit on a concrete footer, but a bed of gravel. Now my question...*I want to dig right beside the foundation How do I keep the gravel from running out from under the wall*. 

I questioned and was contacted by a rep from Superior walls, but he didn't really have a good answer... kind of a you'll just have to play it by ear, and figure it out. He wasn't smart or flippant about it.... just seemed that there wasn't a good answer. 

I hope you folks may have a better answer... thanks.


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## Just Bill (Dec 21, 2008)

If I understand correctly, you have a leak where the sewer pipe goes thru the wall??? If yes, just inject some expanding urethane foam into the opening. It will fill the hole and seal it up.


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## realolman (Mar 20, 2012)

I guess you were reading in English, and I was writing in dumbbell :wink:.

Thanks for your reply, though.

I discovered how small the gravel was that my foundation is backfilled with ( and I assume sitting on ) when I enlarged the hole for my sewer pipe. A large quantity of it ran back into the basement... much more than I would have expected.

Now, I want to dig beside and below the basement wall for a retaining wall, but I am afraid too much gravel will run out from under the basement wall... I wondered if anyone had any suggestions how to keep it under the Superior wall, or if I just dug beside it and let it run, if enough would run out to cause a problem. the hole for the retaining wall will be about 3' wide, and near the corner of the basement.

The Superior walls do not sit on a concrete footer, but a bed of gravel.


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## Ravenworks (Oct 31, 2010)

The gravel it there to serve two purposes
1) it is there for a drainage 
2) it is there to help relieve hydraulic pressure
The problem you have created now is a void on the other side of the wall,when you build your wall you'll need to have _*GOOD Drainage*_ incorporated into it or the water will migrate.


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## realolman (Mar 20, 2012)

I guess I shouldn't have mentioned the sewer.

What I want to do is dig a 3' wide hole beside and below an existing "superior wall". Yhe superior wall sits on a bed of gravel. I am afraid if I dig beside it the gravel will run out from under the superior wall causing some sort of failure.

Can you think of a way I can prevent the gravel from running out from under the superior wall if I dig beside it deeper than it is, or do you think not enough gravel will run out to worry about?


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## Ravenworks (Oct 31, 2010)

realolman said:


> I guess I shouldn't have mentioned the sewer.
> Can you think of a way I can prevent the gravel from running out from under the superior wall if I dig beside it deeper than it is, or do you think not enough gravel will run out to worry about?


You may be able to pump some grout into the gravel in that area to help contain it?

I would worry about gravel loss if it were me because it is system the relies upon each other,IE wall holds gravel in,dirt hold gravel in gavel hold wall up.You lose one you risk losing the other. 
As for the company you called,they are not going to advise you when it could make them liable.
I feel for you,but I know that you don't want to lose the footing


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## realolman (Mar 20, 2012)

Ravenworks said:


> You may be able to pump some grout into the gravel in that area to help contain it?
> 
> I would worry about gravel loss if it were me because it is system the relies upon each other,IE wall holds gravel in,dirt hold gravel in gavel hold wall up.You lose one you risk losing the other.
> As for the company you called,they are not going to advise you when it could make them liable.
> I feel for you,but I know that you don't want to lose the footing


thanks... You understand.

I thought about trying to get some runny cement ( grout ) into the gravel . I also thought about trying to drive something a bunch of stakes or maybe a bunch of flat steel stakes 2" X 1/4" ...or something like that along the wall .

Nothing seems to really trip my trigger as being a "yeah that'd probably work" idea.

So no one ever builds onto a building with a superior wall?


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## Ravenworks (Oct 31, 2010)

realolman said:


> thanks... You understand.
> 
> I thought about trying to get some runny cement ( grout ) into the gravel . I also thought about trying to drive something a bunch of stakes or maybe a bunch of flat steel stakes 2" X 1/4" ...or something like that along the wall .
> 
> ...


Yes all the time,this is not typically a DIY ,I would imagine they would use a grout pump and inject the area that is to be worked on to stabilise it. If you don't you run the risk of failure. I would call a slab jacking company they have grout pumps and encounter stuff like this.What ever method you employ it better be fool proof.


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## concretemasonry (Oct 10, 2006)

The gravel is a required item under the approvals for wall you described. I if it is a "Superior" wall system, it relies heavily on the gravel under the wall system and you cannot dig too close to it or under it. There is a prescribed width of gravel required because of the lack of a concrete foundation.

It is not a continuous wall structurally (such as poured concrete or block laid in running bond, but separated walls sitting on a gravel base, so that why the support is required in case the minimal ties are not enough for vertical continuity. They is probably why you did not get an approval or an semblance of a guarantee from the installer or manufacturer.

Dick


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## Daniel Holzman (Mar 10, 2009)

You have entered the twilight zone here, because any digging which allows the foundation gravel to shift is almost certainly going to void your warranty, which as I am sure you are painfully aware is a very big deal. Since Superior Wall clearly does not want to accept responsibility for foundation failure, and their product is not intended to have holes dug adjacent to it, they quite responsibly are refusing to tell you how to dig.

This is essentially an underpinning job. In my experience, you only undertake a job requiring underpinning when you have a very good reason to do so, and no reasonable alternative. If you have to do it, you may need to drive sheet piles adjacent to the wall, grout in place (as noted by other posters), or use bracing with walers. None of this is simple or free, and it is almost a given that any such action will void your warranty. My suggestion is to closely examine your project, and see if you can move the digging operation outside the foundation support zone, as defined by Superior Wall. If you absolutely have to dig adjacent to the wall, you may want to hire a contractor willing to guarantee in writing, supported by a bond, that your wall will not settle or collapse. If you insist on doing this work yourself, make sure your homeowner's insurance is going to back you up in the event of trouble.


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## realolman (Mar 20, 2012)

Thanks for all your input. Unfortunately, I don't feel any closer to a solution.

The reason for the digging is to replace a failed retaining wall perpendicular to the existing superior wall. the wall goes immediately beside the entrance to the garage that is in the basement formed by the superior wall. 

Where the garage doors are, would they not have had to pour some sort of footer below the frost line? The walls would be pretty much sitting at finished grade, if not.

The retaining wall has to butt up to the superior wall. I don't see any alternative to just digging it out and taking my chances and hoping that the gravel doesn't run out enough to cause a problem. if it runs out, pour concrete in the void.... I don't see any alternative. I could probably try some sort of retaining wall that did not go below the frost line, but I don't see much hope in that either. I'm already removing one failed retaining wall

Although I know it is too late... I see no reason why they don't put those stupid things on a concrete footer. The water could be drained out just as well as having it sit on the gravel bed. If it wasn't anchored, the wall could expand or contract ( or whatever it's supposed to do) just as well on a concrete footer. I like the idea of the wall, but I think putting it on that gravel bed is just dumb.


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## Ravenworks (Oct 31, 2010)

I agree whole heartedly with the two poster before me and suggest that you get the opinion of a competent person,such as an engineer.
In reality what you're dealing with is a house of cards,one wrong move and everything comes down.
I also want to retract what I told you about grouting the gravel,because grouting is only one part of a whole system involved in the modification.


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## EdinPA (May 9, 2011)

*Superior Walls of America comments*

realolman said:


> I guess I shouldn't have mentioned the sewer.
> 
> What I want to do is dig a 3' wide hole beside and below an existing "superior wall". The superior wall sits on a bed of gravel. I am afraid if I dig beside it the gravel will run out from under the superior wall causing some sort of failure.
> 
> ...


I work for Superior Walls of America. It is the company that licenses others to manufacture, install and sell the Superior Walls technology. 

First, let me say that the job you are trying to undertake needs to be reviewed by a person competent in applying the structural design principals involved. In many cases that will be a structural engineer. Some builders may also be able to help or advise you.

Second, Superior Walls licensees allow builders to place the foundations on concrete footings if they so desire but that is not the prefered method for a variety of reasons.

Third, The crushed stone footing, however, does indeed present you with a different structural situation than a standard concrete footing but it is not an impossible situation. You just need to take into account all the loads and do not violate the law of gravity. You never undermine any foundation without considering the loads and making sure that you provide those loads with support at all times. Please review our technical resources to see if there are any ideas contained therein that may help you. Here is a link. http://www.superiorwalls.com/tech_resources 

Specifically, I recommend that you take a look at our builder guideline booklet. Page 11 and page 12 illustrate a couple of situations where a wall may span a distance of 5' without support, but remember you still always need to adequately support the loads and make sure those loads are adequately transmitted to the supporting soil. When our factories originally design your walls they provide you with a foundation that will support all the anticipated loads as indicated on the design drawings for the project. The crushed stone footing provides you with superior drainage if installed according to our guidelines.

The best advice that has been provided to you so far was stated below by Daniel Holzman - he said


> My suggestion is to closely examine your project, and see if you can move the digging operation outside the foundation support zone, as defined by Superior Wall. If you absolutely have to dig adjacent to the wall, you may want to hire a contractor willing to guarantee in writing, supported by a bond, that your wall will not settle or collapse. If you insist on doing this work yourself, make sure your homeowner's insurance is going to back you up in the event of trouble.


Feel free to contact Superior Walls of America if you want to discuss your options with our technical staff. As indicated by a couple of the gentleman before, for liability reasons we cannot provide you with engineering support, but we would be happy to help you understand your options and discuss your situation with you.

www.superiorwalls.com or 1-800-452-9255


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## realolman (Mar 20, 2012)

EdinPA said:


> realolman said:
> 
> I work for Superior Walls of America. It is the company that licenses others to manufacture, install and sell the Superior Walls technology.
> 
> ...


I HAVE talked to someone from Superior walls. He did not have any specific advice, but more or less advised me that I would have to play it by ear to see if I could determine what needed to be done as I was doing the work. 

Frankly I am a bit offended by the condescending tone of your post. 

I never had any intention of "undermining" the wall, or "violating the law of gravity"... unfortunately, digging anywhere near it in a manner that would be acceptable with traditional construction, seems to pose an unusually high chance of THE SUPERIOR WALL UNDERMINING ITSELF, due to substitution of a concrete and rebar footing with a bed of gravel.

I need to dig a 3' wide ditch below the frost line up to the Superior wall , and I need have this reviewed by a structural engineer??? It would probably be less expensive to fix whatever damage may result.

I am at a loss to understand why the company that engineered the unusual situation that I am faced with at this point "_cannot provide you with engineering support_" .


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## Daniel Holzman (Mar 10, 2009)

OK realoman, back up and try to understand where Superior Wall is coming from. Their wall system is perfectly standard, it is DIFFERENT than a typical cast-in-place concrete wall. It is a precast wall that comes in segments, and is typically supported on gravel, which is less expensive than casting a concrete footer for the wall. That is why Superior Wall is in business, they offer a cost competitive solution for rapidly installing a wall, so I don't know why you are so pissed off at them for building a wall the way they always build walls. And by the way, I don't own stock in Superior Wall.

As to why they won't engineer your installation, well that is their business. They supply walls that are not intended to have excavations immediately next to them. If it were a cast in place concrete wall, you would have similar issues, if the footer were on gravel and you wanted to excavate below the footer.

As to not needing an engineer to look at it, of course it is your right to excavate immediately adjacent to your foundation and "take your chances". I do not recommend this approach, as failure could lead to serious or fatal consequences, but I also appreciate that you probably think it is ridiculous to hire an engineer for what you obviously think should be a simple job. If you don't care to pay the money for an engineer, make sure your insurance will cover self inflicted damage to the house, and make absolutely certain you have an escape plan in the event the trench you are working in collapses on you, or the wall falls over on you. And try to understand that Superior Wall is not in business to design your project, they certainly do not want liability for failure any more than a DIY chat room wants to assume liability for your project, so of course they are not going to help you engineer the job.


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## realolman (Mar 20, 2012)

Daniel Holzman said:


> OK realoman, back up and try to understand where Superior Wall is coming from. Their wall system is perfectly standard, it is DIFFERENT than a typical cast-in-place concrete wall. It is a precast wall that comes in segments, and is typically supported on gravel, which is less expensive than casting a concrete footer for the wall. That is why Superior Wall is in business, they offer a cost competitive solution for rapidly installing a wall, so I don't know why you are so pissed off at them for building a wall the way they always build walls. And by the way, I don't own stock in Superior Wall.
> 
> As to why they won't engineer your installation, well that is their business. They supply walls that are not intended to have excavations immediately next to them. If it were a cast in place concrete wall, you would have similar issues, if the footer were on gravel and you wanted to excavate below the footer.
> 
> As to not needing an engineer to look at it, of course it is your right to excavate immediately adjacent to your foundation and "take your chances". I do not recommend this approach, as failure could lead to serious or fatal consequences, but I also appreciate that you probably think it is ridiculous to hire an engineer for what you obviously think should be a simple job. If you don't care to pay the money for an engineer, make sure your insurance will cover self inflicted damage to the house, and make absolutely certain you have an escape plan in the event the trench you are working in collapses on you, or the wall falls over on you. And try to understand that Superior Wall is not in business to design your project, they certainly do not want liability for failure any more than a DIY chat room wants to assume liability for your project, so of course they are not going to help you engineer the job.


I am not pissed off at them for building a wall the way they always build walls. I am pissed off because the walls they build are so susceptible to failure by doing such a simple thing as dig a hole beside them, and they offer no assistance in trying to mitigate that susceptibility. .. which is far greater than the likelihood of a cast in place or a block wall on a cast footer. 

Why don't you try to understand it from where I'm coming from. I don't want them to engineer *my *project... I do think they should have some ideas about how to keep *their* engineering from failing during such a common practice as excavating beside it for something that could be as simple as a ditch for an electric service. Or in this case a 3 ' wide hole for a retaining wall. God forbid, anyone would want to add a whole *room *to his house.

I would _not_ have similar issues with a cast in place concrete wall or a block wall. I have dug completely under similar footers before with no consequences. Why would you spend the extra money to put gravel in a footer excavation in undisturbed ground into which you were pouring a concrete footer? 

It is my business what I do, and I intend to take my chances. If the thing is that flimsy that it falls apart by excavating a 3' hole next to it, well I just don't know... that's pretty pathetic.

You want to scare me into paying an engineer ( who will tell me what? ) with a bunch of talk about stuff collapsing on me... well, I don't think I need any "help" from you, because it doesn't seem to be very pertinent . I want to know how to keep the gravel under the Superior wall, or how much I can lose without the wall failing. You shoulda been a lawyer. Maybe if you were my lawyer, you'd say they should post some sort of nameplate on their walls and on theor website informing perspective buyers of the increased difficulty in adding onto the basement.

You can probably dig a hole beside your house. If your house was like this you'd understand. I'll figure it out.


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## Ravenworks (Oct 31, 2010)

To add to this thread,the next time you are at a big box store take a good look at the building,I have erected many pre-cast buildings and they are my least faviroite because they rely on many features to make them work. 
On a smaller building the sections weigh 10,000 lbs each some of the larger ones go as high as 40,000 lbs each I am here to testify that when things go bad they happen without warning and quickly.
I get your frustration but in order to accomplish this simple task please consult with someone,it may be as simple as driving a plate in the ground to hold things together until you finish your work.


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## realolman (Mar 20, 2012)

Ravenworks said:


> ......it may be as simple as driving a plate in the ground to hold things together until you finish your work.


So what's the big problem with saying that? 

Seems to me that Superior walls would have experience with this problem and what is the big liability issue with offering the results of their experience and expertise?

I don't want them to "engineer" anything concerning my project. They don't even have to know what it is. 

The question is: I have to dig a 3' hole beside your wall and below it. How do I keep the gravel from coming out from under your wall? Alternatively, how much can I safely lose from under it, if I replace it with concrete as soon as possible?


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## Ravenworks (Oct 31, 2010)

realolman said:


> So what's the big problem with saying that?


Because if something happens all a lawyer has to say it they told you to do it,yes it is that simple.
Sad world we live in.


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## realolman (Mar 20, 2012)

I don't think that is true. I think it is an excuse.


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## EdinPA (May 9, 2011)

*response to realolman*



> I HAVE talked to someone from Superior walls. He did not have any specific advice, but more or less advised me that I would have to play it by ear to see if I could determine what needed to be done as I was doing the work.
> 
> Frankly I am a bit offended by the condescending tone of your post.


Mr. realoman, again Daniel Holzman is the one who is giving you the best advice. 

Also, it is not my intention to speak to you in a condescending tone. Sorry, if my comments came across that way to you. As you know it is difficult to infer someone's tone from text alone. I am just presenting you with the facts as I know them with the hopes that you will make the best decision. 

The Superior Walls representative who you spoke with was most likely an employee of a local licensee. They are an independant business who is licensed to manufacture, sell and install Superior Walls panels. The phone number I provided you was directly to the corporate office.

Best of luck on your project.


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## Amazingglazier (Dec 27, 2011)

*Not to steal your thread!*

I have a friend of mine who owns 1 store in a small one story strip mall. He saw me across the street at my shop and had me "come right over " to see his latest project. He is so proud of it, I saw it and got the hell out quick! he had a very small basement under the back of his store maybe 8'x18', he wanted a full basement. He hired a few Home Depot workers and had the pull all the sand out in about 6 20 yard dumpsters and isn't done yet!!!!!????????? The building is about 18' wide x70' long, looked like 2x10 on 16" centers for the rafters, 16' cement block firewalls between the stores sitting on like24" wide x 24" deep footers down the length of the building. I live on Long Island , NY all sand! Am I wrong to have told him he is nuts with nothing to stop the 6' of sand under the footers from imploding with the weight of the firewalls on nothing but sand?? He thinks it is fine with about 8-10 4" x4"s holding his rafters up, sitting on top of 4" x4" laying in the sand. Told him about underpinning, but he's thinking about screwing plywood to the 4x4s and just pouring a slab. I'm thinking I'm not going in his building anymore, What do you guys think? He said he is going to consult the other Home Depot guy that does his cement!


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## realolman (Mar 20, 2012)

Coming back to post another, unrelated, question, I came across this old thread that I started many moons ago... some how back then I got the info I needed from Superior walls, and thought I would post it now ... this is the gist of it ... 

The Superior wall can span a certain distance unsupported... I don't remember what that distance is, but it was fairly far. I was surprised how far 

Gravel has a certain slump, so it's only going to run out so far. 

Assuming the slump of a pile of gravel was 45°, and the gravel was a foot thick... its only going to run out for one horizontal foot under the wall on each side of the excavation 

If the span of the excavation that causes the gravel to run out from under the wall plus the distance the gravel runs out does not exceed the distance the Superior wall can span unsupported, there should be no problem. 

In my case, it wasn't even close... plus I replaced it with concrete

....so I replaced a crappy looking , failed railroad tie retaining wall with a poured concrete retaining wall with a large cantilevered footer, rebar, and veneer stone. It has LOTS of drainage and I believe it will last much longer than I will ... it looks great and I am very proud to say that I did it myself


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