Hi, My poured basement walls on my house are pushing in and cracking because they backfilled with clay. Cracks are small, but one wall is pushed in 2.5 inches from plum and its getting worse. No water in the basement and the sumppump runs fine. If I only dig down 4-6ft by hand instead of going all the way to the footer - 9ft would that relieve the pressure from the clay? I'm trying to do this a cheap as possible. I can probably pull off going down 4-6ft by hand, 9ft is gona cost some big **. I plan on using 1-5 foam, plastic and backfilling with peagravel(clearstone). Your thougts on if 4-6ft is enough. Thanks in advance.

It's sure taking a chance. My brother alsways used to ask, "Why is there never time (or money) to do it right, but always time (or money) to do it over again?"

I saw no mention of a dampproofing coating, and I'm not sure what "1-5 foam" means. Read through LicensedWaterproffR's posts in this forum and you'll learn what is required.

Well the poured walls are only 7.5ft tall. Remember that I'm trying to do this as cheap as possible. Can I get the pressure off the wall by only digging down 4 or 5 ft? Has anyone heard of this working? I plan on putting on 1.5 inch foam down 4ft and patching the small cracks and plastic behind the foam to water proof to the level I dig too and then back filling with pea gravel. I've been digging and the clay is wet and very heavy. I was thinking about post hole digging a couple of spots to the footer to let the water drain?? Your thoughts? - thanks in advance.

My thoughts are that the proper way to waterproof a basement wall and relieve pressure on it is well-known and fully described many times in this forum, and if one hopes to actually solve problems, one ought to do it the right way and all the way, not half-way.

Ok your suggesting digging to the footer correct? Being an Architect isn't 90% of the force coming from the top 2/3s of the soil? Give it some thought and please reply. I appreciate your help.

wiscdave -

You are wrong about the load on the wall. Acording one accepted method of analysis, the load on the botom 1/3 is about 25% higher than the total load on the upper 2/3. The pressure on the wall (that may cause leakage)are many times more.

Replacing the clay behind the wall with clean granular material (about 2-3 wide will reduce the load. Getting rid of the water behind the wall will reduce the pressure also.

You did not say what the direction of the crack is, but i imagine it is horizontal or diagonal. Since it is a poured wall, some minor vertical shrinkage cracks are common.

Since the wall is cracked it is not as strong as it was when built and you can expect more movement unless a proper correction is made to the soil backfill.

When you go to sell, you can expect this to be caught, but any decrease in value can be minimized if you have a professional sign off on the repairs. Buyers don't take to well to individual contractor "guarantees" when they are in the drivers seat.

Thanks concretemasonry. Can I ask where you get your detail for the anlysis? The load pushing in from the bottom making the lean inward is hard to digest but believable. What a PIA it is to dig this thing out is all I have to say.

I calculated the numbers on the loads based on an a soils engineering class I took. the same concept is used in many structural foundation wall designs. - It is generally referred to as the "equivalent fluid pressure method". It gives reasonably good results for silty and wet clay soils.

There also more complicated methods, that will give somewaht different numbers, but all come up with the same conclusion that the pressure increases with the depth.

Drain tiles will obviously improve the situation, because some of the water is removed.

If I had to guess, the wall with the movement is parallel to the floor joists and there is not enough blocking between the first few joists and possibly not enough anchor bolts. - Just a guess. If not, it is a long wall and/or possibly where the construction excavation ramp was.

When you get done, make sure you do everything possible to get the water away from your house and make sure your downspout extensions are well beyond the construction excavation limits (as much as 10').

Like Richard, I question what the foam would do to solve your wall movement problem.

The foam would insulate and give the wall some relief if the pressure did come back from pressure on the side.

The foam is a short term bandage for a bad wall and backfill. The soil will exert the same pressure, compressing the foam and moving the wall. Foam does not spring back.

The foam will add R value that was not there before. I will backfill with Gravel.

My outstanding question is still: Will only 2 feet of clay at the bottom of a 7.5 ft wall put enough pressure on it to continue to push the wall in if the above 5.5 ft is gravel? I might even put in I beams to re-enforce the wall from moving any more. That bottom 2 - 2.5ft is the hardest to dig by hand.

You will still have clay in the bottom two feet and that can stop the moisture from getting to the tile, so the water will still be there. If you backfill with clean stone, that will help, but remember you are trying to resist the horizontal load from the wet clay. Even the clean rock and water add (less but still some) to the load on the wall. I doubt you will be willing to dig wide enough to really help enough, considering that your wall is now weaker than it was before it cracked and moved. - It is just a matter of time since it is still moving.

Since you obviously want to do a DIY job, why not get a professional to give you some options, so you can consider what you are willing to tackle. - It may save you a lot of work doing something that will not help. Steel beams installed improperly or at the wrong place will be costly and do no good.

Just out of curiosity - what is happening to the house above or is it not attached very well to the poured foundation that has moved 2 1/2"?

The house is not taking it well, it is creaking and has pulled away from the outside boards by the 2.5 inches. I was thinking about post hole digging some holes to the tile every couple of feet to give the water somewhere to go (tile) going down maybe?? I have some quotes that were just too much to handle and they explained to me that they would dig all the way to the tile etc. I have a friend with a dumptruck and skidsteer to get rid of the clay and dump in the clean stone, but the digging out part puts me out of budget for this year.

Do I have to go all the way to the footer everywhere. How would you keep the wall from moving now that I dug down?

If walls are not cracked, bowed or leaking, it isn't necessary to dig them out at all. But where the bowing has occurred is where the digging, repairing, waterproofing and backfill with gravel must be done, and there is no half-way method of doing it right. After the wall is repaired and the hydrostatic pressure relieved, if the bowed wall is parallel to the floor joists as "concretemasonry" suspects, then the top of the wall should be braced to the floor joists with rows of solid bridging extending in a few joists and placed no more than 8 feet on centers. Hopefully that will help to stop further bowing.

Concretemasonry makes another good point about having a licensed professional sign off on repairs, to help if you have to sell the house. But, in order to have someone do that, they must monitor the remedial work as it is done. I don't know about others, but just telling me what you did wouldn't be good enough; I would have to have seen it happen.

After reading your initial post more closely, I notice you said the walls (plural and more than one) are pushing in and cracking. You decribed the worst, but what about the others? - Same height, same thickness and same soil.

Your drain tile may have saved you from a collapse if that was responsible for keeping the water away from the walls where the hydrostatic pressure could build up.

You really have someone (a professional) take a hard look at the basement before you spend a some money and a lot of sweat on doing what may possibly be the wrong repair. Any wall that has moved 2.5" will never have as much strength as before it cracked and then moved. - Just my $.02 worth. The professional opinion could be a good investment.

Ok, thanks guys. We're going to dig all walls affected down to the tile, straighten and back fill with pea gravel.

You might consider using a helical pier tie-back in some key locations to help resist the clay forces. They will push on the pea gravel also if complete water control is not achieved. Just a little insurance for that much work.

helical pier tie-back : never thought of those, how often should they be placed and what is the cost per each and can they be installed by me?

IS $40 per hour for 1 machine exgavator digging out basement - is that a good quote