Search the forums

Loading

Foundation Footer

lysianne's picture

I started a new home constrution project and the contractor poured a footer the same day he discovered there was a cistern, which was removed, right at one of the walls.  After pouring, with rebar added and 12" deep, it still sunk significantly in that spot, maybe 3-4" and at least 5' long.  His solution is to transit the gap with a lentil (I think concrete block) mortared over the dip.  Will this hold?  Should I be worried the spot is weak and my wall might sag there?  Does the footer need something extra for reinforcement or was this an issue that should be resolved by starting over?


This is my first home project ever and I don't have anyone to advise me on whether to trust this contractor.  Any advice much appreciated.

If the lentil is a (post #210151, reply #1 of 33)

If the lentil is a steel-reenforced concrete beam, of sufficient size, then that should suffice.  If it was just "CMU" (individual "concrete blocks") then it's worthless.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Worthless engineering advice (post #210151, reply #4 of 33)

@Dan H-

You know virtually nothing about the structural conditions this poster's home foundation or soil conditions. The only thing "worthless" is your seat of the pants structural analysis of the situation.

I don't completely understand (post #210151, reply #2 of 33)

I don't completely understand your description of this footer that sank. However, any fresh concrete foundation part that immediately sinks 3-4 inches was placed on uncompacted ground and needs to be replaced or properly reinforced using a technique like mud-jacking. That your contractor doesn't redily acknowledge this is a big red flag. I'd dump this guy if I could. Even if you have to eat the cost of the work so far, you'll be better off without him. 

Thanks for your feedback.  i (post #210151, reply #5 of 33)

Thanks for your feedback.  i did a measure to be sure and it's 1.5 inches sunk in.  My understanding is the lentil is reinforced though I haven't confirmed that.  What is mud-jacking?

First it was 3-4" that it (post #210151, reply #8 of 33)

First it was 3-4" that it sank....now it's 1.5"---or less than half.  While any measurable amount of footing settelment during a footing pour is questionable, so is your sensationalizing of said event.

There should be zero (post #210151, reply #11 of 33)

There should be zero settlement of the footer. Any amount at this stage of construction spells trouble. I'll emphasize that: TROUBLE

You cannot solve this problem by consulting with any internet forum. You need a local consultant to guide you and act as a knowledgeable counter to the contractor's self proclaimed experience. I would suggest that you put a halt to this work now. The situation will tilt further south from your favor with the addition of any work by the contractor or his subs. You need to get a handle on the problem and solutions from an independent expert. I think you should hire a registered professional engineer who specializes in foundations. Yes, there is this speciality and that's the person you need. Don't hire another contractor, don't believe your brother in law, don't listen to the contractor's foreman, and don't take any guff from any of them. 

I'm not going to explain mud jacking because I don't know if that is an appropriate fix for your situation. Hire a local expert and listen to him/her. If the expert can't offer any recommendations, then you hired the wrong person. 

Did you or your contractor (post #210151, reply #3 of 33)

Did you or your contractor have the footings inspected before concrete was poured?

The inspection occurred on (post #210151, reply #6 of 33)

The inspection occurred on the additon, but before the garage footer was poured.  I put a call into the inspector to ask his optinion, but no response yet and the block layers are coming in on Monday... the reason why I decided to try and get some technical advice before I face the contractor on Modnay.

What kind of inspection occured? (post #210151, reply #7 of 33)

Inspections of footings generally require the bearing capacity of soils to be in the 2000 #/psf range. This means footings should be cast in non-expansive clay soils that are undisturbed or well consolidated.

If your footing was of typical width (20"+-) and of 12" depth and sank during the placement of wet concrete, then the footing base was apparently of inadequate bearing capacity which is required by code.  I say this because, according to my calculations) the weight of your wet concrete during the pour (approx 140# per cu.ft) would have  translated to a load of 244 # per linear foot, or 140 # per sq. ft. This is well shy of required bearing capacity range (even if you add in the negliable weight of rebar).

I'm really amazed that you (post #210151, reply #10 of 33)

I'm really amazed that you might even consider letting the contractor lay blocks on Monday. If your footer sank as soon as it was poured what do you think the future holds? Will the contractor come back in 5 years and redo the job when the footer sinks again? I know you want to get your house done but this is crazy. The fact that your "contracor" is willing to go ahead scares me. Hire your own structural engineering company to do calculations and soil test then go with their reccomendation. Do not let them lay blocks until you do.

Florida Licensed Building Contractor, 40 years experience in commercial remodeling, new homes, home remodeling and repairs and all types building maintenance.

How about that cistern? (post #210151, reply #9 of 33)

What was the size or volume of the removed cistern? What type of material was used to fill this void (removed cistern area) and in what manner was it placed?

Stop right now and do the job right... (post #210151, reply #12 of 33)

Stop the work right now, remove the work above the cistern, remove the uncompacted fill material in the cistern area, install compacted structural fill (compacted in 6" lifts or layers), cast new footings. 

Proceeding now will likely result in cracked masonry walls and continual settling.  Also, what about the garage floor or other slabs in the area? 

Compacting the upper portion of the exising fill is also not adequate, because you don't know what the material is that you are compacting...and compaction typically only works on the upper 4-6" of the fill profile....you need to get down to firm, undisturbed earth and build up from there...

Don't take any shortcuts....things like this never pay off..

Your contractor should have found this before pouring concrete - all of the contractors I work with 'rod' the ground below the footings - they drive a rebar into the soil to make sure there's resistance to the hammer blows.  He bears some of the responsibility here, but not all.  Assuming he didn't fill the cistern, had he notified you of its existance before the pour, you would have had to pay for the thing to be excavated and filled.  in my opinion, he is responsible to remove what is there and pour a new section at his cost and you're responsible for the excavation, fill and compaction. 

You should be concerned that the contractor is not doing the right thing....

No need to jump to erroneous conclusions (post #210151, reply #14 of 33)

@wmheinz-

Why do you assume the cistern was not removed and filled? The O.P. didn't mention either way.

I'm no expert on concrete.  (post #210151, reply #13 of 33)

I'm no expert on concrete.  But everything about this sounds totally wrong.  Just sticking a couple of pieces of rebar in a concrete footing doesn't make it capable of spanning 5'.

 

If it's sagging 1.5" now, how much more do you think it will sag after a house has sat on top of it for a few years?

OP did not give their (post #210151, reply #15 of 33)

OP did not give their location.

Here in WA sate, it is STATE LAW that any work involving a cistern or well that is abandoned or filled has it's own separate permit and inspetion and that it be filled with 6 sack min concrete or bentonite.

OP should check their state law on abandoned cisterns and wells.  The concrete guy could be liable for big fines if there are similar laws in your state.  CALL your state ecology department and pose the cistern aspect of the job to them. **

As far as the structural aspects, the 'concrete block" left me aghast along with others.

I surely hate permits, but these type weeinie contractors sure do show the need, too bad, rest of us have to pay the cost of their incompetence.

** note: if DIY, do NOT call <G>   but do comply with intent of the laws.

How do you know the footing (post #210151, reply #16 of 33)

How do you know the footing is not capable of spanning 5' and carrying the expected load? My guess is that as a self proclaimed non-expert on concrete, you don't.

BTW, the concrete sagged because it has plastic material properties when wet. What everyone is ignoring is the fact that the concrete has set-up (with rebar). It is probably acting, essentially, as a grade beam at this point. For all anyone knows this grade beam, or 'lentil', may be adequate. To simply advise putting another one on top (particularly without knowing knowing the facts) may proved to be unneccessary and redundant.

Why settle? (post #210151, reply #17 of 33)

Why would or should the owner settle for such a situation?  (pardon the pun)

You also are clearly not versed grade beam design.  "For anyone knows" about covers it.  Footings are not designed to be grade beams.  A grade beam would require the reinforcing to be tied together and be located primarily at the very bottom of the pour for its tensile qualities.  You now have no idea where the rebar in this footing is (or where it was at the time of the pour).  If it were placed in the middle, it may have migrated to be above the centerline making it useless as a grade beam or  If they were not careful during the pour, it could be anywhere in that footing  - surely no way to quantify its capacity as a beam. 

One could ignore the footing and design the wall above like it was any window or door opening and place a reinforced bond beam at the base of the wall.  This would act to support the wall above and you could actually hang the footing below it with additional reinforcement betweent the footing and the bondbeam.  Since the ground settled 1.5" or so with only 750 pounds of footing deadload, it's likely going to settle even further with time, leaving the footing suspended above the grade below - additional dead load for the bond beam above.  Certainly doable, but will require an engineered design solution. 

Also, what about the garage slab being poured over this area?  Are you also going to design a structural slab to span the space?  If not, it also is likely to settle over time. 

All of this should be done with the blessings of a Structural Engineer....and by the time he gets back to you. you pay his fee and provide the additioinal renforcing requried, the work could have been pulled out and redone correctly.

IMHO, the OP and the Contractor should do the smart thing and pull this out, excavate the fill material, place and compact new material and repour the footing...be done in a couple of days...

Cured concrete breaks; it (post #210151, reply #18 of 33)

Cured concrete breaks; it doesn't sag. 

I'll say it again (in other words) so that you can get beyond your shoe string engineering knowledge. The reason it sagged 1.5" at the time of the pour is because it was in a plastic material state and the footing had virtually no strucutural capacity. That doesn't mean it can't handle much more than the dead load of it's own weight  ( 1/2 ton or so) when cured. How much? Who knows. And who really cares because the OP doesn't give enough info to make an educated opinion on the best way to make the foundation structurally sound. Completely demo'ing what is there is not necessarily the best way...merely one way.

BTW,  a footing is essentially a grade beam. It acts as a beam and is set in grade. Footings are generally not designed to bridge large spans, but they are nonetheless a beam.  A bond beam, on the other hand,  is meant to tie CMU walls together (generally at the top of a wall). If you set a bond beam at the base of a wall, you are not "tying" anythying together. By pouring a beam above the footing in order to structurally resolve questionable bearing (in a know and limited area) you would essentially be pouring a concrete grade beam again. To do that with CMU "bond beam" forms (at essentially grade) would be silly as well as futile.

How bout a little teamwork............ (post #210151, reply #19 of 33)

Until the credentials of all involved are clearly spoken or at least listed in the profiles............

 

and since the OP hasn't been here since Saturday...............and maybe the work resumed on Monday.........

 

Why don't we try to "discuss" these things instead of ...............whatever it would be called.

thanks.

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


http://www.quittintime.com/

 


Calvin, I almost hoped a good (post #210151, reply #20 of 33)

Calvin, I almost hoped a good flame war was breaking out, to remind me of the webx days.  This place has been pretty dull lately.

ha ha ha...... (post #210151, reply #21 of 33)

Good thing doright hasn't picked up on this engineering.

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


http://www.quittintime.com/

 


Who do you think was pouring (post #210151, reply #22 of 33)

Who do you think was pouring the concrete?


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

my 2 cents (post #210151, reply #27 of 33)

Calvin,

If you don't care for the "flavor" of the discourse here, then you are free to ignore it. Last time I checked, participation or even monitoring of this forum was not considered mandatory--for anybody.

BTW, if you want to discuss anyting personal with me (like my creditials*), then send me a private message with your phone #. I'll be happy to call you.

Cheers!

* another aspect of this forum's participation which is not mandatory. IMO, If you can't discern information from knowledge w/o the posting of creditionals, then perhaps you should question your own participation.

dead (post #210151, reply #32 of 33)

If I'm free to ignore it I would guess I'd be free to comment on it, no?

and I've been questioning my participation on this forum for over 16 yrs.

 

If you can make it up to Boston for the Fest in August, we could sit back and b.s. about all this and most anything else.  It's a good way to put a face on a name. 

Na zdrave!

A Great Place for Information, Comraderie, and a Sucker Punch.

Remodeling Contractor just outside the Glass City.


http://www.quittintime.com/

 


you sure are (post #210151, reply #33 of 33)

You'd guess correctly.  In fact, I've always enjoy your comments-- and I have never made an attempt to "curb your enthusiasm" so to speak.

Merely pointing out the parity in extending that same courtesy to others.

Thanks for all the advice (post #210151, reply #23 of 33)

Thanks for all the advice received, very grateful for the guidance on how to proceed.  I am going to try to answer all questions.  The cistern was filled with water, must have been for the original house as there was an old clay pipe going to the house from it. Not sure of size or if he reported it as it was removed before I saw it.  Also havent found out if soil was compacted.  I am in WV, city limits.

Should I request he provide compaction results?  A retired contractor looked at the transit beam and said it was reinforced and does resolve the issue.

Forgot to clarify the beam is (post #210151, reply #24 of 33)

Forgot to clarify the beam is one piece of concrete, with small grooves every foot on one side, it's 6'. The steel isnt visible, just that the retired contractor told me it was there.

The rebar was placed on the (post #210151, reply #25 of 33)

The rebar was placed on the bottom of the hole dug and the transit beam is placed inside the first row off block on top the footer, still slightly below grade...though maybe not the first line.. 

What are the approximate (post #210151, reply #26 of 33)

What are the approximate dimensions of the beam?


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Why aren't you asking the (post #210151, reply #28 of 33)

Why aren't you asking the retired contractor about the compaction and whether or not you should ask for test results? Personally, I wouldn't bother to test because the test can only measure the top few inches of the fill. Although, I suppose there are very sophisticated sonar tests nowadays that could provide some meaningful results. Sounds expensive though. And the contractor will make you pay for them (and rightfully so) since testing probably isn't in the contract.

Your description of the situation is still very sketchy and I, for one, am not sure of what happened and how it has been resolved. But, you seem to be saying that work is proceeding and you've entrusted the structural integrity of your new home to a retired contractor. I wish you all the best.