Gap under post-tension slab?

[hal1]

Sorry for the ramble....

I'm having a house built by a Taylor-Morrison, a major builder here in Arizona (can't see any reason why I'm not allowed to mention their name). It's not custom, just one of 5 floor plans in a planned subdivision.

There is a gap under the slab at the front that is the porch. I can freely move a stick around under it but I couldn't tell you how far back the gap extends

The superintendent seemed very casual when I showed him, as if it's common, and said they will fill it in with dirt when they grade the yard.

Should this be enough? Surely packing in dirt can't really add support.
If it's a post-tension floating slab is the tension rods enough to hold it together?
Could this corner just snap off under its own weight?

I don't want to sound naive, but if Taylor-Morrison builds a thousand homes a year in Phoenix wouldn't they know what they doing and what should be a concern or not?

One foundation guy I spoke to said..

"It needs to be pressure grouted (mud jacked). Packing dirt in there after the fact will not work as nobody knows how big the void really is and you cannot really pack dirt sideways for anything more than a few inches. Yes you should demand that this be done properly. I suggest you contact the structural engineer for the project and get his recommendations."

I'm guessing the I could tell the superintendent that I want to talk to their structural engineer? - but then I'd be trusting him too.

They've got a $6,000 deposit, and I'm not sure how much I can demand they do. I can't afford to walk away from my deposit and prices have gone up a lot recently so I don't want to start a new build. But I can't afford to have the front of my house snap off either.

Am I being too ****, or can I trust that their solution is sound?

 

[Richard Cranium]

I agree, they need to do more then pack dirt under it. Pressure grouting would be what I wanted.

 

[guspech750]

I've drilled and taken soil samples inside and around homes and buildings that eventually the concrete fails due to such gaps. The gaps usually will get larger as it rains and water enters the cavity and finds new ways to exit the cavity while possibly washing away more material. I've seen some pretty large gaps under homes and buildings due to the use of bad fill and many other reasons. Of course once the foundations starts to fail, the walls, roof, floor all are affected and begin to fail, break, sag etc etc.

You better get that taken care ASAP. And not with just packing in some dirt.

I'm not an engineer by any means. I've been operating drill rigs for an engineering geotechnical and environmental company for over 20 years. I've seen my fair share of foundation issues due to various reasons.


Sent from The White House on taxpayers dimes.

 

[matt_i]

Its wrong and they know it. First action in any "large" builder is to deny that it has any affect on the outcome.

Despite your deposit, your leverage comes at closing when you do or do not sign the papers and the builder is holding a large, finished, taxable structure on their books not to mention the sum of all the materials + labor.

I would write them a letter with pictures (or email) stating defect and asking for remediation. I'd followup with some more at regular intervals. If no action, then bring it up at closing.

 

[COSMOS]

I've run 5 million and down commercial projects, special inspections are required on many phases, based on the pictures that issue should have been resolved prior to pouring. Pressure grouting is an option in addition you might call http://www.azrm.net/ for an opinion and has been in the valley for about 25+ years and has come up with some unique ways to repair structures, footings, concrete slab and foundations...

 

[Cyberbear]

What I can't understand is why a "floating" slab was used, and why there are no footings around the perimeter to properly support the weight of the home? Judging by the pictures, it appears the pour was done on top of fill dirt that was not properly compacted and has now settled. Take your photos to your building department and ask them what they think of this situation. If this is an example of the quality of work being performed, it's probably good that you know now rather than later when it's too late to cure any problems, things that could haunt you long after the builder has skipped away with your money, leaving you to pay for their poor workmanship. Perhaps you need to demand answers to these obvious questions, and obtain a written guarantee and bond from the builder that can be enforced in a court of law, they paying all legal fees to make the job right. Too many times crappy builders have gone bankrupt leaving the home owner holding the bag.

 

[COSMOS]

Most of the builders here in the valley have went to "post tension slab" they have there advantages when working in tight residential lots as opposed to footing/stem/slab pour. Less prone to termite infiltration at the slab surface as their are no control joints to crack.

Structurally more than enough to bear the weight of the house and turndowns where needed at the edge of the slab for the truss bearing walls.

Hal1, do you a have a better picture of pre-pour conditions in the area outlined after the slab pour.?

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[cspcrx]

As he stated that style of slab is very normal here in the phoenix area. I have had two homes built, both post tensioned, and they had no footers.

I would be asking for a meeting on this one.

 

[hal1]

Hal1, do you a have a better picture of pre-pour conditions in the area outlined after the slab pour.?

This is the best pre-pour picture I have, but it doesn't specifically show that area (which would be to the left at the bottom of this pic). - but yes, there does seem to be a footer around the house so I don't know why that fron edge would be so narrow. Based on the form boards on the right I'm not sure how earth could have caved in after the concrete was poured. It seem the poured concrete would have prevented that.

If I waited until closing, wouldn't it be harder to prove after they've shoved dirt in it? I guess my first move now would be to talk to the superintendent? After that there should be some inspector that would handle the foundation part?You can see from teh second pic that it's "just" the porch in front, but I think it was poured as one slab.

Thank you everyone! Keep the suggestions coming and please follow this thread for me.

 

[FordTruckWench]

What do the two black pipes in front of the house connect to? I presume they connect to the plumbing risers scattered around the slab. I wonder if the trench dug for this plumbing has settled. If so, the gap might extend under much of the slab!

 

[hal1]

I've run 5 million and down commercial projects, special inspections are required on many phases, based on the pictures that issue should have been resolved prior to pouring. Pressure grouting is an option in addition you might call http://www.azrm.net/ for an opinion and has been in the valley for about 25+ years and has come up with some unique ways to repair structures, footings, concrete slab and foundations...

Hehe, how cool. It was indeed Bob at Arizona Foundation Solutions that told what I quoted here in my OP.

 

[COSMOS]

What do the two black pipes in front of the house connect to? I presume they connect to the plumbing risers scattered around the slab. I wonder if the trench dug for this plumbing has settled. If so, the gap might extend under much of the slab!

Sewer "Y" cleanout, one of the biggest issues I have had on any ground up building was compaction (tenant improvements were just as bad in an existing building) in the trenches at the certified building pad. Threaten them with compaction testing and the subcontractor shapes up in a hurry, I have a little hair left..

 

[COSMOS]

Hehe, how cool. It was indeed Bob at Arizona Foundation Solutions that told what I quoted here in my OP.

I keep forgetting they had changed their name years ago.

 

[Big Bad Dad]

I would have them saw cut it, break it out, fix whatever settled, and re-pour it. PERIOD. Document all this with pics, and if they refuse, you still hold the cards at settlement time.
"He who has the gold has the power." Once you pay, you are DONE.....

 

[COSMOS]

I would have them saw cut it, break it out, fix whatever settled, and re-pour it. PERIOD. Document all this with pics, and if they refuse, you still hold the cards at settlement time.
"He who has the gold has the power." Once you pay, you are DONE.....

Big no no on a post tension slab, cut one cable and the slab integrity is compromised, hydraulic grouting would be optimum. I have had numerous 2nd floor commercial buildings where you're required to xray prior to even drilling/coring a hole through a post tension floor. The homes I have looked at in the past have the concrete stamped at the garage door opening indicating a post tension slab.

 

[ilovevocs]

What is off to me is that their had to be something their to support the concrete during the poor.

How deep is void? Seems like your unsure. I would take a shovel and start digging. Wouldn't take long to get perspective on just how large the anomaly is.

I agree that "dirt" should be the last thing "packed" into it. If they do fill it full of something it needs to be properly compacted or its just going to be a superficial / aesthetic fix.

 

[MacTexas]

I can add nothing to the conversation but I have a post tension slab so I will be interested in the outcome.

 

[COSMOS]

Hal1, when was the slab poured in relation to our most recent rain, it appears after looking at the pictures a bit more and reading some of the other responses the sewer trench was not compacted back correctly and the rain may have settled the "fluff" backfill....

 

[Jaguar Fan]

I would not accept it.

The builder wants to cover up the problem and move on to the next subdivision. There will be cracks in your slab, of course. If you have tile in that area, the tile will crack. My guess is the home warranty you receive will state that concrete cracks are not covered - they will be considered normal, although yours will be much worse there than anywhere else in your house or in your neighborhood.

You should meet ASAP with the President of Taylor-Morrison Arizona. Don't take "no" for an answer.

 

[Git]

What is off to me is that their had to be something their to support the concrete during the poor.

Yep - otherwise the concrete would have filled it in. Looks like to me they pulled the forms and some extra concrete was stuck to the board and it came out when the board did.

 

[hal1]

Hal1, when was the slab poured in relation to our most recent rain, it appears after looking at the pictures a bit more and reading some of the other responses the sewer trench was not compacted back correctly and the rain may have settled the "fluff" backfill....

It was raining on the day of the pour. Not heavily, but it was steady.

 

[hal1]

My real estate agent (mine, not the builder's) has an engineer that works for a civil engineering company that tells her that since it's a post-tension slab it is not depending on the dirt to stay in place, which means is can withstand an earthquake where the earth is moving underneath. Other than that last part, does that make any sense?

Even though she (my agent) will get a commission when I buy this house, she has been a great advocate for me, and knows that even if something fall through (pun intended) on this house, there's another I would buy and she will still be my agent and get her commission. She has been great in facilitating this issue with me.

 

[hal1]

I spoke to the builder's RE agent (he was about as useless as a limp d*ck). I asked to speak to the structural engineer. He said he wanted to talk to the superintendent first to get an explanation. I told him that if the super doesn't have the answers I'm looking for that I want the engineer to meet with me and my guy (I'll pay for the a Certified Foundation Repair Specialist) to explain to us why his dirt packing idea is right. I'm hoping that this Foundation Repair Association has some qualifications, and can be udes as a reason to get out of the contract if Taylor-Morrison wont help.

 

[wssix99]

This is not a big deal. Looking at the sequence of pictures, there was some spill-over from the pour. It looks like when the contractor cleaned that spilled concrete up around the forms, it pulled up some of the base material with it.

All they need to do is rod some gravel underneath and it will be fine. If that worries you, just have them put some more concrete in the space and you'll be even more fine.

Surely packing in dirt can't really add support.

Correct. You need something that's non-compressible, like gravel or concrete.

If it's a post-tension floating slab is the tension rods enough to hold it together?
Could this corner just snap off under its own weight?

It depends on how much weight is on it. It looks like that area is a porch. It that the case? If so - this is really not a big deal. The post-tensioning alone would be enough to hold the whole family hanging out there if you did nothing at all.

One foundation guy I spoke to said..

"It needs to be pressure grouted (mud jacked). Packing dirt in there after the fact will not work as nobody knows how big the void really is and you cannot really pack dirt sideways for anything more than a few inches. Yes you should demand that this be done properly. I suggest you contact the structural engineer for the project and get his recommendations."

I think this person was missing some context. That void just goes back a number of inches, right? If so, this foundation guy is confirming you can just pack stuff under there.

I don't want to sound naive, but if Taylor-Morrison builds a thousand homes a year in Phoenix wouldn't they know what they doing and what should be a concern or not?

Companies like this are typically not builders. They sub all of the real work out to other companies. If you are lucky, the same subcontractors will be doing the work on all the houses in your subdivision, so you and your neighbors will have the same issues to deal with and the last ones in to the subdivision should have more of the wrinkles ironed out.

Historically, these types of companies make their money by flipping the land. (Turning it from empty desert or farms in to a community.) The only reason they put a house there is so that they can sell the land to you and make their profit. Since subcontractors are doing all the work, there is very little profit left over for them to make off of the actual construction.

Tayolor-Morrison probably has their own Construction Manager on the job and they may or may not have engineering-type knowledge/skills. They may have some of their own workers, may sub 100% of the labor, or could have blended teams. They may also give their subs Taylor-Morrison t-shirts to wear at the site so that they look like employees - even if they aren't.

BTW - For this issue, I think you deserve a t-shirt. I bet if you ask your Construction Manager for one, he'd be able to hook you up with one on-site! (You are spending enough money to deserve one, right?)

 

[COSMOS]

My real estate agent (mine, not the builder's) has an engineer that works for a civil engineering company that tells her that since it's a post-tension slab it is not depending on the dirt to stay in place, which means is can withstand an earthquake where the earth is moving underneath. Other than that last part, does that make any sense?

Even though she (my agent) will get a commission when I buy this house, she has been a great advocate for me, and knows that even if something fall through (pun intended) on this house, there's another I would buy and she will still be my agent and get her commission. She has been great in facilitating this issue with me.

Your agent and her engineer friend are a couple of dumbasses.
.
.
.

She may have mis-interpreted or mis-quoted what the engineer stated, so please feel free to correct the statement and educate the rest of us...

 

[Zeke]

Finally, wssix99 brings forth some good information rather than the typical knee jerk reactions. I'm surprised someone didn't say, "Lawyer up!" Well, the thread's not done yet so that may still happen.

Yes, looks like a porch to me given the columns. Pretty obvious. While I wouldn't expect to see this, I wouldn't piss my pants knowing it's there. Mud jacking is reserved for places where pressure can work in favor of the mud being pumped in. That pressure will fill in a void or raise the slab. Trying to pump into that at an open edge is tantamount to squeezing toothpaste onto a tooth brush. Keep squeezing and you will find toothpaste on the floor wasted.

I've had similar situations come up over my years in the trades. Most were easily corrected. As wssix99 pointed out, using a ram tamper and jamming some gravel or even dry sackcrete in there will handily take care of the sinkage.

I would watch the area immediately beyond the porch for sinkage. There was excavation done there for the pipes. Might need to be compacted. They can do that with the ram tamper.

 

[COSMOS]

Do a Redneck Superintendent soils compaction test first: Use a 5ft. piece of #4 rebar step out a foot from the slab at the void and see how far it pushes into the soil, then do the same inside the void. More than an inch you have confirmed that the soils were not compacted back correctly...

 

[hal1]

Oops, I need to re-post the pics

 

[BillK]

HA,
How about calling the building inspector ? Not sure if this is a code issue or not but you are paying his salary and its at least worth a phone call. They have to sign off on it anyway.

 

[hal1]

HA,
How about calling the building inspector ? Not sure if this is a code issue or not but you are paying his salary and its at least worth a phone call. They have to sign off on it anyway.

Interesting, I had just thought the same thing this afternoon.

Everyone here has been very helpful. Most said it needs to be fixed, a few said it's not a huge issue. Perhaps the best route would be to go with what the building inspector says. Again, maybe I'm naive, but I'll assume he isn't in the pocket of Taylor-Morrison.

 

[hal1]

I think someone pointed out that is was this over-pour spot where the gap is originating

 

[Git]

Yep - post 21 at the top of the page

The only 'void' is probably from the removal of that excess concrete. Otherwise - why would there be a void there - the wet concrete would fill it in when they poured it

 

[hal1]

Yep - post 21 at the top of the page

The only 'void' is probably from the removal of that excess concrete. Otherwise - why would there be a void there - the wet concrete would fill it in when they poured it

Interesting that that is outside of the form board though.

That's what I was thinking. So did removing that concrete burr pull some of the gravel with it. (they put gravel on the dirt before pouring)

I can get a stick under there about 2 feel, after that I start scraping dirt. *If* that's all three is, does that change the discussion?

 

[COSMOS]

Do a Redneck Superintendent soils compaction test first: Use a 5ft. piece of #4 rebar step out a foot from the slab at the void and see how far it pushes into the soil, then do the same inside the void. More than an inch you have confirmed that the soils were not compacted back correctly...

Interesting that that is outside of the form board though.

That's what I was thinking. So did removing that concrete burr pull some of the gravel with it. (they put gravel on the dirt before pouring)

I can get a stick under there about 2 feel, after that I start scraping dirt. *If* that's all three is, does that change the discussion?

After enlarging the picture the "excess" "spillover" concrete looks intentional...

It could be fixed much easier provided the compaction is OK , excavate past the edge of the concrete, a little bit of forming above the level of the bottom of the concrete and pour in a 1 bag mix of slurry for 100% compaction, drop a ******** in there for a few seconds for good measure and your done, no need for a tamper etc., I have done and seen this done numerous time in trenches and onsite soils testing companies have signed off on this method....

Any geo-tech or structural engineers on this board disagree.?

 

[Big Bad Dad]

Big no no on a post tension slab, cut one cable and the slab integrity is compromised, hydraulic grouting would be optimum. I have had numerous 2nd floor commercial buildings where you're required to xray prior to even drilling/coring a hole through a post tension floor. The homes I have looked at in the past have the concrete stamped at the garage door opening indicating a post tension slab.

OH.. I am not familiar with concrete slabs with cables in them. Did not pay attention to the "post tension" words. I have not seen one, to my knowledge. This is not what we do in our area. Please educate me a little...
Thanks

 

[hal1]

OH.. I am not familiar with concrete slabs with cables in them. Did not pay attention to the "post tension" words. I have not seen one, to my knowledge. This is not what we do in our area. Please educate me a little...
Thanks

In the pre-pour pics the cables you see running across are within a sleeve. They are anchored to one side of the slab and stick out the other side. After the concrete is mostly cured, they are pulled tight from the other side with thousands of pounds of pressure. This is compacting, or putting tension on the slab, keeping it tightly together and prevents cracks.

 

[wssix99]

So did removing that concrete burr pull some of the gravel with it. (they put gravel on the dirt before pouring)

Yes, gravel/base goes down first, then the forms, then the concrete is poured. Some of the cement will ooze down and lock in to the gravel. In this case, it looks like your slab has thickened edges and they pulled up some dirt with that spill-over that was attached to the form.

If the dirt on that edge was loose enough to pull out, tamping some more back in will be good enough to restore it about to where it was originally. (On top of that, you have the added insurance/strength of the post-tensioned slab.)

^ That being said, your pictures look like you might have had some additional erosion after that initial event. The voids around the edge look a little larger than would be expected - but that might be the magic of internet photography... I'd get down there to confirm how far back they go.

How often do you get rain? Is the roof situated in such a way that (before the gutters have been put on) it is dripping along the edge of your porch? That could be making the void larger. If that is the case, filling with gravel ASAP will put a stop to that action.

I can get a stick under there about 2 feel, after that I start scraping dirt. *If* that's all three is, does that change the discussion?

Honestly, you should get down in the trench on your knees and feel in there with your hand. That will give you better information and give you some credibility. If you talk to contractors with dirt on your hands and clothes about your concern vs. them seeing you squatting there poking around with a twig - you'll get a totally different reception. (They will never take you seriously if they see you do the later.)

Perhaps the best route would be to go with what the building inspector says.

I would not go there. It will just piss off a lot of people, including the inspector. No matter what - everyone is going to be pissed off at the end of your project. (That is the way of construction.) However - you want to delay the state of pissed-off-ed-ness as long as you can. The longer people can stay happy and civil, the less money you will waste. This is not an issue you want to start a war over - or even a small disagreement. Those things will come later!

 

[Falcon67]

What I can't understand is why a "floating" slab was used, and why there are no footings around the perimeter to properly support the weight of the home?

Same way they do houses here, except nobody uses post-tension. Slab-on-grade, maybe 18" x 6"~12" trench on the perimeter and some beams cut through the sand. Just scrape the Mesquite scrub off the lot and get after it.

 

[Git]

After enlarging the picture the "excess" "spillover" concrete looks intentional...

In the pic - you can see there are two areas of "excess" concrete

If you look REALLY close - you can see that each of these areas is around a metal stake that holds the form boards and the metal stake sticks up above the surface of the concrete so when they are screeding/finishing it makes it more difficult to work around

 

[COSMOS]

Interesting that that is outside of the form board though.

That's what I was thinking. So did removing that concrete burr pull some of the gravel with it. (they put gravel on the dirt before pouring)

I can get a stick under there about 2 feel, after that I start scraping dirt. *If* that's all three is, does that change the discussion?

Yes, gravel/base goes down first, then the forms, then the concrete is poured. Some of the cement will ooze down and lock in to the gravel. In this case, it looks like your slab has thickened edges and they pulled up some dirt with that spill-over that was attached to the form.

If the dirt on that edge was loose enough to pull out, tamping some more back in will be good enough to restore it about to where it was originally. (On top of that, you have the added insurance/strength of the post-tensioned slab.)

^ That being said, your pictures look like you might have had some additional erosion after that initial event. The voids around the edge look a little larger than would be expected - but that might be the magic of internet photography... I'd get down there to confirm how far back they go.

How often do you get rain? Is the roof situated in such a way that (before the gutters have been put on) it is dripping along the edge of your porch? That could be making the void larger. If that is the case, filling with gravel ASAP will put a stop to that action.




Honestly, you should get down in the trench on your knees and feel in there with your hand. That will give you better information and give you some credibility. If you talk to contractors with dirt on your hands and clothes about your concern vs. them seeing you squatting there poking around with a twig - you'll get a totally different reception. (They will never take you seriously if they see you do the later.)




I would not go there. It will just piss off a lot of people, including the inspector. No matter what - everyone is going to be pissed off at the end of your project. (That is the way of construction.) However - you want to delay the state of pissed-off-ed-ness as long as you can. The longer people can stay happy and civil, the less money you will waste. This is not an issue you want to start a war over - or even a small disagreement. Those things will come later!

Piss off the inspector, the inspector's job is to protect the eventual owner of said structure from deficiencies and shoddy construction work to some degree as is the general contractor's responsibility to inspect his sub-contractors work prior to inspection.

If the jobsite superintendent brushed me off the next would be the city inspector, project manager of the sub-division and not necessarily in that order.This can be kept civil now that it is small issue and before the sidewalk is poured, after that it will cost substantially more to remedy..