Good evening- My elderly parents are building with a tract builder south of Houston, TX (clay soils). I live close and have some construction experience so am keeping an eye on it as it is going up. Their post tension slab on grade foundation was poured early August, 2021 and as of now, the slab has not been tensioned. The sheetrock has been delivered and installation is scheduled for Sept 28, 2021. There is a continuous crack running the length of the slab through the center of the house, visible inside and outside. About 99% sure the crack appeared in the last week.
I know shrinkage cracks are common, but if it appeared 6 weeks after the slab pour could that be it? Concerned it is a structural crack that will continue to cause problems if they go ahead and tension and finish the build. Going to try to find a local structural engineer for an inspection/opinion as well…
Would love some opinions from professionals. I don’t see how to add photos so I will link to an album
I’ve seen them wait 6 days to stress the tendons but not 6 weeks. I’d question the builder and ask what are you waiting for.
I have seen cracks come together after the tendons been stressed but it depends on the amount of debris inside the cracks, and that job site is a mess.
Without being there and seeing the whole picture of the location, size and any differential movement it’s hard to comment on the foundation issue. Good call to request an engineer to observe it.
@afrydenlund nailed it. Tensioning usually happens within the first week and cracks usually close up afterwards.
You should contact the builder to verify that tensioning of the slab hasn’t been completed. If it has, it might be worth your time and money to contact an independent SE that doesn’t work with or for the builder.
If the post tension cables are the only reinforcement in the slab they should have tensioned the cables long ago. Exposing a post tensioned slab to hot dry weather is a recipe for shrinkage cracks. They could have minimized the crack size by wet curing the slab for 7 to 10 days, but I am guessing that didn’t happen. Post tensioned cables are typically designed to apply 50psi compression on the concrete design to carry 3000 to 4000 psi. So there is no advantage to waiting that long. As mentioned once debris enters the cracks closing the gap is not feasible. Have you read the home construction contract? Does the City or County have building codes?
I am reading a copy of the contract tomorrow as I sit in my car outside the home tomorrow waiting to talk to the city inspector, engineer, construction manager (who hung up on me), and the post-tensioning contractors.
The city of Pearland has codes and building inspectors. The only foundation inspection they do occurs prior to pour to verify cable/rebar placement and plumbing specs etc. They do not come after usually, but are tomorrow because I spoke with a sympathetic inspector today.
OK- so this is what is happening. The slab is cracked and is going to be tensioned tomorrow. the builder’s engineer is going to take a look and likely write a letter certifying that the foundation is fine which will satisfy the city and the Builder. I spoke with the construction manager (who is NOT happy, lol), Gehan corporate (construction mgr’s boss) who essentially told me they would tension and have the engineer write a letter), and the city, who said if the engineer writes a letter saying the slab is fine, they cannot do anything further.
My parent’s likely have an “out” of their contract because the foundation plans (which I still do not have a copy of) were likely not followed. The BIG question is: Should they bail? They are 75, so this is not a LONG term home for them. The stress of starting over with another builder or finding and dealing with finding an existing home for sale in a very hot market is not appealing either. Will a post tension slab that starts out in 2 pieces fail quicker than a post tension slab that is tensioned while in 1 piece? If it ‘fails’ within the 10 year warranty, how do you repair? piers? is it a big deal? They do not need an ongoing hassle, they already have lingering heath issues. Just trying to help them make an informed decision.
I am having a hard time getting a third-party structural engineer willing to look at their slab. Any suggestions? Houston area.
See if the cracks close up after they do the post tensioning and see what the engineer’s letter is certifying. Does he certainly the slab will function properly for xx number of years or does he just certify the post tensioning was done properly? Bottom line is will the final appearance impact the sale of the property when the house sells. If it does it would not be unreasonable to ask for a discount to offset the damage. When you buy a new car you don’t expect to pay full price if it has a dent in the side. The Post Tensioning Institute recommends tensioning the cables between 3 and 10 days or when the concrete reaches a minimum strength based on concrete cylinder testing.
Yes to both. Are the Building Codes and other appropriate standards enforced? Only when convenient to do so.
What typically happens here in Texas, especially in areas with large amounts of building, are the local Authority Having Jurisdictions rely heavily on the Builder’s Third Party Engineering and other (mostly other) inspections. Can you say “Fox guarding the hen house”?
Over the years it has become increasingly apparent that the mantra with AHJ’s in Texas are “See no evil, hear no evil, speak not evil”. If the AHJ’s were to perform their jobs builders would only stop building in their jurisdiction and move on elsewhere where the AHJ follows the mantra. It’s all about the money, the faster they can slap up homes the faster the municipalities can collect large property taxes!
To cover your three points/questions above in bold.
What the City (AHJ) has told you is only partly true. As I tell my clients there are only three people/concerns that have any control over the Builder. One is the Builder and we know for the most part they are not going to change anything if it costs large amounts and they can get away with it. The other is obviously the buyer since they have a contract with the Builder to build a safe and habitable home. The other is the AHJ who can stop construction at any time for any reasonable cause. The AHJ can force the Builder to provide an explanation why tensioning has not occurred at this late date and/or can force them to perform additional testing or other beyond a simple visual inspection by an Engineer. However that is completely up to the City to do.
As for the foundation failing within the 10 year warranty period you should obtain a copy of the actual Builder warranty and read it closely. You will be very surprised what the Builder is calling a “failure” for the foundation. It is literally a home that is not structurally safe. However between now and then it allows for very wide margins of problems that can be passed over as “not covered” and yet leave the homeowner very unsettled about the condition of the home. If it never passes that “not covered” threshold the Builder has many “outs” that can leave the homeowner holding the bag anyhow.
As for an Engineer for your own review you can start with the membership list at The Foundation Performance Association (FPA) located there in Houston https://foundationperformance.org/ . The FPA also has a very wide array of useful documentation to help you better understand the issues.
I camped out at the house this morning and met with the city inspector. On the record he is going to require a letter from the EOR stating that “in his professional opinion the delayed tension, premature loading of the slab, and continuous crack should not affect the slabs performance” I also asked if he could require the EOR to perform baseline relative elevation surveys. Haven’t heard back.
Off the record he suggested we read the contract super super close and find a way out. I agree that my parents will always question and not be super confident in the home, which sucks. this is their last home (they are 75) and moving closer to me for help as they age.
This afternoon when I drove by the city had put a stop work order on the house. The cables were not tensioned today (as I was told) so we will see what the builder/EOR/city inspector hash out in the next few days.
I found an engineer or two from the Foundation Performance directory who have availability to come out. Differing opinions on whether to come out pre-tension/ post-tension or both? Level surveys and visual inspections were mentioned. What else would a foundation evaluation of this type include?
Have also gotten numbers for a few real estate attorneys. Haven’t spoken to anyone yet.
Yes even if the survey comes up as perfectly level. In the future if you suspect foundation movement, regardless of the suspected cause, you would use the baseline survey as a comparison to demonstrate the movement.
What would have been interesting, and possibly useful, was to perform a baseline survey before tensioning the cables and then a follow on after tensioning the cables. This could be used to demonstrate the amount of movement of the two sides of the slab which might help explain any framing anomalies that occur as a result of the tensioning after framing, if any occured.
Now that they have tensioned the cables, and drawn the two sides of the crack back together, has there been any discussion, or has the City required, that the crack be properly sealed? The FPA site had information regarding proper sealing of cracks. You would have to search it out and it may be in the publications I previously listed.
Apparently from your first post this crack did extend to the exterior. It is expected to also have been fairly deep in the slab. The crack is a possible point for water migration that either originates from below the slab or near the edges if the crack extended below grade. Even small amounts of water migration can cause issues with wood flooring and even other types of flooring. It is best to prevent that by properly sealing the crack prior to flooring installation.
I will have to see what the city requires as far as sealing the crack. I went by again today and the crack debris had all been swept away, so I assume the engineer was there?
Also notice 8 or 10 small divets in the concrete that were not there previously. They are mostly in pairs. Any idea of the cause or significance?
There are so many different causes for the divots it would be difficult to tell just from a picture or even a visible, on site inspection of them. As long as there is nothing wrong with the concrete at pour, or handling during pour, then these can be easily and effectively repaired. This is what I would recommend for divots and cracks.
On your next visit take a screwdriver or other flat blade device and scrape around the interior and edges of them. What you would be looking for is significant flaking/spalling (typically it occurs in layers) that just continues on and widens until it reaches hard, sound concrete. If is just a little before sound concrete not a concern. If it keeps going it might indicate concrete issues.
Watch the build closely for more divots, additional cracking, and deterioration around divots and cracking. Typical (notice I did not say “normal”) concrete shrinkage cracks can still develop. It is the flaking/spalling as well as crack displacement (one side higher than the other) that should be reviewed.
Have you hired a good Inspector to perform phase inspections for your home?
I do have a structural engineer coming to do a foundation evaluation and baseline elev. survey. it’s not really a rush now that the slab has been tensioned. Waiting to read the Engineer-of-record’s report on the foundation before scheduling my guy. Also waiting to hear what the city has to say about the violation of stop-work-order and engineer’s report.
Tensioning usually happens within the first week and cracks usually close up afterwards.
