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I’m monitoring the construction of a new home for a daughter. The builder began construction of a stem wall footing, and the subsequent ready mix pour of a 4″ + on grade slab in mid September.
The concrete sub was unprepared for the ready mix trucks he had scheduled for early morning delivery, so the start 2200 sq. ft. pour was delayed until about 11:00 am. The door sill form were not set the day prior amd they had the wrong elevation on the laini, so it had to be redug, those forms reset and then the ‘bug treatment’ done again in the disturbed area. I waited for the 1st ready mix load and then departed to do some useful work in my shop.
Needless to when I returned about 3:00 the skys were threatining in the Tampa Bay area. All of the slab was poured and the sub had began usinf his mechanical, rotary trowel. About 4:00 pm the skys opened – about 3″ to 4″ of rain began. They tried for about 15 minutes to float the slab, but gave up and departed for a ‘beer.’ I left, but was told by the GC that they had returned and worked into the darkness.
It slab was pot marked and dod not have the expected finish the next day. But, several days later, a 1/16″ crack began in the center and proceeded North. I called the builder on his cell phone ( he was now out-of-town). He sent his wife to confirm the crack. I returned to the site two or three days later, now there was 5 or 6 cracks.
Needless to say, the builder insisted, for the last several months, while the construction proceeded, that he would get a inspection by the ready mix vendor, his friends, fellow builders, etc.
Now it is crunch time, the flooring is a mix of ceramic tile, hardwood and carpet over the concrete slab. He is now prepared to seal the cracks with a two part, nozzel mixed, epoxy and then apply a sealer.
Upon an inspection a week ago, another crack had begun in the garge floor slab. We also noted a 1/4″ to 3/8″ heav in the center of the kitchen floor. Perfectly placed between the range, sink and opposite wall cabinets.
Earlier that week, I watched the same concrete sub pour the final yard or two of the driveway, sidewalk, it dawned on me that there was no wire in the form.
In a ‘punch list’ we demanded that the contractor fix the slab, prior to any additional interior work. We also asked him to cut open the salb, about 2′ square to repair the heave. I related my observation about no wire in the walkways and asked him to notify me to observe the kitchen cutout. He then informed me that there was NO WOVEN WIRE FABRIC in the slab or in the driveway / sidewalks.
He states, and I know that the ready mix was enhanced by a vinal thread like component. He contends that the trade no longer uses the woven wire fabric reinforcing because it must be above the earty and visqueen moisture barrier, on pedastals and that the cement masons always force the wire downwards as they pour and level.
The plans called for a 4″ trowel finished slab of 1500 PSI, with the Woven Wire Fabric, Type 2500, over a 4 mil Visqueen on 95% compacted soil.
Concrete notes specify the wire to conform to ASTM A-185 amd another notes states that the concrete shall have a 2500 PSI compressive strength at 28 days. A further note spells out the spacers, chairs and bolsters to support the reinforcing in place.
The question. Is he correct in deleting the woven wire fabric and its support items, Does this synthetic fiber additive to the ready mix substitute for the mesh?
Or is the cracking going to continue and destroy the ceramic and wood and carpet by hydronic seepage?
I have an electrical background, but currently own a Custom Cabinet shop. But desperately need some solid feedback con concrete.
Thanks for reading this lengthy posting
Replies
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ADK Jack stay out of this one, it's too long for you. :)
John,
First of all we've never had a lot of sucess using fibre type additives, whether steel or vinyl.
Secondly rain in itself won't neccessarily cause cracking although 3 to 4 " is a heck of a lot of rain.
This does sound like a problem of no mesh ( if you were on site for the first truck didn't you notice that mesh hadn't been installed or that there was none on site ? ) causing the cracking.
I'd be getting an independent engineers report on the whole job.
Don't you have inspections at slab stage prior to pour?
Sounds like this will come down to your contract documents and how well they have been drawn up.
Lots of luck
*This slab post has more problems than an entire house should have.First, why wasn't this project stopped before it reached this stage?2200 sq. ft, 4" slab, fibremesh in 1500 psi and everyone is surprised that the entire thing is cracking. It's a miracle that the slab hasn't left town.It's too late to discussed spilt milk at this point, but this is what happens when inexperience supervises the unknown.Get an Engineer to look over the project for an opinion.Because you assumed the role of site supervisor, you're pretty much out of luck as far as legal recourse is concerned, you were there and suffered or allowed the work to be done and are acting at the completion stage.Too little too late.It's unfortunate that you had to do "useful work" in your shop while this was going on.Good luck.
*First of all it should be Welded Wire Fabric. I won't speculate on cracks etc. But...If the contractor deviated from the written specs. then he should be liable for all problems regardless of their cause. Check your local law.
*
What about the subsurface soil being properly compacted? It sounds like there is movement occuring under the slab. Your contractor is correct in stating that the concrete subs don't know how to keep the WWF at the proper location withinb the slab but that is no excuse. I have found that slabs that have fiber tend to crack wherever they want. Were there any control joints placed in this slab, not that it would have helped with all the cracking that is occurring.
*What about the subsurface soil being properly compacted? It sounds like there is movement occuring under the slab. Your contractor is correct in stating that the concrete subs don't know how to keep the WWF at the proper location within the slab but that is no excuse. I have found that slabs that have fiber tend to crack wherever they want. Were there any control joints placed in this slab, not that it would have helped with all the cracking that is occurring.
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John,
Bulldozer and lawyer time.
Jack : )
*"...hasn't left town." That's a good one, Gabe.
*Sounds like the contract was quite specific, and that the builder's unauthorized substitutions (if they were anything other than mistakes) are not of equivalent value (fiber for metal mesh? even I know that's hooey). Band-aids won't turn it around. If the concrete is cracking like this now, imagine what it will look like it 10 years -- you have a lot more to be worried about than the floorcoverings!Get an independent concrete pro to give you a written evaluation & work something out right away.
*Andrew,Did you try to say this?... b "John, b Bulldozer and lawyer time. Jack : )
*Doesn't sound asprofessional. Also I'd get the lawyer before the bulldozer.
*I once got a lawyer before a bulldozer, but he was too fast and managed to get out of the way...
*I knew (!) that was coming, and started to make a joke of it, but worried no one would get it... Get the builder before the bulldozer, then head over to CT to help Mongo with his rose garden.
*
JJM:
It was said that "the contract was quite specific"-not so. The plans call for 1500 psi and Notes specify 2500-you'll end up in a pi**ing contest w/ the Contractor as to which governs. BTW, I have never heard of a 1500 psi mix unless it is used as backfill-
b never
use less than 2500 psi for structural concrete-thats your daughters first problem.
Second, the contractor is correct that WWF usually ends up in the dirt, even when supported. If you want to reinforce a slab (even residential), use rebar supported properly on chairs. Third, poly fiber is
b not
a substitute for reinforcement. Finally, the torrential rain probably brought your 1500 psi slab down to 1000 psi or worse and doomed any chance that this slab would perform as intended.
My advice as a PE is to get a good lawyer w/ construction defect experience and take steps to get contractor to replace slab.
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John,
I'm real sorry for you. This is the dark side of construction. A project is started with the best of intentions and goes to ruins.
Best of luck resolving this mess.
*John,If you don't have what it takes to "Get the lawyer and bulldoze," then their is a great alternative you must use. It's my choice often with things like cars that have unsolvable problems, etc....b Sell the problem to someone else.Be fair, don't lie...just show all and take the best offer and smile again...b You'll feel like the free-est man on Earth.J
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March 12, 1999
Jack
Not my decision to "Get a lawyer and bulldoze !" Nor can I sell, the property and under construction home are my (NYC based) daughter's future residence.
I'm just a Dad, trying to watch out for her interests, offer advise, contact local subcontractors and vendors, etc., while she continues to work in the Big Apple and I try to keep an eyeball on the construction.
I did suggest to the Builder and my daughter that the slab be demolished immediately after the 2nd set of cracks began in late September / early October, before the concrete block walls were erected. But the GC told her that the cracks were only 'surface' cosmetic cracks. I've writted five 'Punch Lists' since December - Item #1 on each has stated "DO NOT PROCCED" with any construction until the slab is corrected. But ..... dads can only advise their
children
I greatly appricate your comments.and everyone else who has contributed who has had input this past week.
Yesterday, 03/11, We hired an independent, certified, hone inspector to review the cracked slab conditions. He will perforn that inspection at 4:00 pm today. In the interum she has halted (finally) the job progress pending the inspection report.
Thanks again,
John J. Meyer
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I've been doing residential construction here in central Florida for a year now having moved here from Seattle. Everything you've learned about what not to do with concrete is what is done. The chief inspector for the county told us "everybody knows that more water improves concrete" 8-10" slump is not unusual. Some pour so wet they don't need to screed, just flatten it out with darbys and it's done! Any WW is laying on the ground under the slab and due to the climate in the rainy season 1-3" in a day is not unusual either. The odd thing is sometimes they come out ok. Other times problems as described. There is SO MUCH building here that the subs pretty much do what they want and if you don't like it you can find someone else. Who will do it exactly the same way. The only solution is to hire your people to do it and it takes a good sized builder to have their own concrete crew running. It should be inspected before the pour and a compaction test is also required by the county here and I would expect also in Tampa.
It is very difficult and time consuming to resolve these types of problems. My suggestion would be an isolation membrane under any tile and a vapor barrier under the carpet. Cracking slabs are just the way it is here and I've found it easier to treat the problem rather than try to cure it. I know that sounds fatalistic but you cannot beleive how different it is here.
'When in Rome..'
*John, Post the results if you can about the inspection.
*Gregory,All I've heard is that nothing matters in Florida, and I've heard your same song from returing carpenters for years....I won't hire someone who's worked down there now.J
*John first sorry about your problems with the slab. As I read your post I'm not sure if you are acting as the general or just as a construction manager on this house? Now let me rant about concrete some. First off concrete has been around for some time now and most of the stuff is straght forward. b When it comes to residental concrete most of the people don't know a thing about what they are doing. Just because this is the way you have always done it don't make it right. Most concrete for residental is at 2000psi to 3000psi this is for side walks and stuff. Even house slabs will work in the footers are done right. I wonder if, as you read your spec's if you have mixed the spec's for the sidewalks and the house? Your cracks are a result of poor steel placement(none) and lack of compacted fill. (Compacted is not having the backhoe run over the site a few times.) If the sub was able to run the trowel machine on the slab the rain would only hurt the finish(temp/curing being equal) not produce the damage that you are seeing now. Next questions is there any lift of the slab? Did the sub place any grade beams in the pour? Did anyone check compaction? As far as fixing this I wouldn't use the mix.
*
JJM:
You may consider having the slab cored by a concrete coring/cutting firm and bringing to a local testing lab (in NYC you'll find lots and not as expensive as you would think). In situ concrete should develop 70% of its design strength (which at 1500 psi is still not sufficient IMHO), but will give you documentation of the substandard strength of the slab. If its less than 1200 psi you have good cause for getting the contractor to remove it. Please address this problem post haste and document everything in the event you end up in court.
*You can get lawyers before bulldozers if youpromise the lawyer the litigation job after the accident.
*
I'm monitoring the construction of a new home for a daughter. The builder began construction of a stem wall footing, and the subsequent ready mix pour of a 4" + on grade slab in mid September.
The concrete sub was unprepared for the ready mix trucks he had scheduled for early morning delivery, so the start 2200 sq. ft. pour was delayed until about 11:00 am. The door sill form were not set the day prior amd they had the wrong elevation on the laini, so it had to be redug, those forms reset and then the 'bug treatment' done again in the disturbed area. I waited for the 1st ready mix load and then departed to do some useful work in my shop.
Needless to when I returned about 3:00 the skys were threatining in the Tampa Bay area. All of the slab was poured and the sub had began usinf his mechanical, rotary trowel. About 4:00 pm the skys opened - about 3" to 4" of rain began. They tried for about 15 minutes to float the slab, but gave up and departed for a 'beer.' I left, but was told by the GC that they had returned and worked into the darkness.
It slab was pot marked and dod not have the expected finish the next day. But, several days later, a 1/16" crack began in the center and proceeded North. I called the builder on his cell phone ( he was now out-of-town). He sent his wife to confirm the crack. I returned to the site two or three days later, now there was 5 or 6 cracks.
Needless to say, the builder insisted, for the last several months, while the construction proceeded, that he would get a inspection by the ready mix vendor, his friends, fellow builders, etc.
Now it is crunch time, the flooring is a mix of ceramic tile, hardwood and carpet over the concrete slab. He is now prepared to seal the cracks with a two part, nozzel mixed, epoxy and then apply a sealer.
Upon an inspection a week ago, another crack had begun in the garge floor slab. We also noted a 1/4" to 3/8" heav in the center of the kitchen floor. Perfectly placed between the range, sink and opposite wall cabinets.
Earlier that week, I watched the same concrete sub pour the final yard or two of the driveway, sidewalk, it dawned on me that there was no wire in the form.
In a 'punch list' we demanded that the contractor fix the slab, prior to any additional interior work. We also asked him to cut open the salb, about 2' square to repair the heave. I related my observation about no wire in the walkways and asked him to notify me to observe the kitchen cutout. He then informed me that there was NO WOVEN WIRE FABRIC in the slab or in the driveway / sidewalks.
He states, and I know that the ready mix was enhanced by a vinal thread like component. He contends that the trade no longer uses the woven wire fabric reinforcing because it must be above the earty and visqueen moisture barrier, on pedastals and that the cement masons always force the wire downwards as they pour and level.
The plans called for a 4" trowel finished slab of 1500 PSI, with the Woven Wire Fabric, Type 2500, over a 4 mil Visqueen on 95% compacted soil.
Concrete notes specify the wire to conform to ASTM A-185 amd another notes states that the concrete shall have a 2500 PSI compressive strength at 28 days. A further note spells out the spacers, chairs and bolsters to support the reinforcing in place.
The question. Is he correct in deleting the woven wire fabric and its support items, Does this synthetic fiber additive to the ready mix substitute for the mesh?
Or is the cracking going to continue and destroy the ceramic and wood and carpet by hydronic seepage?
I have an electrical background, but currently own a Custom Cabinet shop. But desperately need some solid feedback con concrete.
Thanks for reading this lengthy posting
*
DISCRIMINATION!
That's funny Jack, cause ther's some states thatshouldn't be mentioned when applying with me too!
Blue