# Wood over slab is cupping



## r4r&r (Feb 22, 2012)

Leaking sewer line. Being in Garland I would guess cast iron sewer and a 20+ year old house. It could be saturating the ground in that area.


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## ArtisanRemod (Dec 25, 2012)

To answer an earlier question, a moisture meter can be bought online or at any better tool store. they range from $100 to $400 roughly. Test in various areas at different times and record the data, hopefully you will see a pattern. I liked the earlier suggestion to see if the floor has room to expand. A lot of guys run the floor to tight to masonry work.


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## rocks911 (Jan 29, 2013)

r4r&r said:


> Leaking sewer line. Being in Garland I would guess cast iron sewer and a 20+ year old house. It could be saturating the ground in that area.


3500 Sq. Ft. 1 1/2 story Firewheel home built in 1997, no cast iron. Let me say again, I've had 2 different plumbing companies test for leaks of sewer and fresh water, no leaks detected. No evidence whatsoever of leaking water or sewer.

Not all of Garland is 20+ years old with rotting cast iron.


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## rocks911 (Jan 29, 2013)

Thanks everybody for the replies its given me something to think about. I'll let you know if I ever find something difinitive.


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## astor (Dec 19, 2008)

rocks911 said:


> This area is not on an exterior wall, its interior. The closest thing that might be a culprit is the fireplace. I have gone over the fireplace, had a custom chimney cap made, had the brick waterproofed and checked the flashing, its all good. The entire fireplace is as dry as a bone. I checked it from the top brick to the bottom brick and there is no sign of any water.
> 
> Had plumbing leak test done, by two different companies, both found nothing.
> 
> ...


Interior wall or not, water leak from window sometimes find its way 20-30 feet in any direction interior of the house.(depends how many stories there) Leak may re directed to a new path. Thermal camera will show any water inside the walls, if not you can eliminate that.

Did you have any plumbing work done before this started?
Is there a bathroom above that section? Condensation on pipes may cause as well. You have to realize,not much water needed to cause all this.
I am not sure what type of test the plumbers doing, but pressure test may not show very small leak.

I had called for a similar problem years ago, there was a basement in that case, I found my way to the basement and see a new water heater installed. Yellow traces on the ply,never-less, when I place my hand between pipes and the ply holding more than a minute,very small, almost impossible to see,like "a very fine fishing line" water was hitting the ply, believe it there was not a drop on ply. Upstairs floors was just like yours.
A good infrared (thermal) camera can show you the source of the water or at least how much the spread is.


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## jamestrd (Oct 26, 2008)

wow...deja Vu!


Rocks,

you wont know much without at least ripping boards in affected areas.

i recall you saying the problem leaves, then goes away and returns to different areas..

the only answer that will remain constant is this.

cupping is an unbalanced equilibrium of moisture form the underside to the top of the board.

simply the bottom is "wetter" than the top.

can you get dry cupping? sure..this is when moisture is pulled too fast from the top,but the underside is still wet..

changing from summer to winter would cause this in environments that warrant it.

you're in Texas..which I would think is a dry heat and do you even heat homes there?..

pulling a few boards in the area may start to answer questions..the subfloor can be read too..

you wont find out much more than that and I doubt you will fix it without ripping the floor..

reading the top of a board now wont tell you anything..it will read normal to dry most likely..


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## r4r&r (Feb 22, 2012)

Texas is anything but dry in the summer. In the area the OP lives the humidity is pretty high, not Houston high (I have literally sweated in the shower in Houston it is so friggin humid) but it isn't dry here by any means.


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## lawndart (Dec 3, 2006)

How does the area feel when walking on it? Is the subfloor underneath loose? Is there a bounce to it?

Are the edges of the boards curling or, is the center of each board raised?

How do you clean the floor? How often? Who is cleaning the floor?

Are you using a steam cleaner on the floors?

Is the subfloor level, without any dips/low spots?

What were the RH readings?


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## rocks911 (Jan 29, 2013)

lawndart,
The area is not spongy at all, still rock solid.
The edges are curling up, the center of the board is lower.
Dust mop. Though I dont see why it would matter, if I was wet mopping it I would think that everywhere would have a problem, as a matter of fact maybe a wetter top would do some good.
No dips, no more or less than any solid concrete slab.
My RH readings were 23% if my gauge is to be believed.


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## MIKE ANTONETTI (Jul 17, 2012)

Contact Scott Avery of modern tech floors in Portland Oregon , he gave a seminar at Surfaces on installation failures & solutions in Vegas this week, he knows the industry and networks with the most knowledgeable in the hardwood flooring industry, just post back to help improve the industry. 
Some of the answers here sound very reasonable, but as said miles away its hard to predict.


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## jamestrd (Oct 26, 2008)

r4r&r said:


> Leaking sewer line. Being in Garland I would guess cast iron sewer and a 20+ year old house. It could be saturating the ground in that area.



good cal..i had this happen in a townhouse we installed..one area of the slab remained wet..cause some wall problems as well..
.if i remeber correctly..there was something to do with AC as well under the slab..


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## lawndart (Dec 3, 2006)

rocks911 said:


> lawndart,
> The area is not spongy at all, still rock solid.
> The edges are curling up, the center of the board is lower.
> Dust mop. Though I dont see why it would matter, if I was wet mopping it I would think that everywhere would have a problem, as a matter of fact maybe a wetter top would do some good.
> ...


Rocks911,

What your are most likely experiencing is a rare occurence called "dry cupping". This is caused when the top of the board is drier than the bottom.

If your RH readings are correct then 23% RH is most likely the problem. Go purchase a humidifier to maintain a perfect 50% RH in the area, and the problem will go away.

I'm certain it is not related to moisture underneath your floor. If it were a moisture problem from a leak, or moisture vapors in the subfloor, your boards would be crowning in the middle (center of board raised, with lower edges)

A couple more questions.
What type of heating system is in the area?
Are the areas that exhibit this curling close to vents or baseboard heat?


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## rocks911 (Jan 29, 2013)

Thanks for the continued interest lawndart,

Another forum on wood floors suggested I get a humidifier, so its up and running, though I'm not to 50% yet...running it up slowly. Its amazing how much water the air can take when its as dry as a bone. I wish the installer had mentioned ANYTHING about floor care and/or precautions.

I have central gas heat and while there isnt a vent at that location there is a return, pretty much right above it. Its quite a return as well, with the bedroom door closed the movement of air makes a whooshing sound. 

I dont know why it would do it this year and not last, or why the cupping I experienced was here this year when it was over there last year. But it did occur to me that the return could be pulling moisture from that area.

I just wished it were in some other area, I walk past there fifty times a day,. in any other room, particularly my guest bedroom it wouldn't make me feel nearly as sick to my stomach...know what I mean.

I'm a patient guy, so I figured I'd throw a rug over it (I think that actually helped the spot that cupped last year because it kept the moisture in the wood) and hope it went back to normal as last years cupping floor did.

My home is apparently cavernous because I have a humidifier http://www.amazon.com/Essick-Air-4D...20&keywords=Essick+Air+Whole+House+Humidifier
running nearly all the time to keep my downstairs at about 40% RH, might have to purchase another.

Thanks again for the continued interest, I appreciate it


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## lawndart (Dec 3, 2006)

rocks911 said:


> Thanks for the continued interest lawndart,
> 
> Another forum on wood floors suggested I get a humidifier, so its up and running, though I'm not to 50% yet...running it up slowly. Its amazing how much water the air can take when its as dry as a bone. I wish the installer had mentioned ANYTHING about floor care and/or precautions.
> 
> ...


Rocks911,

You are right, the return vent is pulling the moisture from that area, and causing "dry cupping"

Most humidifiers will tell you how much maximum area they cover. I'm willing to bet yours is not rated for 1,200 square feet, so running another one is needed, or you could always ditch the stationary humidifiers, and install a humidifier directly to your furnace.

Good luck and keep us updated


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## the rock (Feb 27, 2011)

I second 5 star.We don't install natural hardwood over a slab NO MATTER WHAT.You will have problems.


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## jamestrd (Oct 26, 2008)

lawndart said:


> Rocks911,
> 
> What your are most likely experiencing is a rare occurence called "dry cupping". This is caused when the top of the board is drier than the bottom.
> 
> ...


Really?.... You are quite certain from only a few posts? And his problem is spotty and moves every winter?...... 

Wow..... I must bow before you. 
And listen lawndart... Listen well.. Only for your education.. 

The situation you explain is called "crowning".. When the middle of a board is higher than the edges. 

This occurs when a floor is "cupped" (floor wetter underneath and never dried properly) 

The floor gets sanded in its cupped state. Before being stabilized.. Because the board is not sitting flat with edges curled,, the sanding is in effect sanding the raised edges of the board only and not the center,,, but the bottom edges of the boards is still off the subfloor.. 

When the equilibrium of moisture is reached.. The bottom of the board sits flat and true again.. But because sanded to early.. The edges have to much removed.. Creating an effect of the board higher in the middle because too much was removed fro the edges. 

Working for LL may or may not teach you that.. But growth and numbers may make you choose to ignore it,,,


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## jamestrd (Oct 26, 2008)

lawndart said:


> Rocks911,
> 
> What your are most likely experiencing is a rare occurence called "dry cupping". This is caused when the top of the board is drier than the bottom.
> 
> ...


One last thing.... Perfect RH readings are considered to be 35 -45 % in our area... Its the true comfort level of humans and wood interestingly enough. 

Rocks.. You need to remove re floor in he effected section now and read bottom of oak and subfloor... 

It will! Hep you start to understand your problem


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## jamestrd (Oct 26, 2008)

lawndart said:


> Rocks911,
> 
> You are right, the return vent is pulling the moisture from that area, and causing "dry cupping"
> 
> ...


Holy crap


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## lawndart (Dec 3, 2006)

James,

First of all, I don't like the way you address me. 

I've seen "dry cupping" which is a site related problem. It's actually very common in NYC within co-op apartment buildings here, and based on the photo, and information Rocks provided me, and others, I'm almost certain this is his problem.

You are welcome to your opinion, and I won't mock you for it. How about you try extending the same courtesy.

Being that you are right down the road from me, I'd be willing to show you how I run my business, and what the LL installation program is all about. I'd be open to hearing your suggestions.


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## lawndart (Dec 3, 2006)

forget it.


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## rocks911 (Jan 29, 2013)

I'm not ripping anything up.
What cupped last year is perfectly fine this year, I expect this to be no different.

I'm not a flooring expert and dont want to start ripping up my flooring and I havent found any flooring contractors in the area that I trust.

I've had every opinion under the sun as to why this is doing this, and NONE of them adequately explains the floors behavior. Until I find THE reason, which apparently I never may, I'm not doing a thing but putting a rug over it.

Thanks for the continued attention, I really do appreciate it, always open to new theories. If anybody knows of a competent flooring company in the Dallas area please drop a post.

Thanks, and dont fuss with each other on my account.


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## jcrdesign (Feb 4, 2013)

putting plywood over plastic is not a good practice because it will trap moisture between the layers causing mold or other issues.


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## rocks911 (Jan 29, 2013)

jcrdesign said:


> putting plywood over plastic is not a good practice because it will trap moisture between the layers causing mold or other issues.


There is information/opinions out there that indicate that method is the standard:
http://www.hardwoodinfo.com/articles/view/pro/28/241

My contractor left out the *"apply cold, cut-back asphalt mastic with a notched trowel (50 sq. ft. per gallon). Allow to set for two hours. Unroll 15-lb. asphalt felt or building paper, lapping the edges 4" and butting the ends. Over this, apply a second similar coating of mastic and roll out a second layer of asphalt or paper in the same direction as the first, staggering the overlaps to achieve an even thickness." *Part though. He just laid plastic over the slab then plywood. 

There is an amazing divergence of opinions. What some say should never be done is exactly what others recommend. A homeowner like myself is left to wonder...and eventually spend more money. 

I know that I'll never have another wood floor....been there, done that, if I only knew then what I know now. This is pretty standard for my luck though, my friend who recommended the contractor has the same floor in his house...no problems, looks beautiful. Clearly this is a tempremental art.


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## MIKE ANTONETTI (Jul 17, 2012)

The problem -please acknowledge is moisture- 

Testing prior to installing is critical.
Unbreached vapor barrier under slab- mandatory
Balanced hvac system , some hygrometers in each room will help , write it down each week to see if you can see a pattern, problem or not you should have these anyway.
Moisture (not flooding) causes 1billion dollars of damage a year, not only to wood floors but to all flooring, even carpeting.
Don't take it out on the wood, I would guess just like a patient you can't diagnose without testing equipment on site by competent qualified person.


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## jcrdesign (Feb 4, 2013)

*wood flooring*

If, for some reason you or anyone else is interested, Lumber Liquidators has the most comprehensive, tech advanced (gauranteed) underlayment/VB/insulation products available in ALL comm. /res. applications...I've put down about 40 + floors in Florida, Tenn, NC, MA and NH never had an issue (oh yeah and ALWAYS verify credentials - and DETAILS of any project - of installer as you would have your own verified - take pride)


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## rocks911 (Jan 29, 2013)

MIKE ANTONETTI said:


> you can't diagnose without testing equipment on site by competent qualified person.


I completely agree. Now who that person would be is a complete mystery to me. I've had a company out that was recommended by staff at NHLA on their forum. A kid came out drove a nail (probe) into my floor, connected his meter and said "eeeh, not too bad" and I asked what does that mean and he replied "it might just go back to normal over time" and that was it. He put his meter back in its case, tried to remove the nail (he couldnt, I wrestled it out with pliers) and left. I knew no more than when I started.

Finding the "competent qualified person" as with most things is the most very difficult part.

While your precations all make sense, and I now monitor my homes RH more than my cell phone, I cant help but laugh at my circumstances. All of this I share with my friend who has the same floor installed by the same contractor and he has never spent one minute of worry or monitoring that the perfect environment be maintained 24x7. I dont think I can ever go on vacation again. 

Ya just gotta laugh :thumbsup:

I enlarged my works, I built houses for myself, I planted vineyards for myself; ... All was vanity and vexation of spirit. - ecclesiastes


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## madmax718 (Dec 7, 2012)

If the floor board wasnt' acclimated, then nailed down, then sanded and sealed, there will always be some unequal pressure somewhere- whether its the tongue, the groove, all pulling on the nails in every which way. Once its sanded it was even worse, you only have one flat plane. the bottom side is still all over the place, and will offer different expansion rates.

thats just my two cents. I always leave my boards for a week along with the plywood so they are both equalized to the same environment.


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## madmax718 (Dec 7, 2012)

the vapor barrier under the plywood was pretty much standard practice. Even if you puncture the VB, the idea is still that the VB would allow the amount of moisture released to be much slower- even with hundreds of nails pounded through it.

Yes, I agree with everyone. It is a moisture issue. I just think that the floor was sanded with the wood already warped out of shape. So it looked good at the moment, and now you have all sorts of weird issues.


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## rocks911 (Jan 29, 2013)

madmax718 said:


> I just think that the floor was sanded with the wood already warped out of shape. So it looked good at the moment, and now you have all sorts of weird issues.


I have to wonder about the wood. I remember the contractor said he had a hard time finding the wood, it was the "last place I called" which didnt feel good to me at the time. 

The contractor cant even be found, so clearly he didnt have a lot of faith in his work. I thought I was doing good by going with a reference, even looked at several of his floors, but none that were years old. It didnt occur to me that his modus operandi was to get it down then disappear.

Live and learn.


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## madmax718 (Dec 7, 2012)

if your seriously having issues with it.. and its bothering you so severely, it might be worth it to rip up a few corner pieces and check how true they are. 

Do you remember what brand it was? (it might be stamped into the back side). Some mfg's have warranties "if installed properly".


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## rocks911 (Jan 29, 2013)

Its not bothering me that badly, this is just an ongoing conversation of sorts. 
As is often said "if it aint broke dont fix it", and I cant say what about it is broke, so I'm fine with watching and waiting.

But I do actually have some pieces he left, I'll have to look


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## jamestrd (Oct 26, 2008)

lawndart said:


> forget it.



My apologies for coming off like a D.ck...and the condescension..
it was super bowl and had too many Johnny Blacks..

but to be "certain" from some posts without reading or seeing is impossible.

I mentioned dry cupping earlier in the thread as well, but I am not Certain and i don't think this is the case at all..
these issues i have seen in poorly made engineered products only..
too dry an area would certainly cause gapping and shrinkage in solid before cupping.

and even if this is the case, why only in certain areas that shift on him every year?

there is an imbalance and we need to stick to the basics..cupping is always a moisture problem.

Pulling a few boards and reading the underside and subfloors will start to tell more. more.

as for LL..you cant sell me on them..they went 0 for 2 with me..
no more.
your biz is your biz..
I'm not here to try and change that..


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## madmax718 (Dec 7, 2012)

james: its perceived cupping that is the problem! :clap:

If it was crowned when the contractor sanded it, and then sanded it flat, when the wood flattend out, then it looks like cupping! 

Im just stirring up [email protected]#. Just trying to figure out the problem.:thumbsup:


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## jamestrd (Oct 26, 2008)

madmax718 said:


> james: its perceived cupping that is the problem! :clap:
> 
> If it was crowned when the contractor sanded it, and then sanded it flat, when the wood flattend out, then it looks like cupping!
> 
> Im just stirring up [email protected]#. Just trying to figure out the problem.:thumbsup:


interesting theory..but the boards would have had to be cupped first..then sanded...then crowned..then sanded again for this to occur..

since this occurs every year and in different areas..that theory can 's stand..the whole floor would present itself that way.


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## msv (Aug 5, 2009)

Did you end up checking the expansion space in that general area? Even being too tight under the door jam can put enough presure on a floor to do that...


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## rocks911 (Jan 29, 2013)

I did not pull base to see, but the worst part of the cupping is right at the door jam and I have no idea how much space he allowed. I dont know what space is supposed to be provided but I do know that when the floor was done I went back with the same base moulding with no shoe moulding so clearly there isnt a lot of space.

I just loathe ripping anything up, I'm adopting a wait and see approach. If I could find a flooring contractor that I had any faith in I'd have them over to solve this for me but to date I havent found that person.

I threw a rug over it....problem gone.


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## msv (Aug 5, 2009)

I can understand how this is not a big enough problem to make it worth getting into ripping floors up. Don't want to restate what 100 people already said, but you want to get a balance between the moisture under and on top of the wood. 
Another thought(common sense moslty): it might be that the air return is causing a much stronger dry air flow in that particular area. I would also try one of those plastic deflectors that you usually place on feed vents. Direct it up, so that it doesn't pull straight from the floor.
The door jam thought is based on previous experience(it was the only place where a floor wasn't allowed expansion) and it is right in the middle of where the issue occurs( you said some winters it occurs on the other side of it, by the bookcase).
Sorry to hear about your flooring contractor vanishing, we all hope he's okD)..


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## rocks911 (Jan 29, 2013)

Thanks for the post, I think all of what you said is true, thats why I'm just taking a wait and see approach. What cupped last year is back to a condition where you would never know it had cupped.

I think its the combination of the HVAC return/very low RH/a pinch point of sorts in that area not allowing expansion. I'll see what she looks like in 6 months.

Till then I'm :whistling past the area rug.


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## adamsb (Aug 25, 2005)

Please start somewhere by pulling the baseboard off. We are all wondering how tight the floor is to the wall. We're not asking to demo the whole floor up. Just use a good sharp utility knife and cut the caulk joint at the top of the base and loosen with pry bar and carefully remove it. Then post some pics of it. Thsnks


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