# Hardwood floor buckling



## Just Bill (Dec 21, 2008)

All of the things you mentioned likely added to the problem. The house should have been dryed out(propane heaters don't dry out anything), the flooring should have sat in the room where it would be installed, opened, for 3-6 wks before being installed. 

Why would you put screws thru that beautiful oak?? Get a flooring professional, not the guy that installed it, to have a look see. Maybe they can salvage it.


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## ccarlisle (Jul 2, 2008)

Hmmm, let's see: IMO if the floorboards haven't individually 'cupped', or have resumed their flat state, then there's a humidity balance that has been reached between them and the surroundings. So OK there...now if what you call 'buckling' is a spongy feel when you walk on it, that may be a subfloor or underlayment installation issue. Not enough screws, insufficient layout overlapping, even missing paper (if any was put down), for example. You may have success reaching that with screwing from underneath, but not 100% sure about that...

But if the buckling is happening around the perimeter, I'd want to be sure there was enough room left for expansion/contraction by leaving enough gap. Is there a gap or is something in there?


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## twracc (Mar 31, 2005)

I was wondering if I could weight the floor down so it was flat, then screw up through the sub-floor and into the oak from underneath. Sub-floor and oak is 1 1/2', so I figure an inch and a quarter screw would keep it below the surface. I could do that easily. 
Because the areas are not that big, ie. 1 1/2' x 3' (with the 3' parallel to the baseboard), I thought maybe I could lay a cleat or piece of angel iron on the affected area, drill 2 5/16 holes down through the surface, and thru-bolt to pull it down flat. With that done, I could screw up from the bottom like in the first suggestion. Remove the cleat and it should stay there. The oak is finished fairly dark, so to hide the thru-bolt holes I'd just fill them with an oak plug, stain and finish and I doubt you'd see it.

Because the affected areas are adjacent to the baseboard, I suspect the installer didn't leave enough, (or any) space between the wall plate and the flooring. If you dry the subfloor enough, can it actually shrink enough to close that gap and cause the flooring to bunch up? That's what it looks like, but that would mean the room just got narrower by a quarter to a half inch or so, and I find that hard to believe.


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## twracc (Mar 31, 2005)

Ccarlisle. We were typing at the same time. I'm certain it's not a subfloor issue. It's T&G, every joint tight, glued down by the framers and I personally screwed it down. And it's on open web trusses 12" deep with no span more than 13". This is definitely an issue where there's a space (picture a big bubble) between the flooring and the subfloor. To check the gap between the flooring and plate means I'll have to pull the baseboard to inspect. If there is none, is there a saw that will cut that close to the wall or is pulling up floor and replacing sections the only way to restore the gap?


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## ccarlisle (Jul 2, 2008)

I see...is this a floating floor or was every floorboard stapled/nailed down? nailed to each other or into the subfloor OSB?

Either way but especially if a floating floor, there should be a 1/8" or 1/4" gap between the finished planks and the wall to account for the expansion of the floor due to humidity. At least that is done in tiling, but I see no reason not to do the same. If there's no gap there and the floor expands, the floor will bubble as you say. Somewhere. It won't cup but a number of the boards will "tent".

If the boards that tent are around the outside, that points to "no expansion gap" or some of the boards were nailed down in a floating floor configuration. If all the boards were nailed down, then something in the installation process seems off.


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## twracc (Mar 31, 2005)

Not floating. Everything nailed down. Staples I believe. Just like the pre-finished stuff from Bruce, etc. The only difference is that it's quarter sawn (rift actually) and not prefinished. I believe you're right about the "no expansion gap" part. I wasn't around for the install, but my wife says they did leave a gap, and she's sure because she wondered if the baseboard/shoe would cover it. 
Anyhow, the fact that it seems to "go down" when you stand on it (you don't actually feel it go down, but you sure hear it), can you see any problem with me weighting it down and screwing up from the underside? I'm pretty sure the sub-floor and the hardwood are the same moisture content now. What I don't know is whether the two, being different material, would expand and contract the same and at the same time.


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## ccarlisle (Jul 2, 2008)

Well, if its not floating then it must be stapled...not to each other but to the underlayment. So how come they're up? Bad staples? In any case, where the boards are not attached, that's a weak point in the floor and hence the expansion there.

By corollary, if they are attached, there's no real need for an expansion gap _for the floor_...only a small one for each board along two walls of the perimeter.

IMO, you should be able to screw them from underneath...


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## Gary in WA (Mar 11, 2009)

Osb got wet- insulators saw mold- rosin paper protected------- Rosin paper has a permeance of about 50----- it let the moisture right through. Semi- permeable is asphalt covered paper, a vapor retarder.

When it rains while I frame houses, I drill 1/2" holes in the sub-floor where the water pools. The perimeter of the deck gets all the *extra* water from the walls as well, it gets *soaked*. After framing, and the rough-in is done, the insulator spreads plastic vapor barrier under the crawlspace. 

The oak sucked up any moisture present in the OSB, and you probably have a good crop of mold there. I saw rosin used as floor protect over wood flooring in a remodel, until it got wet from shoes and left pretty pink footprints. Be safe, GBAR


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## HardwoodGuy (Jun 7, 2008)

> ... maybe 35 sq ft affected


That's a clue there. And rift sawn shouldn't move that much. Sounds like an isolated problem. Water intrusion, leaks in the wall, roof above? What's underneath?


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## Daniel Holzman (Mar 10, 2009)

All wood flooring needs an expansion gap around the outside, regardless if it is rift sawn, flat sawn, or quarter sawn. See www.nofma.org/Publications/tabid/82/Default.aspx for a complete discussion of proper installation technique for wood flooring. If your floor gets wet from the top, the top of the boards expand, and the boards cup downward (convex). If the floor gets wet from below, the bottom expands, and the board cups upward (concave). Since your boards are not cupped anymore, this indicates that the wood has achieved a relatively uniform moisture content, which by the way can be checked with a moisture meter if you choose to.

Since the boards have lifted off the subfloor, this suggests an expansion issue. I have T&G oak flooring in my house, and every summer when the humidity is at a maximum, a specific area in the middle of the floor buckles upward. As in your case, you can feel it, and see it as well. Come fall, it dries out, and the buckle disappears. No cupping in either case, however there simply is not enough expansion room to handle the full width of the boards. You can check on the link above the expansion for different types of wood, and based on the relative moisture difference between maximum and minimum, you can determine the required gap.

And yes, if the gap is insufficient, there is a special type of offset blade saw that can cut immediately next to a wall, I think it is called a cabinet saw. I have never used one, but you can rent them from my local rental place. Very handy when you need to cut a groove next to existing cabinet work, such as for tile or floor installation.


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## Gary in WA (Mar 11, 2009)

Thank you, Daniel, very informative. Toe-kick saw. Be safe, GBAR


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## twracc (Mar 31, 2005)

Sorry guys. I started this thread and didn't get back to finish it. I think Daniel Holzman's reply is what I'm dealing with. Virtually all cupping gone. BTW, the cupping was at the joints, not in the middle of the planks. Between it being winter and my ERV going, I had the humidity down into the high teens. Way too dry. Installed a Honeywell Steam Humidifier and couldn't be happier with how I can control humidity. Back to the floor. I think the problem is no gap around the perimeter. Should I pull thebase boards and cut one. Baseboard is only primed at this point, so while I don't relish the thought, I'm prepared to do it. What I'm not sure of is whether this will permit the floor to lie flat again and prevent the noise when I walk on the (currently) affected areas. Someone said a while back that, yes, I could screw up through the subfloor from underneath. Is that a good idea? I was also wondering if it would be possible to drill some kind of hole from underneath and inject something like PL adhesive in, not really to fill the gap, but to re-fasten the flooring to the subfloor. 
Dave


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## twracc (Mar 31, 2005)

And Daniel H. I see your on right now, but it's getting late for me and 5:00 am comes early. I'll check tomorrow to see if you get this. 
Thanks again


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## Goldtor64 (May 13, 2009)

*Hardwood floors over concrete slab....*

I have hardwood floor, t&g, installed over a subfloor attached to the concrete slab. I have buckling around the exterior perimeter in two areas, and in the hall at the wall. I also had buckling in the dinning room about 3 months after installation, at perimeter. The installer came out, ripped up a section of the floor expecting to find water. None was there, then he took a reading and said too much moisture in the slab. I now believe that was not exactly true, but install tile there instead. Now I have the issues in the areas mention above. The floors look great and you can only really tell it when you walk in the areas. I suspected that the subfloor was nail down securely. They use a gun which shot the nails into the subfloor and slab. I can tell it is the subfloor that has become losse and not the hardwood.

Is there a way to repair without ripping up the floor. Can I screw from above and fill the holes and finish the areas?


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## twracc (Mar 31, 2005)

You're asking if you can screw it down from the top. My question earlier in the post was can I screw up from below (ie from the basement) into the hardwood to pull it down to the subfloor that way. I'd like to think there's some other option than having to relay the floor. Especially since it was finished on site and I'd be concerned the stain might not match the original. Mine's been down less than a year. Dave.


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## What have I done (May 28, 2006)

I would try screwing from underneath. nothing longer than 1 1/4" though!

should draw the floor down nice and tight. Could use some finish nails from the top-side also. but I wouldnt use too many. even though the are small they show up!

Good luck


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## Jason S (Jun 1, 2009)

Goldtor64 said:


> I have hardwood floor, t&g, installed over a subfloor attached to the concrete slab. I have buckling around the exterior perimeter in two areas, and in the hall at the wall. I also had buckling in the dinning room about 3 months after installation, at perimeter. The installer came out, ripped up a section of the floor expecting to find water. None was there, then he took a reading and said too much moisture in the slab. I now believe that was not exactly true, but install tile there instead. Now I have the issues in the areas mention above. The floors look great and you can only really tell it when you walk in the areas. I suspected that the subfloor was nail down securely. They use a gun which shot the nails into the subfloor and slab. I can tell it is the subfloor that has become losse and not the hardwood.
> 
> Is there a way to repair without ripping up the floor. Can I screw from above and fill the holes and finish the areas?


I have this same problem in two rooms. I'm borrowing a flush cut saw and will cut the areas that are tight. I've already removed the shoe and base board. Hopefully this will work. If not, I'm thinking about using mason screws thru the oak, sub-floor, then thru the concrete. I hope someone else has a better fix!


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## twracc (Mar 31, 2005)

I'm no expert, but I am curious. You have a subfloor over a concrete slab. What's the subfloor consist of. Is it 5/8 ply or OSB on 2x4 sleepers?


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## Jason S (Jun 1, 2009)

They put down 1/2" plywood for a nailer. I just finished cutting through the 3/4" hardwood and 1/2" ply. Hopefully my floors will settle in a few days. If not, I will have to screw them down through the slab.


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## Goldtor64 (May 13, 2009)

*Jason S - Buckling*

I just pulled the shoe molding and the wood is flush again the base. I am willing to bet that the subfloor is also. I am going to try cutting my floor at the perimeter also this weekend. Jason, my installation is just like yours. If my floors don't settle I have already purchased the screws. I will update after cutting the floors to relieve the pressure.


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## twracc (Mar 31, 2005)

Goldtor64 said:


> I just pulled the shoe molding and the wood is flush again the base. I am willing to bet that the subfloor is also. I am going to try cutting my floor at the perimeter also this weekend. Jason, my installation is just like yours. If my floors don't settle I have already purchased the screws. I will update after cutting the floors to relieve the pressure.


Looks like we're on the same page regarding the flooring/subfloor having been installed without enough clearance from the base of the wall. In my case I have a basement below. For you guys on a slab though, I'm still wondering if you could use a flush cutting saw, get some PL adhesive under the floor and weight it down. I'm sure the Pros are laughing at this, but I'll bet 6 bundles of shingles would flatten it out while the adhesive set. Just a thought. I have a basement below and in my case that, and some screws from underneath is what I'm going to try. Dave


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## Goldtor64 (May 13, 2009)

*My repairs*

Well, I have finished cutting the hardwood and plywood subfloor away from the based board. It was wedge so tight that it was causing the baseboard to push away from the way at the top. I now need to put enough wait on it flatten it out, but not sure how to get the adhesive underneath that Dave E recommended. Otherwise, I will use concrete screws from the top. 

Any recommendations?


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## Goldtor64 (May 13, 2009)

Did either of you have success with the repairs. Jason, what type screws did you use?


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## Flt_Simulation (Feb 14, 2009)

I posted these photos before, but maybe someone can benefit again from it.

I had engineered wood plank flooring installed in my new house I am having built here in the Philippines. Moisture is a very very big problem in this country that resembles a steam bath.

The floors in the house are concrete. The only way they would install the wood flooring was to first lay a layer of thin poly foam sheeting ... This is to act as a moisture barrier. I believe having a moisture barrier between the cement slab and any wood above the cement is critical.

Here is what a roll of the moisture barrier they used in my house looks like:











Then they installed 10mm marine grade plywood over the poly sheeting. This photo shows the installer using a heavy drill with a masonary bit to drill through the plywood and into the cement below:











The next photo shows plastic anchors installed into the holes, then what looks like drywall screws are then hammered down. This gives the plywood surface a very tight fit to the concrete below (I think they spaced the screws about every 8 inches or so):











Then the planks are glued on there backside, and then stapled in the wood plank's tongue & groove area (with an air powered staple gun) to the plywood below:




















I just can't see where there will be any warping or buckleing of the hardwood planks after this install ... Certainly moisture from the cement slab should not pose a problem (I hope)


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## msv (Dec 4, 2009)

i keep hearing people laying plastic/foam barriers and then PIERCING it with nails/screws/anchors for attaching the plywood subfloor.... doesn't that kinda defeat the purpose of having a sealing layer between the slab and wood? 
just curious....


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