Need Advice, Cupped Floor

[john lawson]

My wife and I built a new house last year. The oak hardwood floor was installed this past winter. We are ready to have the last coat of poly put on the floor, but it has developed a cup or warp in the last couple of months.

Attached are some pictures of the cup, and yes, it really looks this way. I need some advice. My first reaction is to have it sanded flat and refinished.

Any other ideas or advice?

thanks

john lawson

[Neal Clayton]

yeah, because no one uses dried lumber anymore. used to be just lowes and home depot 2x4s, now it's everything.

your floor joists have dried over the past few months, they were green when the builder built it. now your air conditioner is drying them out. that's causing your floor to compress and buckle. don't be surprised when the same thing happens on the walls leaving you with visible drywall joints.

[john lawson]

Neal, the joist were installed over a year ago, the floor about three months ago so I don't know if that is the problem or not. It seems that the floor is compressing with humidity since the heat from the furnace has been off. Anyway, the floor seems to be compressing on itself and lifting at the seams.

The question is, what do I do now, if anything?

thanks

john

[Matt Ocel]

John -
Did "you" build the house or did you have it built.

If you had it built call the builder.

Find out what caused it to cup, there had to be or has to be a moisture source.

Last resort - resand.

But you might run the risk of it then becoming convex.

[Neal Clayton]

it's one or the other, either you've got water coming in or going out.

got a moisture meter? i'd pull one up and check it and the joist underneath to find out which is responsible.

[Sean Kinn]

A few more details of the install may help.

1. How long was flooring acclimated in room before install.
2. Was room heated or cooled at time of install?...I'm guessing heated since you mentioned winter.
3. What is the subsurface? concrete, plywood, OSB?
4. If this is above a basement, was a vapor barrier such as roofing paper installed under the flooring? If it is, is the basement heated/cooled sa well?

[Dale Lesak]

One other question that I didn't see asked. How are you cleaning the floor? Being a old roller rink operator. have seen this happen when they use too much water on the floor for cleaning. the water gets between the boards and into the side grain. Fix= letting it dry out for a long time. a lot of the cup goes away.

[Peter Quinn]

Looks like some nice flooring. 5"? 6"? Hard to get a perspective, but definitely not 2 1/4" strip flooring. I'd figure anything over 3" wide is going to move seasonally, maybe not so much that you'd stub a toe but never perfectly flat unless you go quarter sawn. I can see the scalloped effect in your pictures with all those windows (nice view) but can't tell how bad it is.

If the problem is severe, the problem is moisture affecting each side of the board differently. If I'm looking at this right the edges are cupping up? Flat sawn flooring is usually milled heart wood up, sap wood down in most cases. If a board is wet and left to dry with air circulation it will cup toward the sap wood, or down in the case of flooring, which is preferred. In your case this would result in the boards having a crown, not a valley.

If the flooring was dry and is taking on moisture from below, the B face (sap wood) would swell and cause this kind of cupping. Or, if the floor went in a bit wet the exposed face might dry more then the side facing the subfloor, causing this kind of cupping. If the space were heated all winter and the wood had excessive moisture or the wood was not properly acclimated to its environment you would have the conditions for this type of cupping and it may not be done moving. If this is on a new slab on grad without a moisture barrier you could easily get this kind of cupping and expect more.

Did you put it in? Need more info, because it may continue moving, so sanding may be futile.

[Peter Quinn]

Just re read the other posts. I really doubt the joists are an issue here. ALL joist material goes in green, which for framing means around 24%, but fir and yellow pine both air dry very quickly, typically with in 6 months. They don't make KD joists to my knowledge.

And in any event joists are oriented grain wise such that they would not create this type of systemic cupping. Plus the sub floor provides considerable sheer strength and is typically a stable engineered material (plywood or OSB) You might get a random screw pop in drywall, which has considerably less strength and fewer fasteners than oak flooring, but the whole house will not buckle crack.

Your problem is within the upper layers of the floor system. Not the framing.

[Ron Williams]

It appears that when the floor was sanded the floor had a greater moister content on the face side. I assume that the heat was on this winter and dried the floor causing the raised joints. Controlling the moisture in a house is very difficult to do but very important. Shoot for between 40-50% relative. Is this house built near a lake?

[John Keeton]

I agree with Peter on the joists. I don't see how that could be an issue.

I think Sean has hit on the answer. From the view, it looks like this is a second floor. I am betting on an unfinished, not very well conditioned, basement, that has some humidity. The upstairs is probably air conditioned and remains at a 40% or less relative humidity. The bottom of the boards are keeping a much higher moisture content. I have 5" oak over a walk out basement, but it is finished and conditioned. We also used felt paper overlapped as an underlayment.

We have not had any cupping, although we were told it was a possibility with wider flooring. Some of the other suggestions could be contributing factors as well, sunlight (heat) drying the top, etc.

[john lawson]

I'll see if I can answer most of the questions asked:

Is it near a lake? Yes it is on a lake, about 40 feet from the water.
Is the flooring over a basement? Yes, it is
When was it installed? In the winter, with the heat on.
Was the flooring allowed to acclimatize in the house? Yes, about 4 weeks
Was there an underlayment? Yes, and the there is also insulation between the basement and the first floor.

I watched the flooring guys put it down. They seemed to do a good job. The wood itself is beautiful, 4" wide red oak. Hardly a knot anywhere.

The question is, what would you do now, sand it? Not sand it? What will it look like if I do have it sanded, or not sanded?

What would you do at this point?

thanks

[John Keeton]

Given your responses, I would do nothing for a year or so and see what happens. Sanding and refinishing can be done later as well as now, and if the wood was installed with a high moisture content, it is possible that it may lay down somewhat. Would hate to see it sanded and then start to lose the cupping, resulting in the reverse problem mentioned previously.

[Steve Schoene]

What does the flooring installation company say?

They have installed a floor that has become defective in 6 months, and unless there was some unusual condition that they couldn't have been expected to anticipate they ought to provide the solution.

[Matt Ocel]

John -
With humid summer weather coming, I would wait until the dead of winter to sand again. See if you can get moisture level down to 3 to 5 %.

out of couriosity - Was the basement floor poured at time of install?
I'm dyeing to find out the source of moisture.

and

I would try to hold installers liable. (my .02)

[Matt Hutchinson]

Even though the boards were setting in the house for 4 weeks, if they were still in bundles/stacks the inner boards may not have adjusted properly. As a result, they probably weren't installed stabilized. With the underside being locked against a moisture barrier and the topside finished, any moisture in the boards would take a long time to evaporate from the underside. Conversely, the topside, even though finished, lost the moisture much faster, resulting in the cupped flooring. This is my best guess.

Time may help to reverse the cupping, but I couldn't say for sure (hopefully it will). I have seen older homes with cuuped floor, and they had been that way for decades. Also, I think you should talk to the seller of the material, not just the installers. I am wondering if they sold it with higher than normal moisture content. Was this bargain priced flooring?

Hutch

[john lawson]

The floor was put down well after the concrete basement was poured, at least a year afterward.

The other thing that has me puzzled is the idea of too much moisture being the problem when the floor was installed. I assumed, and still tend to believe, that the issue was less moisture when installed, and more moisture now, several months after installation. The reason I believe that is the boards are being forced up, and the seams are non-existent. If I am correct they will tend to open up again during the winter, with the heat on, and the boards will lay somewhat flatter. But, if I am correct in that assumption, the edges will be bent and not lay flat, and the seams will open up showing a gap.

The flooring company does not know about the problem yet. The floor has two coats of poly and is due a third coat in the next few weeks. I am going to address the problem with them at that time. However, they will not have any liability as I provided them with the wood, (bought it out of state and had it shipped in). I checked the moisture content with a meter before installation, and it was less than 10%. I thought I had covered my bases pretty well before they started installation.

I am willing to pay them to sand it again, if that is the issue, I just don't want to make a mistake in the remedy and make the problem worse, or miss something obvious as far as a solution. I figured with all the woodworkers on this site that someone had run across the problem and say, "oh yeah, here is the problem and here is what you do to fix it"

So far the solution seems to be wait a year and sand it. Of course, the problem with that is we move in, have an ugly floor for a year, make a heck of a mess when it is re-sanded and hope that fixes it. Not a very appealing course of action.

Any other comments, suggestions.

thanks

john

[Matt Ocel]

John -

Couple of silly Q's

Do you grow any plants in the basement?

Do you have any aquariums in the basement?

Do you have a sump pump and does it run constantly?

Is you ice maker line leaking where it attatches to the fridge?

Sink leaking?

Dishwasher leaking?

The leak only needs to be a little drip and over time can creep under the wood across the room.

[Peter Quinn]

I will reiterate that plain sawn flooring is generally milled heart wood up, and this is important to remember as you diagnose your problem.


If the relative humidity in the house was very low during the winter, and the entire thickness of each board dried considerably, it should cup down, toward the sap wood side during heating season. As wet plain sawn flooring dries thoroughly it will cup down, not up. Look at ANY flat sawn board you can find in the open air. It will ALWAYS cup toward the sap side (out side of the tree, longer growth rings, more shrinkage) as it dries.

If for some reason the face of the board were drying much faster than the back it could cup up. Flooring is only 3/4" thick and shouldn't take that long to reach equilibrium, so I doubt this condition would persist into the summer.

Take a flat 3/4" plain sawn board and moisten both sides with a sponge. It will ALWAYS cup toward the HEART wood side if moisture is added, because the longer growth rings on the out side of the tree expand more than those on the in side. Wood movement is annoying but not random.

So if the boards were in fact installed dry in the winter, nailed tightly together, and took on moisture as humidity rose in the spring your type of cupping could exist. Question is will they dry again in the winter and move the other direction or lay flat? If the humidity in your structure regularly swings by 30% points seasonally I think your in for a lot of problems with that oak. Red oak absorbs and looses moisture quite readily. Forced hot air is brutal on millwork. They make whole house humidifiers based on a steam generator that operates via the duct work in conjunction with a humidistat to keep the relative humidity at acceptable levels during the winter. This might be a consideration in your case.

My father was complaining of nasal problems and doors that wouldn't stay shut in the winter. I got him a digital hygrometer and his house with typical gerbil wheel humidifier in the HVAC plenum was 18% in the winter! That is too much to low. The pine doors shrunk so far that they wouldn't meet the catches any more. His pergo, however, did not move.

Flooring is made with a back bevel on either the tongue or the groove edge depending on the manufacturer. By design it takes a considerable change in moisture content before gaps on the face will become apparent. It is dreadful to have flooring refinished in a home in which you are presently living. This I understand. But I would consider waiting, getting a good hygrometer or two placed about the house, and monitoring the relative humidity levels seasonally. What you want is wood in equilibrium before you sand again, and this is difficult to achieve if your HVAC system is misbehaving.

Your humidity should stay between something like 38%-55% in temperate climates in controlled space. I'm not an expert on HVAC, so check with a good mechanical contractor for specifics on this. Your heating system may be fighting with your flooring system.

Another option is to learn to like it! The hard pine floors my 100+ year old bungalow are nailed to 12" diagonal pine sub floor over an unheated often moist basement. My floors dance seasonally, but I enjoy the character it provides.

I hope this helps in some way.

[john lawson]

Thanks for all the replies and suggestions.

Matt, as to the questions about leakage or anything going on in the basement, the answer is no. We don't have all our plumbing hooked up yet, no ice maker, nothing wet in the basement, dry as a bone.

Peter, as to the cause, I am leaning toward your explanation of being dry in the winter and then taking on moisture in the spring.

I just don't know what to do about the problem. I am working on a fairly short time line to get things done to finish up, and this is just another in a long list of delays. (You've heard this before, I am sure)

thanks again guys.

john lawson

[Matt Ocel]

Close everything up, fire up the AC and run a dehumidifier for about a week.

See if that makes a difference.

[Matt Ocel]

John -
A question I forgot to ask.

I noticed your from AL.

I not familliar with your local weather conditions and you said that you first noticed the cupping a couple months ago, did the cupping start at about the same time your relative humidity went up?

[Tom VanPay]

How much of a gap did they leave around the perimeter when they installed the floor? There should have been 1/2" to 3/4" .

[Greg Sznajdruk]

I'm a retired Restoration Contractor (Insurance claims); during my career I’ve probably dried a couple hundred-hardwood floors.

DO NOT SAND THIS FLOOR WHILE IT IS CUPPED. The cupping (concave in cross section) is caused by moisture you must determine where this moisture is coming from. Sanding while the floor is cupped will temporarily give you a flat floor, when the wood dries you will then have the reverse problem the flooring will be convex in cross section.

You could consult a Restoration Contractor in your area that has the equipment to dry hardwood floors, but more important has the metering tools to asses what the moisture content of the wood is presently. Potentially where the moisture is coming from.

The IICRC web site can provide a Certified Contractor in your area.

If you are curious as to how hard wood floors are dried as a result flooding we used a system called Injectidry. This mat and vacuum system along with Desiccant dehumidifiers can dry a hardwood floor to its pre-loss condition.

Greg
IICRC Certified Master Restoration Technician
Hardwood Floor Dryinghttp://www.steammaster.com/services/emerg/drying/wood-floor-injec_thumb.jpg (http://javascript<b></b>:MM_openBrWindow('drying/wood-floor-injec_normal.jpg','popimage','scrollbars=yes,resiz able=yes,width=490,height=370');)
Injectidry

[Pat Germain]

Sorry to hear that beautiful floor is cupping, John. Coincidentally, I'm about to start a hardwood flooring installation at my house. I've been doing some online research and came upon an example of your exact situation. You can see it here:

http://www.hardwoodinstaller.com/hardwoodinstaller/installers.htm

In that example, the wood flooring had a high moisture content when it was installed. Perhaps your problem is similar. Even if you let the wood acclimate, if it was stored in an area with high humidity, it may not have dried properly.

Unfortunately, neither I nor that web site has a suggestion as to how to fix the cupping. I would go with the previous suggestion of waiting it out. I would also try to find an experienced flooring installer who would likely have some suggestions.

FYI, that web site recommends asking any flooring installer a very important question: "What type of moisture meter do you use?" If he can't answer, find one who can. I'm wondering if whomever installed John's flooring checked it with a moisture meter before starting the job. If he did, that may suggest the flooring absorbed moisture on the bottom side after installation.

[Greg Robbins]

I'm wondering if the insulation between the basement and the first floor might be causing the problem. If no air can circulate under the floor it could cause more moisture to be held under the floor and may cause the cupping. :confused:

[Brad Shipton]

I agree with Greg. Do not SAND until you figure out what is the problem. Right now there are many locations where the boards will not be touching the subfloor and if/when they dry, if you sand you could end up with the reverse problem. Have you measured the degree of cupping? This is a tough floor not to see some cupping with the amount of windows you have. Two other things would be to cut out a small piece somewhere so you can test both the subfloor and the hardwood with a moisture meter at that location or you might want to layout some furniture to see how it all looks when it is occupied and there are items to block the glare effect that is so evident in the pictures.

Out of state wood supplier. Looks like great stock given the lack of knots, board widths and lengths supplied. I assume this is a top rate manufacturer that does comply with the correct specs? I ask only because it seems you have done about everything you can to avoid this problem.

The floors were flat after the installers were done, right? The glare would have become far more evident after finishing especially if you used a gloss v. satin. Which floor finish did you use? Was there a time lapse between the install and when you started finishing the floor or did you start immediately after? Only reason I ask, is if there was a time lapse and the floor was flat when they were done installing the finish maybe the problem could be somehow related to the finish procedure.

As to the sanding in place. Piece of cake and will not make a mess so long as you find a contractor with a good DC on his machines. With the degree of cupping you can probably get away without using a belt sander. Seems to be fewer DC setups with those. Bona does have one. I used a Varathane sander to do mine in place and I set my Dylos in the room as i was doing it and the reading never exceeded 1500. This machine is essentially three 7" random orbital sanders with a big mass over to speed up the process. There was hardly no dust on the walls when I was done. Yes, it sucks to move furniture and it takes time, but it is not that bad. The downside of the typical rental type sanders is they are a lot slower than the heavy duty belt sanders, but you are not dealing with anything like some of the old floors pro's deal with.

Brad

[Russ Sears]

I'm watching this with interest because I don't know much about flooring. Is the floor absorbing moisture from the bottom and not the top due to the finish on the top?