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)