I've got prefinished engineered hardwood oak installed in new construction that was nailed down. I immediately noticed numerous areas where the floor is uneven. There are high spots that I first noticed when walking on them and then found more spots when putting in furniture that rocked on the uneven floor. I could move the furniture around and it would rock in some places but not all so it wasn't the furniture. The GC finally had the floor installer out along with a subfloor rep (he was trying to say it had to be the subfloor delaminating. They pulled up the floor in 1 spot. There was no delamination but there was a high spot on the subfloor joint. He scrapped that down so it was flat and reinstalled the floor. It lays flat there now. We also had a flooring inspector in. He measured all of the moisture content and found everything to be fine. He believes the subfloor was not prepped correctly.
The proposed remedy is to come in and pull up the floor where it's uneven, scrape the subfloor flat and then glue down new boards. I do have a fairly thick wear layer compared to most engineered wood but there isn't near enough to sand the high spots out.
Is it reasonable to just pull up affected areas? I don't have a good estimate yet of the percent of the floor to be pulled up yet but I plan on going through the whole house with a level to insure every bad area is identified. I only want to do this once.
They (GC and floor installer) originally tried to say it was within the spec of 1/8" in 6' or 3/16" in 10'. My problem wasn't a slope over 6 or 10' but high spots that are well under 1'. They do at least concede now that they are out of spec in some area but I don't want to get in an argument with them on which spots warrant fixing. Is there any kind of specs to cover a much shorter spans then 6 or 10'?
Is it ok to mix in a lot of patched wood that is glued down with nailed hardwood? At about what percent should they rip up the whole floor in a room and nail everything down?
Is there anything else I should ask them or look for?

Thanks,

I've got some pictures that I'll try to add showing some measurements of bad areas.

The subfloor joint that you refer to would be over the floor joist. Assuming the joists are 2 X lumber the joists are probably crowned. When joists are installed the crown would be on top. Who ever installed the oak hardwood should have prepped the subfloor properly to mitigate these high spots. Assuming the joists are 16 inches on center these high spots should be found at multiples of 16 inches. If it were my house I would want the entire hardwood floor taken up, the subfloor properly prepped, and new hardwood installed per the manufacturer's installation instructions. I would not let them sand the hardwood to correct this problem.....the factory finish is better than a site applied finish. The high spots would have been very noticeable to the hardwood installer.....generally the subcontractors working on new homes don't get paid a lot so in order to make $ they have to work fast which means they don't always take time to do things right......guess who winds up paying for the shoddy work.

Thanks, The first floor is over 2 x 10 joists. The second floor is over open web trusses. I've got the problem on both floors. Sanding is not an option since the variation is too much.

Before agreeing to any type of patch/glue repair I would contact the flooring manufacturer and inquire whether this approach is legit as far as they are concerned. It may also create a manufacturer's warranty issue.

Having worked in a plywood mill and laying floors for some time I have noticed that some plywood is slightly thicker than other areas and this difference can be noticed where the plywood butts against another panel The plywood is tested for average strength by a testing company but thickness as it is installed can make the joints uneven. gluing down new wood where the sub-floor has been flattened will not affect the longevity of the floor. Since it is pre-finished and can be done so that you can not tell where the work is done, I would go with what the installer volunteers to do.

I now need help understanding the floor spec. I am reading the 1/8" in 6' spec as if I have to raise one end of the level more then 1/8" to get a level reading on my 6' level, it is out of spec. My GC says that if he puts a 6' straight edge on the floor and he can't measure a gap of more then 1/8" at any point under it, it's within spec. He didn't have an answer for at what point a slope on the floor is unacceptable. It just has to be flat to be acceptable to him. I've got a large section on my first floor that I've identified with greater then 1/8" slope in 6' thanks to my grandson rolling balls on the floor that made it really easy to identify the bad spots. My GC says it's because of the crown of the joists and there isn't much he can do about it. He also says it will flatten out some over time. I'm not sure I agree with him. I believe a steel beam is under the high spots and not the center crown of the joists. I also would have thought they should have taken care of any excessive crown before applying the subfloor.
How long should it take for the floor crown to reach equilibrium?
I still have numerous spots where there are high spots from likely poor prep of the subfloor. In general he seems to be willing to address those spots but we will see when he gets his flooring subcontractor in here and see what push back there is then. I'm assuming he's making the subcontractor eat the cost of fixing those spots.
Thanks for the previous feedback.

Does the steel beam run down the center of the house? If so, do the joists rest on them or are they attached to the sides? As far as hardwood flooring is concerned flat and level are different. Hardwood is affected by flatness....as you have found out. If the floors aren't level that is a different issue and should not affect a flat floor.....but the GC should be concerned with the framing sub's sloping floors. Unfortunately GC's can be at the mercy of their subs. Should be an interesting conversation between the GC and the sub. The framers should have paid more attention to the degree that the joists are crowned.

I went under the house and verified that there is a steel beam running under the high line that slopes down on both sides at greater then 1/8" per 6'. The joists are resting on the beam. So the slope has nothing to do with the joist crown as the GC has claimed.
I still need to understand what is acceptable. Is it less then a 1/8" slope over 6' (or 3/16" over 10') or is it no more then a 1/8" gap under a 6' straight edge. I believe it is the first.
Thanks,

Sometimes the framer causes the problem and the next person just does the best he can with it. This is where the next person in line needs to call a halt so the problem can be recognized and a solution determined. This is why a floor needs to be checked before the floor is laid. If the floor joists meet at the beam, there is a chance for the crowning to occur right over the beam if it is out of plain. The easiest solution would be to shorten the supports for the beam.

Are the high spots just in the vicinity of the steel beam or are there some in other areas of the floor that would be caused by some joists being higher than others? Do the floor boards run parallel to the steel beam and perpendicular to the joists?

I've got high spots that appear to be poor subfloor prep. In investigating those spots I've discovered the section that slopes down in both directions from a steel beam. The hardwood floor runs perpendicular to the beam and parallel to the joists.
I'm still trying to understand how to apply the "less then 1/8" in 6' or less then 3/16" in 10'" spec. My GC is reluctant to address the issue and is interpreting the spec different then I believe it should be.

This is an excerpt from the National Wood Flooring Association guideline:
1. For installations using mechanical fasteners of 1 1/2” and longer, the subfloor should be flat to within ¼” in 10 feet or 3/16” in 6 feet.
2. For glue-down installations and installations using mechanical fasteners of less than 1 1/2”, the subfloor should be flat to within 3/16” in 10 feet or 1/8” in 6 feet.
Do you want to check it? Get a long (6 foot) level or a shorter level and a straight board. Put one end on a high spot, rotate the level and check the gap from the bottom of the level to the surface of the floor. If any of the gaps are greater than the tolerance for the distance ( 6 or 10 feet) and fastener length then it is out of spec. It's probably not totally accurate to do this on the finished floor as some of the boards may not conform to the subfloor. But if boards were installed parallel to the joists the low spots may be more pronounced.
Do the high spots seem to be on the joists with valleys between the joists?
GC can blame whoever he wants i.e. flooring guy or framer but they work for him. Did the inspector give you a written report?

Just out of curiosity who decided which direction to lay the flooring?

I do have a report from the inspector. The key part is it ncluded below. My issues with the report is the inspector only looked at spots I had pointed out and I had not done an extensive inspection of the floor for trouble spots. I had only identified spots I had noticed walking around or where furniture rocked. Neither the inspector nor I had looked under any of the other furniture (like beds) or rugs so it wasn't a comprehensive inspection. I also hadn't noticed the sloping floor until my grandson was rolling balls on the floor after the inspector had been there. He had not applied a level (just a straight edge) to anything on the first floor which is where the slope is. The GC had hired the inspector so I haven't talked directly with him except when he was there for the inspection and he wouldn't comment on what he found then.

It was either the GC or flooring subcon that picked the floor direction. To me, that doesn't seem to be the problem. Most of the high spots seem to be very localized. I can put a 2' level on then and get a lot of rocking (usually at a flooring joint) but when you put a 6' level on them it just shows a problem at that spot. I do have spots where I can go down the long joint and get rocking along 3 - 4 feet. This is causing very annoying rocking in some chairs and tables as well as noticeable spots when walking barefoot.

What is the spec for the slope of the floor?

The inspectors criteria of unevenness visible from a standing position seems very subjective and therefore a very poor criteria. There are too many variables like lighting, finish, observers height and observers subjective criteria for what is "visible".


From the report:
Observations:-The Engineered prefinished Oak 1/2" x 3 1/4" is installed over a wood subfloor, red rosin paper isunderlayment used and boards are nailed into the subfloor.-The floor has raised boards visible in the kitchen, in the living room, second floor hall and onebedroom. The unevenness is visible from a standing position. Seven other areas pointed out werenot visible from a standing position and 5 feet up and 2 feet away.-Boards were removed from second floor hall and the unevenness in subfloor was corrected.Boards need to be replaced and secured.

Applicable Field Tests:-Moisture readings were recorded using a Ligno non-invasive meter with a range of 0 to 30percent. Moisture readings of installed boards recorded at inspection ranged 7.3 to 8.8 percent.These readings are in the normal range.-A six foot straight edge was used with a ruler to measure flatness. The four affected areas whereboards were raised measured 3/16" in six foot radius. This is not within the installationrequirement of 1/8" in six foot radius.-A magnet was used to locate fasteners and the spacing measured with a tape measure. Thespacing measures 1 to 3 inches from ends and 6 to 9 inch spacing of fasteners.-There was no measurable vertical deflection when floor was walked on.-Hygrometer readings recorded at inspection read 43% relative humidity.

When you say rocking at joints do you mean joists? Does your flooring manufacturer's instructions say anything about a vapor retarder between the subfloor and finished floor? Not for anything but red rosin paper is not a vapor retarder. Don't know that there is a spec for level unless it affects flatness. Boards are perpendicular to the steel beam...does a level placed along a floor board rock over the steel beam hump? Just curious about the flooring direction as its direction may or may not make flatness and slope issues more or less noticeable. Inspector may be trying to determine whether the flooring installer or framer is at fault. I'm still trying to get a clear picture as to whether the high spots are over the floor joists?