# How flat does a subfloor need to be for laminate?

My kitchen floor is dished. The middle of one interior wall was set on a pier without sufficient compaction. The settling was rapid, as the upper cabinets are set level, while the floor is 2 inches lower in the middle of one wall.

Imagine child's saucer sled writ large. It's 24 feet across and 2 inches deep. A support wall runs along the 24 foot dimension across the middle of the dish. So I have a dining room and a kitchen each dished toward the middle of one of the 24 foot walls.

The floor is smooth. If I use a 4 foot level at no point do I get a 1/8" gap. But it is not flat.

A 2" dish over 24 feet corresponds to a .35" sag on 10 feet or a .06" (1/16) on 4 feet.

Can I lay laminate on this?

Please do not say, "fix the house first" to do so would require shortening the support wall. Yes. The 2nd level floor is flat. Go figure.

That the upper cabinets on the lower wall are straight, makes me think that the bulk of the settling took very early, perhaps as early as during the completion of the decking on the bottom floor. Given the geometry for this to NOT be a support wall, then the floor above is cantilevered out 12 feet. (Half loft ceiling.) –

• If the bottom floor is dished and the upper floor is flat, it's likely because it's no longer resting on the support wall. 2" is way too much to deal with cosmetically. Unless you previously had a 2" hill on the upper floor, you should be able to correct the first floor support without shortening the wall. Commented Mar 5, 2018 at 5:54
• That the upper cabinets on the lower wall are straight, makes me think that the bulk of the settling took very early, perhaps as early as during the completion of the decking on the bottom floor. Given the geometry for this to NOT be a support wall, then the floor above is cantelevered out 12 feet. (Half loft ceiling.) Commented Mar 5, 2018 at 14:35