We want to install laminate flooring in our family room, and had someone out to measure the room and bid on the job. He claims that there's a hump in the floor that makes it impractical to install Pergo.

He did this by sight and didn't use any tools. We can't see a hump. We didn't consider him reliable (and had to ask him to leave the house after a few minutes; he was argumentative).

How can we tell before ripping up the carpet if the floor is level enough for the flooring we want? The house was built in 1986. This room has a wood subfloor, and is over a basement. There are no poles, beams, or supports beneath this room -- no obvious cause of a hump.

  • You will need to remove the carpet and padding to really know. You can either get a laser pointer to check or get a 6' level and use it. Either should tell you. You can also stretch a string from corner to corner to know. Put a nail in each corner. Tie the string to one. Push the knot to the floor. Go to the next nail, 2 wraps around nail. Pull snug. Push to floor. Tie. and then check for gaps under the string. Commented Sep 6, 2018 at 14:28

2 Answers 2

  • Lie down and eyeball it. It's easier to see if you are right down on the surface. Someone in the business of laying floors might have developed a better eye than you (if they miss it, it costs them money) and not need to lie down.
  • Shoot a laser pointer across the floor - either skim the surface looking for discontinuities, or lay it on the floor and check its height with a ruler as it goes across the room. Easier if you can get the start and end adjusted to the same height. A hump will be a place where the beam height above the floor reduces; &/or where the beam won't make it across the whole room if it's right down at floor level.
  • Choose a long straight board, and set it on edge on the floor. If you find a place where it rocks from end to end, that's a hump. Check that the board is really straight by making sure it rocks about the same on both edges (a warped board will rock on one edge, not on the other - a straight board on a hump will rock on both edges)

If you want to install a wood floor over a hump, wood parquet can be much more forgiving. I don't know if the laminate folks have entered that market, but it can be quite affordable in real wood.

  • I had laminate laid on my first floor, the hump in there was quite high. the flooring is ridged enough to span over humps in the floor if they are too high, in my case, the rule was 1/8" using a 3 ft straight edge. Self leveling underlayment was used to fix the worst spots. Any higher and the floor will not lay tight to the floor and after time, foot traffic will fatigue the MDF core and cause the lap joints to break and fail.
    – Jack
    Commented Dec 27, 2013 at 4:37

With carpet and pad underneath it - especially worn carpet - I don't think you can determine whether the floor is level enough for laminate.

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