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Old 01-03-2011, 08:23 PM   #1
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How to check a floor for flatness

Just wondering if there are any easy ways to check a floor to see if it's level enough for a tiling job (12x24's) I've seen a bunch of places talking about how important it is, but I haven't seen any places describing a way to check. I'm hoping there's some trick to using a laser level or something.

Thanks for the help.


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Old 01-03-2011, 08:27 PM   #2
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Flat and level are different things.


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Old 01-03-2011, 08:50 PM   #3
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The easy way is to measure the room and find the center point of the room and mark it with an X using masking tape. From this spot mark each quadrant into four squares, locate the centers and mark with an X. This will allow you to see changes in the floor throughout the room.
Now place the laser level in the middle of the room and level it. Shoot the laser on each wall and mark that spot with the pencil. This gives you a defined spot. Then move the level to each one of the other Xs and level it. Shoot the laser onto the wall. Mark that spot. Make sure this is done at 90 degree angles. You do not want to go onto the other marks.
When all walls are marked and you went to each quadrant you can now measure each pencil mark. This will allow you to see where each section of the floor is resting. It also tells you if you have settling issues. If you have areas that are more than an inch above or below another area, you will need to contact a contractor because there may be a problem with your foundation.
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Old 01-03-2011, 09:16 PM   #4
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There are two relatively fast, simple ways to measure a floor for LEVEL (not flat). The techniques depend on what equipment you have.

If you have a rotating laser level (I got one for less than $75 at a big box store), you set the level up in the middle of the room, and proceed to walk around the room with a tape or a graduated rod and make measurements. This will give you a direct way to measure how far out of level any given spot on the floor is. If you do not have a rotating level, you can use a standard builders level on a tripod with a rotating head to get the same result.

If you have a fluid level, or rent one, you can directly measure the elevation of any given spot in the room. Simply walk around, make the measurements, and plot them on a piece of graph paper.

Note that both of these techniques will tell you how far out of level a given spot is. The floor can be uniformly tilted (i.e. perfectly flat), but still be out of level, and these techniques would show an out of level floor (true), but without some math would not show that the floor was flat.
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Old 01-03-2011, 09:48 PM   #5
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It's important and good to know, but the tiles don't care if the floor is level or not. It only cares that it's flat.

Take a long straight edge and lay it on the floor in many areas. You will easily see if the floor has humps or valleys, usually both.

With 12x24" you want the floor to be within 1/8" in 10 ft. & 1/16" in 12" of plane.

TILE GUY - retired- TROY, MI - Method & Product suitability consulting.

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Old 01-03-2011, 10:52 PM   #6
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Go to Harbor freight and pick up a 6' level for $20.00
Flatness guidelines are 1/8" in 6' or 3/16" in 10'.

Or you can duct tape a 10' string to the floor , pull it tight , tape . it will also show you the contour of the floor .
move one end in a circle every 1' .


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