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Best way to flatten joists over a wide area, for flooring

Best way to flatten joists over a wide area, for flooring

Old 10-02-06, 12:00 AM
mcm is offline
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Join Date: Apr 2003
Location: El Dorado County, CA
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Best way to flatten joists over a wide area, for flooring

During a project to install hard wood flooring, I have needed to remove some subfloor panels due to water damage in some locations, as well as the need to plane down the underside joists such that the floor can be flat enough for the wood flooring.

I have quite a large area that needs to be "flattened", about 12x32 feet. I have tried to use a long level as a straight edge and plane down then measure repeatedly, but this is proving very difficult to get right. A good analogy I think is trying to give someone an even haircut with nail scissors.

I have had a thought to use a stretched string over two opposing points of the floor space, and take measurements from the string down to the joist every foot and make height map of adjustments, writing those down on the joists then breaking up the work into 1 foot sections that need 3/32, 2/32, 1/32" removed from the joists. I'm not sure if this is the best way to go about doing this, and it occurs to me that variation in joist height at room edges is going to be rather problematic.

Is anyone familiar with a good way to a) determine where thickness needs to be removed from the joists and b) procedurally perform the required work ?

FWIW some areas (in particular a ridge about 6 feet from one wall) are about 1/4" higher over a 4 foot span.
Old 10-03-06, 08:17 AM
Join Date: Feb 2002
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Use a laser level

Buy an inexpensive laser level (30-40 bucks at Sears).

Set the level up and measure from the laser line to the top of a joist that has the preferred finished level.

Mark the other joists for the amount that needs to be planed off and have fun planing.

You mention measurements of 1/32 and 2/32. If you get this close, you will never see this in the finished hardwood floor as the subfloor will hide this slight variation.

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