A good wood flooring installation begins with good subfloor preparation. A poorly installed subfloor will create costly and time consuming problems down the line, so don’t skimp on the time put into getting this step right.  A do it yourself subfloor preparation will take some time, but it is a fairly simple process.  This will help you to avoid squeaks, a loose floor, cupping, gapping and much more.

Before beginning, make sure you’ve gathered the necessary supplies.  Nothing slows a job down like six trips to the flooring store!

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The Robinson Hardwood professional flooring installation team at work preparing a subfloor.

Tools, Supplies for Subfloor Preparation:

  • circular saw
  • eye glasses or goggles
  • respirator
  • hearing protection
  • knee pads
  • gloves
  • crowbar
  • broom or vacuum
  • hammer
  • plywood or OSB
  • nail gun/nails or screw gun/screws
  • chalk line and chalk
  • 6-foot or longer straightedge
  • 15-pound asphalt felt paper
  • moisture meter
  • staple gun or hammer stapler
  • sander

Got it all?  Ok, let’s get started!

DIY Subfloor Steps

First, let’s get down to the subfloor as it is now.  Pull up the carpeting or current flooring.  If you have particle board as a layer, you will want to remove that too.  A top layer of particle board is a big no-no for all flooring except floating floors.

Next, let’s check the joists for spacing and direction. You want your joist to run perpendicular to your planking which should be no more than 19 inches apart.  If the distance between planking is more than 19″, you will need to brace between the joints.

After removing the carpeting, pad, tack strips and baseboards, you should have nothing but your subfloor showing.  Do a good job of cleaning up any debris, including old glue, off your subfloor.  Check for protruding nails and squeaks.  Install the new layer of subfloor perpendicular to the existing layer of subfloor.  Use chalk lines to mark on the new layer where the joists are positioned below.

Fasten down the new plywood, either with a nail or screw gun. Space fasteners every 6 inches along the panel ends and every 12 inches along intermediate supports.  Spacing between the panels should typically be about 1/8th of an inch.

You should now sand all the seams to ensure they connect smoothly.  Then check to make sure all the fasteners are secure and not sticking out in any way.

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The seams here have been fully sanded, the floor is swept clean, and the moisture barrier is ready to go down.

It is essential to check for flatness throughout the subfloor.  You can use either a level or a straight 2×4, moving it across the floor to make sure there are no gaps.  The floor doesn’t actually need to ‘level’, but it does need to be flat. Your floor should be flat to within 1/4 inch over 10 feet or 3/16 inch over 6 feet.

It is very important that you check the moisture level in the subfloor.  A damp subfloor may result in your hardwood flooring having buckles!  Take moisture readings at various places throughout the floor. You can record the moisture content and the date directly on the floor, but record it in your job log also.  Your flooring professional can help you determine the maximum moisture that should be in your subfloor before laying down your hardwood or laminate.  Check the manufacturer’s instructions for allowable moisture levels for the floor you’ll be laying.

Now it is time to put down the moisture barrier. Edges should overlap several inches so flooring won’t snag as it’s racked.  Staple the paper down.

As your last step in preparing your plywood subfloor, mark the joists again so the flooring installer can best plan how to install the hardwood or laminate.