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Sub-flooring installation tips when using hardwood flooring
06 May 2020

A successful flooring installation requires the use of a sound sub-floor system. Any mistakes in the sub-floor will obviously affect the installed floor and result in time consuming and expensive call backs. In order to avoid this, be sure to inspect the sub-flooring carefully and correct any problems before installing the finished flooring.

Sub-flooring moisture management – builder

OSB sub-flooring will adjust to new environmental conditions. Whenever possible, and before installing any sub-flooring, store the panels under cover on site. This will allow the panels to acclimatise to the current conditions. Always leave the required 1/8-inch gap between 4’ ends of sub-flooring panels to allow for expansion with changes in moisture conditions. The panels need to be glued as well as attached with the appropriate fasteners.

After the building is closed in, and the drywall and painting are completed, make sure to create occupancy conditions inside. This may mean switching on the central heating during colder months.

To provide the flooring installer with the best possible sub-floor here is a short check list:

  • Nail spacing (minimum 6”oc on edges and 12”oc in the field).
  • There should be a fastener ¾” from each panel corner.
  • Check that all metal hangers are fastened correctly (if not they may squeak).
  • Check that all the proper joist stiffeners are installed and fastened correctly (this will prevent bounce/deflection issues).
  • Ensure the sub-floor is clean, dry and flat.
  • Remember, it’s always cheaper to fix issues in the beginning of any process than at the end.

Moisture management – flooring installer

Prior to starting the hardwood installation, adjust your moisture meter accordingly and measure the moisture content of OSB sub-flooring by taking at least 20 moisture readings per 1,000 square feet. Compare that to the moisture content of the hardwood and follow the guidelines for the acceptable percentage difference between sub-floor and the hardwood flooring being installed.

In areas where moisture is or may be a concern, consider installing a vapour control layer over OSB sub-flooring panels. This will minimise moisture transfer and the impact of any seasonal humidity changes. Install vapour control layers with a good tear resistance to protect from any rips that may occur from reversals of wind pressure.

Inspecting the sub-flooring – flooring installer

Check that the sub-floor is stable because hardwood installation alone will not stabilise a floor. Check all the items listed above and make sure that the fasteners are not under or over driven.  Sand or fill all uneven joints or areas that may cause issues with the finished flooring. Always follow the flooring manufacturer’s guidelines for sub-flooring, hardwood flooring and adhesive installation. The finished flooring manufacturer knows the best way to install their product because species, widths and styles all have an impact on installation.

For further information, call 01786 812 921.

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