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Quick Bit About Subfloors

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Quick Bit About Subfloors
March 8, 2017

Quick Bit About Subfloors

Guest Post from my Friend Alan…

Throughout the years I have spent in contracting, and having experience with several different flooring contractors on my projects, there is one common thing on which we all agreed. No matter what type of flooring you have and how professional the installation may be, it is only as good as the subflooring underneath. Preparing the subfloor in the correct manner to start with, will save you time and money in the long run. Of course it would be very disappointing to have all the work finished on your project including your dream floors, only to become aware of an issue or imperfection with the flooring, caused by a subflooring issue. There are couple common type of subflooring materials that we will look at to help you to see if the subflooring you are using is appropriate for the situation.

Plywood and OSB (oriented strand board) subflooring over floor joists is a normal find in newer homes and new construction. This is a very common subfloor for home with crawl spaces. With the proper installation, it is suitable for almost any type of flooring. It is especially a great subfloor to use under wood flooring because of its properties. These subfloors are usually ¾” thick and are found in 4’x8’ sheets which cover 32’ square feet. A better quality plywood or OSB subflooring material will have a tongue and groove joint that will help the subfloor join together for a very strong and stable subfloor. It is best to install this type of subflooring over 16” on center floor joists. Any wider spacing of the joists will make the subfloor week and bouncy. Be sure install the flooring with the correct fasteners that the manufacturer recommends.

If you use plywood or OSB for a subfloor, you might need to take a look at the need for a vapor barrier as well, before you begin your flooring project. There are a few types of vapor barriers you may want to research at your local building store or home improvement retailer, or inquire with your contractor. A vapor barrier may be used in some areas of the country to prevent moisture and air from entering the home through the subfloor. Much of the laminated flooring of today is installed over a vapor barrier, and this layer is also a good source of insulation. If a wood floor is to be installed over the plywood and OSB floor, a layer on construction felt is often used to help seal the wooden floor to prevent moisture from entering the home.Many types of flooring may sweat and absorb moisture if the proper moisture barrier is not installed, but check first with local codes and situations.

One common subfloor that is used over the plywood is a Masonite underlayment. This is generally available in sheets which are ¼” thick and comes in convenient 4’x4’ squares. These sheets are glued and nailed over the plywood or OSB and provide a very smooth working surface, necessary for many types of vinyl flooring. The seams become practically unnoticeable.

No matter what type of flooring you will be using in your project, you will need to make absolutely sure that the proper subflooring is selected and installed correctly. If you have any questions as to what type of subflooring to use, it is best for you contact your local contractor or building professional.