A subfloor is the foundation for your floor covering and plays an important role in the durability and longevity of your flooring. There are three main types of subfloors: wood planks, plywood and concrete.
The subfloor must be strong enough to support the weight of your floor covering, making it a factor in which material you choose. If your subfloor is inappropriate for the type of flooring you desire you can install a new subfloor, although this will add substantially to the cost of your home improvement project.
The layer between the subfloor and the flooring material is called the underlayment. Its purpose is to cover any imperfections in the subfloor and provide a smooth base for the flooring on top. Different types of flooring require different underlayment material.
While many people associate thick padding with improved softness, its primary use is to protect the carpet from impact. The proper padding will be determined by the type of carpet you choose and the amount of traffic in the room. Carpet manufacturers include padding guidelines in warranties and using the wrong padding can void your warranty. Carpet retailers and installers will take these warranties into consideration when assisting you with your padding choice.
Rebond: The most popular choice of padding, rebond is a high density bonded foam. One potential downside to rebond is that it contains a chemical compound that may cause yellowing in some carpets.
Foam: A medium density product, foam is recommended for low to medium traffic areas such as bedrooms. Because air can be trapped under the carpet, the carpet will bounce against the foam and can cause damage to the carpet's backing in high traffic areas such as living rooms.
Frothed Foam: This high density urethane foam is a good choice for high traffic areas.
Waffle Rubber: As with foam padding, trapped air can cause problems in high traffic areas.
Slab Rubber: Suitable for high traffic area, this single density product holds up better than waffle rubber.
Fiber: Mostly used for commercial and some berbers, fiber padding is a high-density nylon product made from scrap fiber.
Placed between the carpet and the padding, moisture barriers are intended to protect the padding from any moisture that leaks through the carpet, such as spilled drinks. Many carpets already have a plastic lining built in, making a separate moisture barrier unnecessary. Froth foam padding also has its own moisture barrier, so make sure to ask your retailer or installer before spending money on a moisture barrier product that you may not need.
Floating Wood and Laminate
Standard Foam: The most common choice of underlayment for wood and laminate floors is a thin layer of foam placed on top of the subfloor. This is a fine choice in dry areas, but in areas where moisture may be a factor you should add a moisture barrier (see information above) or select another option.
Combo: A standard foam underlayment with a moisture barrier attached, this is a good choice in areas prone to moisture.
Upgraded: A high quality foam made from a material such as rubber or fibers that provides some sound proofing between rooms.
Cork: An expensive choice, but appropriate where a high level of noise reduction between floors is desired. Contrary to popular belief, cork doesn't make the floors "softer" to walk on.
Nailed Down Wood
Plywood: This is by far the most preferred underlayment for nailed or stapled hardwood. If your subfloor is plywood, you can nail or staple the hardwood directly to the subfloor.
Rosin or Roofing Felt: These materials are used between the plywood and the hardwood as a sound deadener.
Using the proper underlayment for tile is critical, as it protects the tile and grout from cracking and falling apart. Imagine spending a tidy sum of money only to see it crumble a few months or years later. To avoid this disaster and safeguard your investment, make sure to select the proper underlayment.
Concrete Backerboard: A concrete core surrounded by fiberglass on both sides, this underlayment is water resistant, making it a good choice for kitchens and bathrooms.
Mortar Bed: Preferred by professional installers, this underlayment starts with a layer of roofing felt, followed by wire mesh and topped with mortar. Because it requires considerable skill to ensure the correct thickness and to level properly, this is not recommended for do-it-yourself enthusiasts.
Concrete Slab: Tile can be used over an existing concrete slab, but use a grinder and leveling compound to fill any holes and cracks and ensure a level surface.
Hardboard: Constructed of tightly packed wood fibers, this material provides a hard, smooth surface for vinyl flooring, although it should not be used in areas susceptible to moisture, such as bathrooms and basements.
Plywood: Probably the most popular choice for vinyl flooring, plywood is available in various grades.
This article highlights the importance of using the correct subfloor and underlayment for your floor covering and provides an overview of your choices. To make your final decision, please consult with your flooring retailer and/or professional installer, who will make recommendations based on your particular set of conditions and considerations. For a list of flooring retailers in your area, please click here. To find installers, please click here. For more information on how to choose a floor covering, please read our article How Do I Decide Which Floor Covering I Should Get?