Wood Floor Installation Methods Vary
November 29, 2007
When most people think about installing wood floors, they typically envision a hammer, nails and a lot of back-breaking work. The reality, however, is that there are several options available for installing wood floors, and choosing which is the most appropriate method will depend on the type of flooring being used, whether the floor will be installed above or below grade, and the type of material being used for the subfloor. Basically, there are three methods commonly used to install wood floors: nail down, glue down and floating.
Nail DownNailing down wood floors is the most common installation method. The process involves nailing or stapling the wood flooring material directly to a wood subfloor. Typically, the flooring is installed by blind nailing the material through the tongue of the floor boards, into the wooden subfloor. In this way, the nails are not visible after the flooring is installed. In most cases, as the material fills the room, it will be necessary to face nail the last few boards as the nail gun or staple gun cannot accommodate the last few rows of material. This installation method works for both solid and engineered wood flooring material, but only for wood subfloors.
When nailing down a wood floor, it is important to following nailing schedules to ensure a quality installation. The National Wood Flooring Association Hardwood Flooring Installation Guidelines recommends fasteners be spaced eight to ten inches apart for solid strip and plank flooring, and four to eight inches apart for engineered strip and plank flooring. Using fewer fasteners than recommended could result in cracks or squeaks in the floor, while using more fasteners than recommended could result in splitting the tongue.
Glue DownThe glue down installation method involves using adhesive to adhere the flooring material directly to the subfloor, or to a moisture barrier installed directly on the subfloor. The adhesives work by creating a bond between the subfloor and the wood flooring through a chemical reaction process. While all adhesives work on the same principle of changing chemically from a viscose liquid to a solid, they differ in the carrying agents or catalysts that activate them based on the chemical properties of the adhesive.
There are three types of wood flooring adhesives available on the market today. They include water-based adhesives, solvent-based adhesives, and moisture-curing urethane adhesives. Because each of these types has different application and performance characteristics, you will need to do your research to find the product that will best fit your installation needs. Some considerations that will have an impact upon which adhesive you ultimately choose for your installation are ease of product use, product performance span, and VOC regulations in your state or in the area where the installation will take place.
Before beginning a glue down floor installation, it is important to make sure that the subfloor material is dry and level. If you find any high spots or low spots, you will need to make them level before installation begins to ensure the long-term performance of the floor.
As a general rule, you only want to put down about as much adhesive as you can effectively work with in a 15 to 20 minute period of time. Any longer than that may cause the installation to fail as the bonding reaction may already have begun before the wood is installed over the adhesive. With many adhesives, the adhesive material must be down on the subfloor for a specified period of time before the wood is placed on it. This is called flash time, and it is important to allow a proper amount of flash time to achieve optimal performance. Other adhesives do not require any flash time and are called wet lay products. These adhesives require that the wood be installed immediately after the adhesive is put down, so it is important to know and understand the flash time requirements for the product you will be using.
The properties of each type of adhesive vary significantly among manufacturers, so you should always check the manufacturer’s recommendations before any installation begins. Always follow the wood flooring manufacturer’s recommendation for the adhesive to be used to install the product, and the adhesive manufacturer’s recommendation for the trowel to be used to spread the adhesive. Other factors, such as relative humidity, could influence the bonding properties of the adhesive being used as well, so you want to be sure that the job site is at ideal conditions before beginning the installation.
FloatingThe final wood flooring installation method is floating, a process that was created by a wood flooring manufacturer in Sweden more than 60 years ago. Using this installation method, the flooring material is neither nailed nor glued to the subfloor, but floated above it. The flooring material, usually engineered, is either glued or clipped to itself, both tongue to groove, and at end joints. This gives the floor stability, without actually fastening it to the subfloor material beneath it. This type of installation is ideal over existing flooring material, such as vinyl, ceramic or laminates which can be difficult to remove.
Before beginning a floating floor installation, it is important to make sure that the subfloor material is dry and level. If you find any high spots or low spots, you will need to make them level before installation begins to ensure the long-term performance of the floor. In addition, the use of a moisture barrier underlayment will decrease any hollow sounding areas that could occur with this installation method. Make sure that the underlayment used wraps up the wall to completely encapsulate the flooring. Then, when the last board is put into place, trim off the excess underlayment.
No matter which installation method you choose, the same basic installation principles apply to each method: follow all manufacturer recommendations for installation, rack the wood in advance to avoid “H” joints and stair-stepping, and allow for enough expansion area for the product being installed.
The National Wood Flooring Association provides detailed guidelines for each installation method in its Hardwood Flooring Installation Guidelines, which is provided to all NWFA members at no charge. Nonmembers can receive a copy of these guidelines as well. For more information, contact the NWFA or visit www.nwfa.org.
The National Wood Flooring Association is an international not-for-profit trade organization of more than 4,100 wood flooring professionals working worldwide to educate consumers, architects, designers, and builders in the uses and benefits of wood flooring. The NWFA is located at 111 Chesterfield Industrial Blvd., Chesterfield, MO 63005, and can be contacted at 800-422-4556 (USA), 800-848-8824 (Canada), and 636-519-9663 (international).