Factory Finished Wood Flooring Installation
August 8, 2011
Factory finished wood flooring over the past 10-15 years has become a bigger and bigger portion of the wood flooring market. Back in the ’80s and early ‘90s choices for solid wood factory finished flooring were mostly seal and wax finished flooring. Engineered flooring at that time was offered in conversion varnished finishes which was the forerunner to the UV cured finishes. Since then, most major manufacturers and some smaller manufacturers offer factory finished flooring using an ultra violet cured finish system. Some manufacturers offer finished flooring almost exclusively over unfinished flooring.
Factory finished flooring is almost exclusively packaged in boxes to protect the finish during handling. As such, included in the box is an instruction sheet for installation. This means the flooring contractor has no excuse for not knowing the correct installation procedure for the particular brand of flooring. In addition the overall look of a particular flooring product or skew item is proprietary to that manufacturer. As the flooring contractor we are not privy to the grading guidelines of the manufacturer so we have to rely on their quality control to package the proper product as sold. Mistakes will be made, but in the manufacturer’s defense, they are generally minimal as the flooring is checked at more stations during the inspection process than with unfinished flooring.
First, let’s review the basics of these general instruction sheets. The first instruction item usually mentioned is that of responsibility. If you install it, “you own it.” That is, if the flooring piece is originally defective and installed anyway, it is no longer the manufacturer’s problem. As such we must look over the flooring in a general manner before installation. Pieces that obviously stand out as unusual should not be installed. This includes such items as: unsquare ends; unsound cracked, split, or splintered boards; too dark or too light boards in a similarly light or dark floor; boards that obviously don’t fit the adjacent board; and other similar conditions. Customer expectations also play a part in that even though a board may fall within the variations of the overall product, a consumer may object to items such as discoloration and other natural wood characters.
The overall corollary is to open multiple boxes to mix and rack or lay out in the rooms to be installed. Then, review the rack for obviously “unacceptable” boards. Most of the time cuts can be made of the offending character and a significant portion of the boards can be used. If the number of outs approaches 5% or more of the pieces, you should inform the supplier not only to get replacement boards but to keep from running out of material. The sooner replacement arrives the better you can blend it into the original flooring. I say this since the new flooring may be from another manufacturing run and thus look slightly different, but when randomly mixed with the existing flooring will blend.
The second instruction item is about the condition of the site. The jobsite is usually farther along in the construction process for factory finished flooring installations than are site finished installations. This is one reason particularly in large developments that factory finished flooring will generally have fewer problems. The main reason is that the extra or excessive moisture of construction has more time to dry. However, the rules are still the same; the interior environment should be near occupied conditions for installation to begin. Most instructions require the HVAC to be in place and operating. This requirement can be difficult to meet particularly in the south where permanent electrical service is not passed until just before occupancy. Winter weather in the north dictates the heating must be on to prevent freezing. This can also be a problem with new construction in that too much heat can overly dry a site. The key is to use a reliable moisture meter to check wood members of the installation. Moisture content readings above 12-13% automatically should wave the red flag, except in areas like the gulf states where somewhat higher readings can be expected. Another requirement often stated is that the recommended relative humidity of 35% to 55% (some state 30% to 50%) must be established before installation and continued after installation in order for flooring to perform. In many areas of the country this specification cannot be met in the winter, even with an HVAC attached humidifier. When issues arise with the flooring and the registered humidity is below the 30%-35% the blame is often directed to the home owner for not maintaining the requirement. This is particularly evident with issues reported with engineered flooring. The consumer must therefore be informed that unusual efforts may be necessary to keep the humidity up during winter heating or the flooring will not perform as expected.
The next instruction items are those of actual installation and the requirements for the substrate. As with the requirements for site finished flooring these are similar. A structurally sound, clean, dry, and adequately flat substrate is the requirement. Most instructions for a wood framed structure call for a “code plus” system. That is 23/32” thick subflooring spaced on joists no more that 19.2” O.C. As I have reported before, 24” joist spacing is a minimum code requirement and the ultimate performance of wood flooring will suffer. The minimum system assures that you shouldn’t “fall through the flooring system” but an optimally quiet floor with minimal gaps may not be the normal expectation.
With a concrete slab installation the primary requirement is the vapor retarder that prevents moisture from affecting the flooring. For a direct adhesive flooring application, the troweled-on systems compatible with the adhesives are necessary for moisture protection. For fastened/nailed flooring systems, the plastic film or the adhesive vapor retarders placed on the slab under the subflooring serve the purpose.
These are some of the basic manufacturer’s instructions. So how should the flooring contractor address them? They should be followed as closely as possible. Check the site with a moisture meter. If you don’t test moisture and record readings you set yourself up for at least some responsibility should an issue occur later. If readings are not in the recommended range, a letter to the involved parties as to expected consequences if their decision is to proceed with the installation under the reported adverse conditions can help protect you later. Too high moisture can lead to cupping and later permanent gapping. Too low moisture can lead to permanent cupping in addition to movement and noisy floors.
Most instructions for solid flooring require that you check the flooring itself for proper acclimation. Engineered flooring may or not require acclimation as the milling tolerance is tighter than with solid wood and a significant change in moisture can adversely affect the fit. Finished flooring will be slow to acclimate as it is finished on one side and packed in boxes that inhibit air circulation slowing any acclimation. Determining the moisture condition of the flooring requires that you open several boxes (8 to 10) and randomly check the moisture content of two or three planks in each box and record and average the readings. The closer to the average expected seasonal moisture content of the geographical area, the better. If the average is significantly outside the expected range (more than 1 to 1 ½%) open the boxes and provide air circulation using fans to help accelerate acclimation. After a few days recheck the same planks previously measured. If the average reading is still too low, providing field spacing during installation can accommodate the expected seasonal moisture gain. For too high readings, installing such a product will likely result in permanent gaps and related noises that will result in a call back. So continue to acclimate by drying the flooring with air flow from fans and possibly a dehumidifier.
We have talked about layout before so the general basics are to start near a long straight wall line and/or near the center of the building for a whole house installation. Nail and or glue the starter rows as recommended in the instruction and provide proper expansion space at wall lines. For a later cupped floor issue lack of adequate expansion spacing can allow blame to be directed at inadequate installation. Another issue that arises with nail-down flooring is marring that is associated with the nailing operation itself. The instructions generally warn to check the nailing shoe of the nailer for smoothness and use a wide shoe attachment to better cushion the contact with the flooring. Even with all these precautions, sometimes the finish will fracture showing a dimple on the face near to the fastener. This can be associated with some harder and more brittle finishes. Using cleats instead of staples may help reduce this condition since less wood fiber is displaced during nailing.
Finally, it is important to handle the already finished product carefully. If scratching and marring of flooring is noticed directly after installation they will almost exclusively be connected to installation procedures and require repair. For adhesive applications remove any errant adhesive immediately as it is noticed. Also use a clean rag for wiping each adhesive spill as soiled rags produce smudges that don’t magically disappear. And use the proper filler and/or touchup color to repair and hide the errant blemish or nail hole in the flooring. The job is not completed until all thresholds or transition strips are installed. Extra attention to fitting and finishing these final touches is what will often set the quality installation above the ordinary installation.
Factory finished flooring reacts just like a site finished flooring product only slower initially. Factory finishes require careful handling to maintain the out of box condition. A factory finished floor will not be as flat as the site finished floor for the obvious reason it is not finished all at the same time so some height and plank variation is expected. Factory finished flooring should be maintained similarly to site finished flooring.