Wood floors go hand-in-hand with old houses. They’re traditional and functional—as well as having finishes highly valued for their rich historic character and warm beauty. Little wonder then why the phrase "hardwood floors" is such a magnet in the real estate market, especially given that the generation of wall-to-wall carpet houses from the 1960s and '70s were built without any finished flooring at all. Enduring as they are, wood floors bear tremendous amounts of use, abuse, and changes and, after many decades of service, they often need repairs or replacements. Since most folks don't wonder about the specifics of wood-floor construction and care until it's time to act, here’s a rundown of the common issues that surface in the quest to keep up old floors or blend in new flooring seamlessly.
Q: What’s the history of wood flooring?
A: The most common kinds of wood flooring in old houses can be divided into two general categories: wide-plank floors (boards typically 8" and wider) often seen in early buildings, rural areas, or secondary spaces like bedrooms and kitchens; and strip floors (narrow boards typically 2" to 4" wide), at first reserved for better rooms but nearly ubiquitous in most houses by the 20th century. Wide-board floors are the oldest and simplest type. In most areas they were originally constructed of softwoods like pine that were durable but easy to hand-saw, then face-nailed to supporting beams or joists.
True strip floors are a product of the Industrial Revolution, and started to become widely affordable and reliable in quality in the 1880s. Steam-powered machinery, which made the milling of dense hardwoods like oak and maple practical, also enabled edge-matching the sides of each board into a sophisticated system of tongue-and-groove joints. This system not only integrates hundreds of small boards into a wood "skin" that shares loads among many boards, but it also makes possible blind-nailing where nail heads are recessed below the surface for better appearance and durability.
The woods used for flooring have always depended upon what species were available and affordable locally, as well as what was attractive or fashionable. Though softwoods like pine (of which there are many kinds) have always been popular for wide-board floors, hard pine and fir are regularly used as strip flooring, and hardwoods like ash, elm, and chestnut have also been employed for wide-board floors.
Q: What is quarter-sawn flooring?
A: When it comes to spec’ing new flooring for repairs or replacements, the cut of the wood is as important as the species. Like many other wood building materials, flooring is commonly either flat-sawn or quarter-sawn. In flat sawing, the simplest method, all boards are sawn from the log in the same manner, like slicing bacon strips. The more sophisticated cut particularly coveted for flooring is quarter-sawing. Though sawmills can choose among several methods of quarter-sawing depending upon their needs, the basic practice is to first saw the log into equal quarters, then to reposition each quarter and flat-saw across the quarter. This method produces boards that are more dimensionally stable with a more uniform appearance.
Q: What are the cuts on the bottoms?
A: Called undercutting or relieving, grooves have been milled into the undersides of some flooring since at least 1900 to both allow the flooring to rest more solidly on a subfloor and/or to minimize the potential for warping. Other nuances of construction that are important to look for when buying replacement flooring are end-matching (tongues and grooves on board ends, particularly on random-length flooring), and the matching dimensions (better quality flooring of the past had more wood above the tongue than below it to allow for finish scraping). Note that modern prefinished flooring is often made with a "micro-bevel" along each side of the top surface that eliminates the need for finish sanding, but may not be compatible with traditional strip flooring.
Q: Can I install flooring the day it arrives?
A: Whether you are repairing an existing floor or laying a new one, it is critical to have the flooring materials at the same moisture level as the room before they are installed. This means leaving the materials stacked with spacers in the room they will occupy for as long as possible—two weeks at a minimum. Without this time, there is a real chance the flooring will dry out and shrink after it is installed, resulting in unsightly gaps between boards, or pick up moisture and expand, creating the potential for buckling. Though manufactured flooring is shipped kiln-dried to an industry standard, this does not mean it cannot pick up additional moisture later. Storage in an unheated garage or installation in the same building with fresh plasterwork or poured concrete that is still drying can have a drastic effect.
Q: How do you patch strip flooring?
A:While old-house strip floors occasionally suffer isolated damage from deep burns to animal gouges that require a small, surgical repair, the more common scenario is an in-fill patch—that is, adding new flooring to cover the space of a removed wall, say, or a large duct hole cut in the floor. Here the most unobtrusive repair involves not only matching the wood and cut of the old flooring as closely as possible, but also blending the repair into the existing installation by "fingering in" new boards so they match the spacing of the rest of the floor as closely as possible. To do this, you must cut back selected boards at varying positions, then splice in new boards—all without disturbing the flooring you want to keep.
Start by thoughtfully planning your repair. Measure the offset of the joints in your existing floor, then plot out a similar pattern in the area you need to patch. Do your best to take advantage of the joints already in your favor so that you minimize the work and loss of good materials, while making most effective use of your repair stock (which may be limited if you are recycling flooring). Typically, you want to have boards no shorter than about 24" and a minimum cutback of 9" to 12" to maintain the structural integrity of the tongue-and-groove system.
Next, mark the boards you plan to remove and scribe cut lines at right angles across the boards where you will make a joint. Bore a 3/4" hole in each board on the waste side of the line, positioning it in the center of the board to avoid any flooring nails. Then, starting from the hole, cross-cut the board with a saber saw, working tangent to the circle circumference. To avoid cutting the subfloor underneath, shorten the saber-saw blade by snapping it with pliers so that its maximum travel just reaches the bottom of the finished flooring.
Afterwards, working from the hole, saw two kerfs down the center of the board to cut out a relief strip—wood that once removed allows you to pry out the groove and tongue sides of the board without damaging the adjacent flooring. Make these blind cuts with a circular saw, setting the blade depth to just about the thickness of the flooring.
Q: How do you get new boards into the tongues and grooves?
A: With an in-fill repair, you can often slide some of the new flooring into place between the existing tongues and grooves. Where this is not possible, though, you have to "cheat in" the new board around the system. One method is to cut off the bottom groove shoulder of your patch board so you can nose the tongue into place (usually with a little planing of the bottom corner of the board), then pop the groove over the existing tongue. To secure the board, you either face-nail the board with finishing nails (which are set and filled) or you can glue the board to the cut-off portion of the shoulder that you have put in place beforehand.
Q: What about strip floors that are basically sound but squeaky?
A: Squeaks and springy spots in old floors are, strictly speaking, not normal. Solutions vary with the construction of the floor and the cause—generally, insufficient contact with the subfloor. If you can get below the floor, first have someone walk around on top so you can identify the location and source of problems—often shrunken or poorly supported subfloor boards. Try adding support by nailing a cleat (a 1" or 2" stick) alongside a joist, or driving a wood screw up through the subfloor to secure a loose floorboard. Where you have no access from below, or the problem stems from a loose-fitting tongue and groove, try driving two ribbed finish nails at opposing angles—preferably into a joist—to secure the floorboards.
Q: After taking the finish off an old floor, can you stain the wood?
A: Yes, but you should know what you’re getting into first. Many an old-house owner has stained a freshly sanded floor and returned to find that, contrary to their expectations of a mellow grain pattern, the floor has become a mess of blotchy patches. This is the result of uneven stain absorption. What’s the reason? Though most bare wood takes stain in varying degrees depending upon what part of the grain structure is exposed—the very effect desired with stain—a newly sanded old floor presents a different scenario. Here, some areas of wood are exposed much as they would be newly milled wood, while others still retain old finish that has deeply penetrated the surface, effectively sealing the wood pores from stain penetration. Extreme conditions like sunk-and-filled nails or spot repairs exacerbate the difference. What’s the solution? Test the effects of the stain first in a limited, out-of-the-way area, and if you anticipate any problems, prepare the surface first with a stain controller—a finishing product that evens the absorption of the wood.