Wood flooring
Wood flooring is any product manufactured from timber that is designed for use as flooring, either structural or aesthetic. Wood is a common choice as a flooring material and can come in various styles, colors, cuts, and species. Bamboo flooring is often considered a form of wood flooring, although it is made from a grass (bamboo) rather than a timber. Types. Solid. Hardwood flooring. Solid hardwood floors are made of planks milled from a single piece of timber. Solid hardwood floors were originally used for structural purposes, being installed perpendicular to the wooden support beams of a building  known as joists or bearers. With the increased use of concrete as a subfloor in some parts of the world, engineered wood flooring has gained some popularity. However, solid wood floors are still common and popular, but are commonly more expensive in the United States and considered higher end. Solid wood floors have a thicker wear surface and can be sanded and finished more times than an engineered wood floor. It is not uncommon for homes in New England, Eastern Canada, USA, and Europe to have the original solid wood floor still in use today. Solid wood manufacturing. Solid wood  flooring is milled from a single piece of timber that is kiln or air dried before sawing. Depending on the desired look of the floor, the timber can be cut in three ways: flat-sawn, quarter-sawn, and rift-sawn. The timber is cut to the desired dimensions and either packed unfinished for a site-finished installation or finished at the factory. The moisture content at time of manufacturing is carefully controlled to ensure the product does not warp during transport and storage. A number of proprietary features for solid wood floors are available. Many solid woods come with grooves  cut into the back of the wood that run the length of each plank, often called 'absorption strips,' that are intended to reduce cupping. Solid wood floors are mostly manufactured thick with a tongue-and-groove for installation. Other wood manufacturing styles. Rotary-peel. This process involves treating the wood by boiling the log in water. After preparation, the wood is peeled by a blade starting from the outside of the log and working toward the center, thus creating a wood veneer. The veneer is then pressed flat with high pressure. This style of manufacturing tends to have problems with  the wood cupping or curling back to its original shape. Rotary-peeled engineered hardwoods tend to have a plywood appearance in the grain. Sliced-peel. This process begins with the same treatment process that the rotary peel method uses. However, instead of being sliced in a rotary fashion, with this technique the wood is sliced from the log in much the same manner that lumber is sawn from a log – straight through. The veneers do not go through the same manufacturing process as rotary peeled veneers. Engineered hardwood produced this way tends to have fewer problems with "face checking", and  also does not have the same plywood appearance in the grain. Dry solid-sawn. Instead of boiling the hardwood logs, in this methods they are kept at a low humidity level and dried slowly to draw moisture from the inside of the wood cells. The logs are then sawn in the same manner as for solid hardwood planks. This style of engineered hardwood has the same look as solid hardwood, and does not have any of the potential problems of "face checking" that rotary-peel and slice-peel products have, because the product is not exposed to added moisture Engineered . Engineered wood flooring consists of two or more layers of wood adhered together to form a plank. Typically, engineered wood flooring uses a thin layer (lamella) of a more expensive wood bonded to a core constructed from cheaper wood. The increased stability of engineered wood is achieved by running each layer at a 90° angle to the layer above. This stability makes it a universal product that can be installed over all types of subfloors above, below or on grade. Engineered wood is the most common type of wood flooring in Europe and has been growing in popularity in  North America. Laminate and vinyl floors are often confused with engineered wood floors, but are not. Laminate flooring uses an image of wood on its surface, while vinyl flooring is plastic formed to look like wood. The several different categories of engineered wood flooring include: Comparison of solid wood with engineered wood. It is difficult to compare solid wood flooring to engineered wood flooring due to the wide range of quality in both product categories and each type has its limitations. Solid hardwood is more prone than engineered timber to "gapping" (excessive space between planks), "crowning" (convex curving upwards when  humidity increases) and "cupping" (a concave or "dished" appearance of the plank, with the height of the plank along its longer edges being higher than the centre) with increased plank size. Patented installation systems for engineered wood may allow for faster installation and easy replacement of boards. Engineered wood also allows for a floating installation where the planks are not fastened to the subfloor, but to each other. Engineered flooring is suitable for underfloor and radiant heating systems, while solid wood cannot be used with underfloor heating. Some characteristics are common to each category: solid wood is more frequently  site-finished, is always in a plank format, is generally thicker than engineered wood, and is installed by nailing. Engineered wood is more frequently pre-finished, is very rarely site-finished and is installed by staple down or floating installation. Installation systems. Wood can be manufactured with a variety of different installation systems: Finishing, buffing, sanding and drying. Buffing. Generally, older solid hardwood floors need to be buffed every 3–5 years. The process usually takes about one day. Buffing refers to the process of using a stand up floor buffer. The floor is abraded with 180 grit screen on the  buffer. This allows for the new coat of finish to mechanically adhere to the floor. This process works with great results as long as the floor hasn't had any waxes or synthetic cleaners. Factory finished floors do not require buffing. Refinishing. Sanding the finish off old wood floors and smoothing them out. Floor sanding. Sanding provides a method for smoothing an installed floor, compensating for unevenness of the subfloor. Additionally, sanding is used to renew the appearance of older floors. Sanding using successively finer grades of sandpaper is required to ensure even stain penetration when stains are used, as  well as to eliminate visible scratches from coarser sandpaper grades used initially. Prior to modern polyurethanes, oils and waxes were used in addition to stains to provide finishes. Beeswax and linseed oil, for example, are both natural crosslinking polymers and harden over time. Floor scraping. Prior to the 20th century, hardwood floors were refinished by scraping. This process revealed undamaged wood but left many shallow gouges in the floor. Scraping may be performed using such tools as chisels, planes, and cabinet scrapers. Modern methods duplicate this using proprietary machinery.