Furring strips are thin, long pieces of metal or wood attached to an unfinished wall in order to support various finishing surfaces or to fill out uneven sections of a wall being resurfaced. A furring strip is commonly 1 inch (2.5 cm) by 2 inches (5 cm) or 1 inch (2.5 cm) by 3 inches (7.5 cm) in size, and is fastened horizontally or vertically to the existing wall. In home renovations, they are often used when remodeling a basement where the existing walls are made of exposed concrete, blocks or bricks. Furring strips provide non-structural support and a solid surface to which to attach finishing materials like paneling or backing boards. How the strips should be attached and spaced is determined by the material of the existing wall and the finishing material that will be attached to the strips.
Furring strips are usually made of solid wood, but can also be made of metal if building codes require supporting elements to be fireproof. In some cases, furring strip construction is used in roofing, most commonly for buildings like barns and sheds, though plywood is often used instead. Not all types of wall-coverings require the use of these strips. For example, drywall can be installed without them, and when installing a plaster wall, other construction methods are used.
Furring strip installation varies depending on what kind of finishing materials one is using. When installing the heavy boards used as backing material for ceramic tiles, the furring strips have to be spaced widely apart. When the finishing material is thin paneling, the strips can be spaced closer together. Furring strips can be used during a remodel both to add new wall-finishing materials and to add wall insulation. It is often recommended to use 2 inch (5 cm) by 4 inch (10 cm) sized wood for the furring strips when adding insulation, instead of the narrower wood used otherwise.
It is usually easiest to fasten the furring strips vertically, and they should be attached the entire height of the wall. The strips should be fastened using screws, nails, or appropriate glue, for example Liquid Nails or a similar product. Appropriate fasteners, like concrete screws or concrete anchors, should be used if the existing wall is made of concrete, brick, or blocks. When using strips made of metal, refer to the manufacturer's installation instructions. Always make sure your project follows the building codes in the area where you live.
