Furring strips are an important construction element. They are long, narrow beams of wood that separate two construction surfaces. Furring strips allow you to install a flat surface over a textured one. By providing an even structure on which to lay flat materials, like metal roofing or drywall, furring strips provide for secure installation.
Benefits of Furring Strips
There are two main benefits of furring strips. They create a frame on which to secure flat materials when the underlying structure isn’t completely even. These strips also provide an air pocket between the two surfaces. Although furring strips are often made of wood, they can be composed of metal.
Creating a frame provides support for the outer layer of material. You can’t always attach certain materials to others. For example, drywall shouldn’t be installed directly over concrete without a buffer. The furring strips are connected to the support material using the appropriate fasteners. The outer material, such as drywall, is attached to the wooden furring strips.
Furring strips aren’t the same as studs. They fill in the spaces between the studs to add extra support to the final layer of material. Furring strips can be installed parallel or perpendicular to the studs at various intervals, depending on the type of material that will be applied to them.
Heavier outer materials require more furring strips. Otherwise, the outer material can sag and end up resting on the inner layer.
You should aim to keep an air space between these two layers, though. The air pocket improves insulation. It also improves airflow, preventing condensation from building up on the surfaces and creating moisture damage.
Furring Strips for Walls and Ceilings
Imagine the concrete walls of a basement. There are seams between the blocks, and the surface of the concrete may be pitted. Concrete can feel cold to the touch, and you may want to enclose the material with drywall for a warmer feel and better insulation. But you can’t adhere the drywall directly to the uneven surface of the concrete.
You would need to “furr the wall.” In other words, attach a grid of furring strips to the concrete. They serve as a surface to which you can fasten the drywall.
In this case, you don’t need the structural support of wall studs. Therefore, furring strips can be installed in place of the studs. They’re typically attached every 16 inches. Drywall or plaster is easily installed over the strips.
You can use a similar technique for the ceiling. Furring strips can be added so that you have a secure structure for clipping on ceiling tiles.
Furring Strips for Siding
As long as they’re made from a moisture and weather-resistant material, furring strips can be used outside of the home. They are often used for siding installations.
Homes are usually wrapped with a weather-resistant barrier. The furring strips create space between this barrier and the siding, allowing moisture to drain without getting trapped. If stagnant water lingers against the siding, it can create rot and water damage. Furring strips provide ventilation and water management to prevent this from happening.
When they’re used outdoors, furring strips should be installed vertically. Horizontal beams can trap moisture. When they’re installed at proper intervals, furring strips for siding allow for adequate airflow.
Furring Strips for Roofs
Roofing panels often require additional support. Furring strips can be placed over the decking to create a space between the top layer of roofing and the sheathing.
But most commonly, furring strips are used when installing a metal roof over asphalt shingles. This is a popular way to add a metal roof without the time, effort and expense of removing the existing roof.
However, you will run into problems if you try to lay the metal directly over the asphalt shingles. For one, a shingled roof is textured. The metal panels won’t lay flush with the asphalt. If you don’t use furring strips, the metal roof can develop a wavy appearance. The abrasive shingles can also damage the underside of the metal if they’re in direct contact with each other.
Perhaps more significantly, installing a metal roof directly against a shingled one creates an issue with trapped water vapor. The moisture buildup can create problems with mold, rot and deterioration. Creating an air pocket with furring strips and keeping the two layers of roofing separated reduces the chances of developing water damage in the roof.
You can use furring strips even if you’re installing a metal roof over a traditional roof deck. Adding space using the strips will prevent heat transfer from the outer panels to the sheathing. This can improve the energy efficiency of your home, especially when the insulation or venting in the attic isn’t optimal.
Furring Strips for Tub Surrounds
The area where the wall meets the tub can flare out if it’s not installed properly. Using furring strips behind bathroom wall materials, especially tile, prevents this issue. It helps your tub fit square in the bathroom when the backer board isn’t lining up correctly.
Furring Strips Create Space for Installation
The space that furring strips create between two layers of material isn’t just important for airflow. It can be ample enough to make room for adding insulation. You can use several types of insulation with furring strips, but rigid foam insulation is often the best choice. It’s slim enough to fit between the layers of material and does an excellent job of maintaining the indoor air temperature. Rigid foam insulation is especially useful for installing between a roof deck and the top layer of roofing. It can also be used in walls.
Some people add traditional batt insulation beneath the furring strips, keeping it in place with the strips before adding the final layer of material. This is a simple way to install the insulation. However, it could create moisture problems if you don’t install drainage channels or use an adequate vapor barrier behind the insulation.
When Can’t You Use Furring Strips?
Furring strips are cheaper and easier to install than studs. They can be used in many applications. However, they’re not ideal in the following scenarios:
- Large pipes – Furring strips are smaller than studs and might not provide enough space for large pipes within the walls. In this case, you will be better off using 2 by 4s.
- Extensive wiring – Furring strips can make it difficult to run electrical wire through the space behind the drywall. However, if there’s enough room, furring strips can make it easier to run wire without having to bore holes through studs.
- Thick insulation – Because they don’t create as much space as studs do, furring strips aren’t optimal for using with traditional blanket installation.
If you’re using furring strips in an indoor wall or area that’s protected from water, wood should be fine. However, soft wood shouldn’t be used outdoors, such as for rain screens within siding. Instead, opt for redwood, which is less sensitive to moisture. Pressure-treated wood and other, less permeable materials, are the best bet.
Are you wondering whether you’ll need furring strips for your new roof? Contact a professional roofer to go over your options. Making the right choice now can save you time, money and headaches over the years. It will also keep your home protected from moisture damage and better insulated.