What Is the Spacing of Furring Strips for Metal Roofs?

Every type of roof has unique features that help it stay put and protect your home. If you’re installing a metal roof, one of the most common features is known as furring strips. These carefully-placed pieces of wood stripping, which rest underneath your roofing, have a big impact—but only if you install them correctly. This guide will show you the perfect spacing of furring strips for metal roofs.

What are Furring Strips?

Typically, homeowners use furring strips for metal roofs if they’re installing roofing over existing shingles—but that’s not the only use case. They’re also beneficial for homes with unfinished attics, poor attic insulation, and limited ventilation. This type of wood stripping comes with a number of benefits, which include:

• Increased insulation

• Improved ventilation

• Improved drainage 

• Minimized condensation

• Reduced noise

• Leveling a damaged or uneven roof deck

Remember: metal roofs can get hot in the sun, particularly if they’re installed over asphalt. Furring strips help minimize heat transfer between your metal roof and roof deck, which can increase your home’s energy efficiency. Since they also help secure your roof, they’re typically recommended or even required by local building codes.

Factors for Determining the Spacing of Furring Strips on a Metal Roof

As a general rule, furring strips are usually spaced somewhere between 12 inches to 24 inches apart. Building codes vary and certain manufacturers may have slightly different instructions. Regardless, the type of roof and the slope will impact spacing. The closer together you place your strips, the more support they’ll give your roof.

Type of Roof

Certain types of metal roofing need more furring strips than others. Here are some spacing guidelines based on type:

• Corrugated metal roofing: space your strips up to 24 inches apart

• Standing seam metal roofing: space your strips up to 18 inches apart

Some homeowners try to cut down on roof replacement costs by using as few furring strips as possible—or skipping out altogether despite contractor recommendations. This typically isn’t advisable. It’s especially important to use furring strips if you’ve already installed shingles. Otherwise, your roof could have moisture issues and look uneven (metal panels tend to conform to the shape of the shingles over time).

Slope of Roof

The steeper the slope on your roof, the further apart you can space your furring strips. You’ll need to know your roof pitch before you begin installation. Here are some guidelines:

• Low slope (a pitch of 2/12 or less): space your strips up to 16 inches apart

• Steep slope (a pitch greater than 2/12): space your strips up to 24 inches apart.

Should I Repair Existing Furring Strips?

Furring strips are made from wood, so if they start to rot, you will need to replace them. This type of installation is best done by a metal roof repair service near you. A poor installation can lead to numerous issues. 

If your furring strips are too far apart, they won’t adequately support your roof. If they’re too close together, you’ll have to poke too many holes in your roofing material, which could compromise the structural integrity. You need the perfect balance, and a contractor has the experience to do it right.

When you make your budget, keep in mind that furring strips add to the cost of a metal roof. It’s typically a worth-it expense because it will help prevent issues that prematurely age your roof.