What is a soffit?

What does a soffit do?

A soffit closes off the eave so wind, rain and wildfire embers have a harder path into the attic, and FEMA's 2019 Hurricane Michael advisory shows what happens when one fails: “Properly installed and braced soffits resist wind forces and keep water out when the wind drives rain against the outside walls pushing through soffits and into the home's attic.” Source: Federal Alliance for Safe Homes (FLASH), read 2026-10-29. In Santa Barbara County, California, “Home eaves are considered heat traps so closing the space with fascia board and soffit panels helps to prevent a fire from igniting inside a home.” Source: Santa Barbara County Fire Safe Council, read 2026-10-29. In Santa Barbara County, California, “Open eaves are very susceptible to heat from flames, which can become trapped, allowing fire to spread through attic vents and into the attic.” Source: Santa Barbara County Fire Safe Council, read 2026-10-29. “Soffits have historically performed poorly in hurricanes and are commonly damaged in high-wind events.” Source: Federal Emergency Management Agency (FEMA), read 2026-10-29. “When soffits fail, the result is often significant water intrusion.” Source: Federal Emergency Management Agency (FEMA), read 2026-10-29.

How do FLASH and the Department of Energy describe a soffit?

A soffit is the panel or surface that closes in the underside of a roof overhang, the eave, between the roof edge and the outside wall. The Federal Alliance for Safe Homes (FLASH) and the U.S. Department of Energy's Building America guide describe it this way: “A soffit is a horizontal surface outside on the underside of the eaves.” Source: Federal Alliance for Safe Homes (FLASH), read 2026-10-29. “The eave is the area of the roof that overhangs the exterior walls.” Source: Federal Alliance for Safe Homes (FLASH), read 2026-10-29. In Santa Barbara County, California, the Fire Safe Council puts it: “A soffit encloses the underside of sloped or flat-roof overhangs.” Source: Santa Barbara County Fire Safe Council, read 2026-10-29. “Do you see vents in the soffits (the wood panel covering the underside of the eaves) as shown in Figure 2?” Source: U.S. Department of Energy Building America Solution Center (Pacific Northwest National Laboratory), read 2026-10-29.

What is soffit made of?

FEMA lists four typical soffit materials (vinyl, wood structural panels, fiber-cement and aluminum), and a California fire-safety guide adds stucco and notes how each behaves in a fire: “Typical soffit materials used include vinyl, wood structural panels, fiber-cement, and aluminum.” Source: Federal Emergency Management Agency (FEMA), read 2026-10-29. In Santa Barbara County, California, “Soffits are commonly constructed from fiber-cement panels, metal panels, stucco, vinyl panels, or wood sheathing.” Source: Santa Barbara County Fire Safe Council, read 2026-10-29. In Santa Barbara County, California, “Metal panels conduct heat and can distort and allow passage of embers and hot gasses, untreated wood panels can ignite, and vinyl panels can melt and fall away.” Source: Santa Barbara County Fire Safe Council, read 2026-10-29. In Santa Barbara County, California, “Soffits should be constructed with noncombustible materials with a minimum 1-hour fire-resistance rating and contain vents.” Source: Santa Barbara County Fire Safe Council, read 2026-10-29.

Where is the soffit on a house?

Look up at the underside of the roof overhang along the long sides of the house, where the roof edge sticks out past the outside wall; the DOE Building America guide says: “Look under the roof eaves, on the long sides of your roof, not the pointed gable ends.” Source: U.S. Department of Energy Building America Solution Center (Pacific Northwest National Laboratory), read 2026-10-29. In Santa Barbara County, California, “Eaves are located at the down-slope edge of a sloped roof and serve as the transition between the roof and fascia/wall.” Source: Santa Barbara County Fire Safe Council, read 2026-10-29. See the Federal Alliance for Safe Homes (FLASH) passage quoted above.

What are soffit vents?

Soffit vents are openings in the soffit that let outside air into the attic; FLASH lists them as one of five kinds of attic ventilation opening, and they can run continuously or sit every couple of feet: “Attic ventilation openings include soffit vents, ridge vents, off-ridge vents, gable rake vents, and turbines.” Source: Federal Alliance for Safe Homes (FLASH), read 2026-10-29. “They may be nearly continuous or spaced every couple of feet.” Source: U.S. Department of Energy Building America Solution Center (Pacific Northwest National Laboratory), read 2026-10-29. “Effective attic ventilation is important to prevent ice dams from forming on the roof in the winter and to keep the attic cool during the summer.” Source: U.S. Department of Energy Building America Solution Center (Pacific Northwest National Laboratory), read 2026-10-29.

Do soffits need to be vented?

Where the attic above is vented, the code sections printed by the City of Blaine, Minnesota (R806, 2015 Minnesota State Building Code) call for 1 square foot of vent per 150 square feet of attic, or 1 per 300 with the vents split high and low; the DOE guide notes a home without soffit vents likely has an unvented attic: In Blaine, Minnesota, the city's roof-ventilation handout prints code section R806.1: “Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters shall have cross ventilation for each separate space by ventilating openings protected against the entrance of rain or snow.” Source: City of Blaine, Minnesota, Building Inspection, read 2026-10-29. Section R806.2, as printed there, reads: “The total net free ventilating area shall not be less than 1 sq. ft.to 150 sq. ft. of the area of the space ventilated except that the total area is permitted to be reduced to 1 sq. ft. to 300 sq. ft., provided at least 50 percent and not more than 80 percent of the required ventilating area is provided by ventilators located in the upper portion of the space to be ventilated at least 3 feet (914 mm) above eave or cornice vents with the balance of the required ventilation provided by eave or cornice vents.” Source: City of Blaine, Minnesota, Building Inspection, read 2026-10-29. In Santa Barbara County, California, “Note that with enclosed soffits, some vents need to be added.” Source: Santa Barbara County Fire Safe Council, read 2026-10-29. “If your home does not have soffit vents, it likely has an unvented attic and does not need baffles.” Source: U.S. Department of Energy Building America Solution Center (Pacific Northwest National Laboratory), read 2026-10-29. “Roofs with these vents do not need soffits because the vent is installed above the insulation.” Source: U.S. Department of Energy Building America Solution Center (Pacific Northwest National Laboratory), read 2026-10-29.

Do soffits connect to the attic?

Yes. In a vented attic the soffit vents are the low intake, and air moves from them up under the roof deck, which is also why wind-driven rain and embers can reach the attic through the soffit: “Attic baffles are foam or cardboard channels that extend from the floor of the attic along the eaves up along the underside of the roof deck to provide a path for ventilation air coming in the soffit vents to flow up the underside of the roof past the insulation.” Source: U.S. Department of Energy Building America Solution Center (Pacific Northwest National Laboratory), read 2026-10-29. See the Federal Alliance for Safe Homes (FLASH) passage quoted above. See the Santa Barbara County Fire Safe Council passage quoted above.

Can soffit vents get clogged?

Yes, attic insulation is the common culprit, which is why code section R806.3 asks for at least a 1-inch air space at each vent and why foam or cardboard baffles are fitted in each rafter bay: In Blaine, Minnesota, the city's handout prints code section R806.3: “Where eave or cornice vents are installed, insulation shall not block the free flow of air.” Source: City of Blaine, Minnesota, Building Inspection, read 2026-10-29. “A minimum of a 1-inch (25.4 mm) space shall be provided between the insulation and the roof sheathing at the location of the vent.” Source: City of Blaine, Minnesota, Building Inspection, read 2026-10-29. “Baffles keep insulation from blocking the soffit vents and keep air from blowing through the attic insulation (Figure 1).” Source: U.S. Department of Energy Building America Solution Center (Pacific Northwest National Laboratory), read 2026-10-29. “If your home has continuous soffit vents, there should be a baffle in every rafter bay.” Source: U.S. Department of Energy Building America Solution Center (Pacific Northwest National Laboratory), read 2026-10-29. In Santa Barbara County, California, “Make sure to maintain existing vents and upgrade for ember resistance with metal mesh with ⅛ -inch or smaller opening to allow for circulation while preventing ember entry.” Source: Santa Barbara County Fire Safe Council, read 2026-10-29.

Are soffits required by code?

The sources read for this page do not say every house must have a soffit; they set rules for soffits that are built, starting with wind loads under the 2015 International Residential Code (IRC): “Until recently, building codes provided little guidance on designing soffits for wind loads.” Source: Federal Emergency Management Agency (FEMA), read 2026-10-29. “Both the 2015 IRC and ASCE 7-10 were also revised to require that soffits be capable of resisting the wind loads specified for walls.” Source: Federal Emergency Management Agency (FEMA), read 2026-10-29. In Florida, “The 2007 FBC was revised to require that soffits be capable of resisting the same wind loads required for walls.” Source: Federal Emergency Management Agency (FEMA), read 2026-10-29. See the Santa Barbara County Fire Safe Council passage quoted above.

Sources

• Roof Ventilation (prints code sections R806.1-R806.3, 2015 Minnesota State Building Code) — City of Blaine, Minnesota, Building Inspection; read 2026-10-29.
• Hurricane Michael in Florida Recovery Advisory 2: Best Practices for Minimizing Wind and Water Infiltration Damage (June 2019) — Federal Emergency Management Agency (FEMA); published 2019-06; read 2026-10-29.
• Brace Soffits for Storm Safety — Federal Alliance for Safe Homes (FLASH); read 2026-10-29.
• Look for and Install Attic Vent Baffles — U.S. Department of Energy Building America Solution Center (Pacific Northwest National Laboratory); read 2026-10-29.
• Wildfire Home Hardening Guide: Eaves — Santa Barbara County Fire Safe Council; read 2026-10-29.