fire setbacks

SIZE OF SOLAR PHOTOVOLTAIC ARRAY

605.11.1.2.1 Size of Solar Photovoltaic Array: Each photovoltaic array shall be limited to 150 feet by 150 feet. Multiple arrays shall be separated by a 3-foot-wide clear access pathway.

For this requirement:

1. On residential systems, you are very unlikely to ever have an array that is 150' by 150' (or 22,500 sq. ft.). This part of the code will not be considered applicable, however, part 2 is.

2. When we have multiple arrays on a single roof plane, we always need to provide a 3' pathway in between these arrays.

   1. The example to the right demonstrates a layout that has two arrays on a single roof plane.

   2. The designer designated and dimensioned this needed pathway on the plans.

SETBACKS AT THE RIDGE

605.11. 1.2. 5 Allowance for Smoke Ventilation Operations: Panels and modules installed on Group R-3 buildings shall be located not less than 3 feet (914 mm) from the ridge in order to allow for fire department smoke ventilation operations.

HIP ROOFS

605.11.1.2.2 Hip Roofs: Panels and modules installed on buildings with hip roof layouts shall be located in a manner that provides one 3-foot-wide clear access pathway from the eave to the ridge on each roof slope where panels and modules are located. The access pathway shall be at a location on the building capable of supporting the fire fighters accessing the roof.

SINGLE RIDGE ROOFS

605.11.1.2.3 Single-Ridge Roofs: Panels and modules installed on buildings with a single ridge shall be located in a manner that provides two, 3-foot-wide access pathways from the eave to the ridge on each roof slope where panels and modules are located. 

ROOFS WITH HIPS AND VALLEYS

605.11.1.2.4 Roofs with Hips and Valleys: Modules installed on buildings with roof hips and valleys shall not be located closer than 18 inches to a hip or a valley where panels/modules are to be placed on both sides of a hip or valley. Where panels are to be located on only one side of a hip or valley that is of equal length, the panels shall be permitted to be placed directly adjacent to the hip or valley.

• When there is an intersecting valley where modules will also be on the other side, neither array may come closer than 18" to this valley.

• When there are modules on either side of a roof hip or there is an intersecting valley with modules on the other side, neither array may come closer than 18" to this valley.

This must always be shown on the plans.

OVERVIEW

This is the short version of the code. It gets a little more granular than this, so make sure to review all the following code specifics to ensure that you fully understand the code language.

• 36” setback on both sides of the ridge

• Two 36” paths for each roof plane where PV is mounted on a single ridge roof

• One 36” path required on hip roofs

• Hip and Valley pathways:

  • When modules are to be mounted on both sides of a hip/valley, 3' must be provided in between arrays.

  • No array is permitted to be closer than 18" to the hip/valley when modules are placed on either side.

This example shows several different ways in which you can design your pathways.

1. For the southmost facing roof, the pathway is straddling the roof with PV and the adjacent roof through the valley.

2. For the northwest array, the pathway was placed on the immediate adjacent roof across the valley.

EMERGENCY ESCAPE AND RESCUE OPENINGS

1204.2.2 Emergency escape and rescue openings: Modules shall not be placed on the portion of the roof that is below an emergency escape and rescue opening. A pathway not less than 36” wide shall be provided to the emergency escape and rescue opening. 

The pathway needs to extend all the way down to the lowest eave, however, you can choose to do the following:

1. A direct 3' path from the eave to the point of egress.

2. A 3' path in front of the widow to one of the edges (rakes) 3' continuous down to the lowest eave.

   • The example to the right shows this.

OVERVIEW

• 18” on either side of the ridge

  • Increase to 3’ when more than 33% of the roof area is occupied by solar.

• Two 3’ paths on two different roof planes from ridge to eave

  • One pathway must extend toward the street or driveway.

  • On hips and valleys:

    • Can be 3’ pathway on the roof with PV

    • Can be 3’ pathway on an adjacent roof

    • Can be 18” on either side of the hip/valley on the roof with PV and the adjacent roof.

MECHANICAL EQUIPMENT CLEARANCES

3111.3.4.6 Mechanical Equipment Clearances: PV panel systems shall be installed with a clearance of not less that 30 inches around mechanical equipment requiring service maintenance. The applicable provisions of the Mechanical Code and Electrical Code apply to installations of PV systems.

• It is recommended to default to 3' clearance around such mechanical units such as HVAC systems, chimneys, etc.

CODE SPECIFICS TO BE AWARE OF

Make sure to pay special attention. Oregon Structural Specialty Code Article 3111.3.4.8 gives specific guidelines:

3111.3.4.8.1 Pathway Requirements: All photovoltaic installations shall include a 36-inch wide pathway maintained along three sides of the solar roof. The [eave] of the roof shall not be used as a pathway.

The image to the right demonstrates a layout made using the guidelines stated above. Note that, this was required due to the PV arrays being placed on both sides of the horizontal ridge:

This will be the case when modules are placed on either side of a horizontal ridge. Note that the code language here is slightly different than the unadulterated 2015 IFC which does not specify that pathways would always be needed on three sides of the array. Additionally, 2015 IFC would state that only one 36-inch path would be needed on a hip roof. The Oregon Structural Specialty Code makes no such allowances for hip roofs when modules are placed on both sides of the horizontal ridge.

Again, note the exceptions in 3111.3.4.8.1:

1. Structures with a photovoltaic array area of 1000 square feed or less installed on a roof with a slope exceeding [2:12 or 9.5 degrees] with an intersecting adjacent roof [A roof section adjacent across the ridge with no PV on it] and where no section is larger than 150 feet measured in length or width.

1.1 & 1.2 would be the contingent area requirement when exception 1 is met. If the total roof area measured in plan view is less than 25% then only a 12-inch offset at the ridge is needed. If greater than 25%, then we will need a single 36-inch pathway from the highest ridge to the lowest eave of the roof section supporting PV.

FIRE FIGHTER ACCESS AND ESCAPE

3111.3.4.8.1 Pathway Requirements: All PV installations shall be provided with pathways not less than 36" in width along not less than three sides of the solar roof plane. The bottom edge of a roof plane with a slope greater than 2:12 shall not be used as a pathway. All  pathways shall be located over a structurally supported area and measured from the edge of the roof and horizontal ridge to the PV array or any portion thereof.

This is very similar to 2015 IFC setbacks and it is recommended that you use 2015 as your template. There are a few key differences:

1. The stipulations stated above regarding roof drainage and clearance from smoke vents and mechanical units.

2. There are conditions that will decrease these setback requirements. Continue to Exceptions

EXCEPTIONS

3111.3.4.8.1. Exception 1: Structures with a PV array area of 1000 sq ft. or less installed on a roof with a slope greater than 2:12 with an intersecting adjacent roof plan and where no dimension of the array is greater than 150' in length:

First, lets look at the code definition of "intersecting adjacent roof. This definition is found under "Solar Roof Plane" in chapter 2 of the 2022 OSSC:

For the purposes of firefighter access and escape pathway provisions, the solar roof plan is contrasted with the adjacent roof plane. To be considered an adjacent roof plane, the roof plane adjacent to the PV array installation must be free of photovoltaic panels.

The highlight and takeaway of this is that:

1. And intersecting adjacent roof plane is a roof clear of PV that is directly adjacent to the roof with PV and can be considered such when it is:

   1. an adjacent hip

   2. a roof plan across the ridge

   3. a roof plane with an adjacent valley.

Here at Ion, it is our policy to only consider it an intersecting adjacent roof plane if this adjacent roof can itself sustain a 3' pathway to the ridge. For instance, a short dormer incapable of sustaining a sufficient fire pathway would not be considered an adjacent roof here at Ion.

The roof sections highlighted green could be considered as intersecting adjacent roof sections according to the code language and Ion policy:

• Each of these roofs are directly adjacent to a roof section with PV

• Each of these roofs are wide enough to accommodate a 36" pathway on their own (though no setbacks need to be drawn on them)

The roof highlighted red would not be considered an intersecting adjacent roof according to Ion policy:

• It is not wide enough to support its own fire pathway

The roof highlighted red would not be considered an intersecting adjacent roof according to code language and Ion policy

• It is not directly adjacent to a roof with PV.

1.1 Where the PV array does not exceed 25%, measured in plan view, of the total roof area of the structure, an unobstructed pathway not less than 12 inches will be provided along each side of any horizontal ridge.

The example to the right shows what a roof meeting these exceptions would look like on the final plan set drawing. Note that because the roof area occupied by solar is less than 25%, the needed pathways were reduced to only  include 1' offset on each side of the ridge.

1.2 Where the PV array exceeds 25%, measured in plan view, of the total roof area of the structure, an unobstructed pathway not less than 36" from ridge to eave over a structurally supported area shall be provided in addition to an unobstructed pathway not less than 12"  along each side of any horizontal ridge.

The diagram on the right demonstrates a roof area with over 25% occupied by PV. The designer took care to draw 36" pathways up to the ridge for each roof housing PV but only a 12" offset was required on either side of the ridge per the exceptions.

3111.3.4.8.1 Exception 2: Pathways are not required on non-occupied accessory structures, provided that they are separated from occupied structures by not less that 60 inches.

This is similar to the standard 2015 and 2018 IFC, however, if the detached and unoccupied structure is within 5 feet of the main home, then the fire pathway requirements will also apply to this structure.

The example to the right shows a non-habitable structure that is over 5 ft. away from the main home. This will not need fire setbacks.

If this same structure was within 5' of the home, then we would need to follow the same fire setback rules as stated above.

On this one, we would need to provide 12" on either side of the ridge and a 3' pathway on one side of the array due to PV occupying over 25% of the structure's roof.

3111.3.4.8.1 Exception 3: Townhouses providing fire separation as required by the applicable code at the time of construction may be considered one structure and are permitted to comply with the provisions of section 3111.4.8.1 Exception 1.1.

Here at Ion, we will consider a townhome as meeting these requirements if you can see a clear partition between units in the attic space:

• Typically newer town home constructions will have units separated by sheet rock with insulation and fire blocking sandwiched in-between.

  • You may also see cinder block "party walls" used in a similar way in multifamily homes.

• If you see proper sheetrock or cinder block walls separating the attic space between units, we can use this exception and reduce fire pathways to meet exception 1 using the rest of the building to justify this.

This is an example of a multi family home with proper unit separation fire walls. The designer was able to use the rest of the building to justify reducing the fire setbacks to only include 12" on either side of any horizontal ridge.

This is how the fire setbacks will appear on the plans. 

• Note that a 3' path is still needed around and to any heat vent. The designer was careful to detail this.

OVERVIEW

• If we meet these requirements, only 1' offset on each side of the ridge are needed

  • • Roof is pitched

    • There is an intersecting adjacent roof section free of PV.

    • If we do not meet these the requirements listed above, then we will need to default to provide 36" pathways on three sides of each PV array.

  • Next, we need to find the total area of the roof occupied by PV. 

    • If over 25%, we will need a single 3' pathway from the eave to the ridge in addition to the 12" offset at the ridge.

    • If 25% or less, we only need the 1' offset on both sides of the ridge and no additional pathways will be needed.

    • Just like with 2018 IFC, we need to use the plan view area. Round down to about 23% for this area requirement.

  • A 36" clearance must be maintained around heat vents, smoke stacks and mechanical units as well as a 36" path to these obstructions from a low eave.