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Fire Protection - 2015 IRC Code Highlights

Fire Rated Assemblies

Two-Family Dwellings

Dwelling units in two-family dwellings must be separated from each other by wall and floor assemblies having a minimum 1- hour fire resistance rating. Fire resistance shall run from foundation to underneath the roof sheathing. Note: If doing a remodel on a two-family dwelling and the common wall between the two units is disturbed, your local jurisdiction may require a minimum of 5/8” Type X drywall to be applied to the common wall of the side being remodeled. (R302.3)


  • Separation: Townhouses are generally required to be provided with a shaft wall or demising wall, separating each individual unit from adjacent units. Each separation wall shall have a 2-hour fire-resistance rating for non-sprinklered units or a 1-hour fire-resistance rating for sprinkled units. (Note: Pennsylvania requires all new townhomes to have a sprinkler system, so the 2-hour assembly would mainly affect remodels in existing townhomes constructed without a sprinkler system already installed.) [A1]

  • Firewall: The rated firewall must extend from the foundation to underneath the roof sheathing and must also run the full length of the building along the lot line. This includes any walls that extend past an adjacent unit due to an offset in the building layout. In fact, any walls on a house within 5 feet of the lot line – except those oriented perpendicular to the lot line – must have a minimum of 1-hour fire protection, rated for fire exposure from either the inside or outside of the wall.

  • Parapets: Firewalls are required to extend continuous from the foundation to the top of a fire-rated parapet, which must extend 30” above the common roof line (where adjacent roofs are the same height), 30” above the lower roof line (where adjacent roofs are less than 30" in height difference), or to the roof decking of the higher roof (where adjacent roofs are 30"+ inches in height difference). However, as an exception to constructing a parapet in the first two cases, the firewall may also be terminated at the underneath of the higher roof, as long as either fire-rated roof sheathing or 5/8” Type X drywall below the roof sheathing is provided for a width of 48” on either sides of the firewall. Roof openings or penetrations such as plumbing or ridge vents are not permitted within 48” of firewalls. (R302.2.1, R302.2.2)

Garage and Dwelling Protection

Openings between the garage and residence need to be equipped with solid wood doors not less than 1 3/8” in thickness, solid or honeycomb-core steel doors not less than 1 3/8” thick, or a 20-minute fire-rated door. (R302.5.1) Note: Per PA UCC, a door between the garage and residence is not required to have self-closing hinges.

Emergency Escape Openings

Requirements: Emergency escape and rescue openings are required in basements, habitable attics and every sleeping room. The total clear opening size needs to be a minimum 5 sq ft for windows at or below grade level and not less than 5.7 sq ft for windows above grade level. However, not all opening shapes are easy to crawl through, regardless of area (for example, a 12’ by 6” opening), so the net clear opening height must not be less than 24” and the net clear width not less than 20” for all egress windows. (R310.1.1)

Under Decks and Porches: All rescue openings and emergency escapes under decks and porches are required to have a minimum of 36” of clear height between the ground and the deck or porch to allow adequate room for someone to pass underneath out to an open area. (R310.2.4)

Smoke Detectors

Renovations: Since smoke and CO detectors are life-safety devices, ensuring the building is properly equipped with them must be part of a contractor’s scope of work for most residential alterations, repairs, or additions requiring a permit (R314.2.2). However, PA UCC permits detectors to be battery operated where installed in an existing, finished area.

Requirements: A smoke detector is required on all levels, in all sleeping units and within a close proximity outside of sleeping units. For new construction, all smoke detectors are required to be hardwired and interconnected. Bluetooth is now accepted for connectivity.

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