What do US building codes say about penetrations in fire-resistance-rated assemblies, and is a firestop log required?

Short answer: Where the International Building Code (IBC) is adopted, penetrations of fire-resistance-rated walls and floors must be protected by approved firestop systems tested to ASTM E814 or UL 1479. The model codes we reviewed do not name a firestop log, but they do require records that a log provides. Requirements depend on the locally adopted code and the AHJ.

Which building codes apply to penetrations in the United States?

There is no single national building code. States and local jurisdictions adopt model codes, mostly the International Building Code (IBC) and the International Fire Code (IFC) published by the International Code Council (ICC), often on different editions and with their own amendments. The locally adopted code and the Authority Having Jurisdiction (AHJ) decide what applies.

You know the situation: the specification says "per code", the firestop submittal refers to the 2021 IBC and the jurisdiction enforces another edition with local amendments. Before you discuss a detail with the building official, check which edition applies, because section numbers and exceptions can differ.

According to the ICC, the IBC is in use or adopted in all 50 states and the District of Columbia, and the IFC in 42 states. Hospitals and other health care facilities in Medicare and Medicaid must also meet the 2012 edition of NFPA 101, the Life Safety Code, under CMS rules.

Topic	Where to look
Penetrations of rated walls and floors	IBC section 714
Special inspection of firestops	2021 IBC section 1705.18
Owner's maintenance of rated construction	2018 IFC section 701.6
Fire test for firestop systems	ASTM E814 or UL 1479

What does the IBC require for penetrations of rated walls and floors?

The 2021 IBC requires through-penetrations of fire-resistance-rated walls and floors to be protected by an approved penetration firestop system, tested to ASTM E814 or UL 1479 at a minimum positive pressure differential of 0.01 inch of water. Walls need an F rating, while floors generally need both an F and a T rating.

Assembly	2021 IBC section	Required rating of the firestop system
Fire-resistance-rated wall	714.4.1.2	F rating not less than the required fire-resistance rating of the wall
Floor or other horizontal assembly	714.5.1.2	F and T rating of at least 1 hour, and not less than the required rating of the floor

According to UL Solutions, the F rating is the time a firestop system limits the spread of fire through the opening, and the T rating is the time it also keeps the temperature rise on the unexposed side within 325°F above its initial temperature. Both IBC sections contain exceptions, so read the full text of the edition your jurisdiction adopted.

What does "installed as tested" mean on site?

A firestop only carries its rating when the installation matches the tested and listed system: the same type of wall or floor, the same penetrating item, the same annular space, materials and depth. A different sealant, missing mineral wool or a larger opening than listed means the rating no longer applies.

Check the system number in the approved submittal against the penetrating item and assembly.
Where no tested system fits, a manufacturer can issue an engineering judgment based on tested systems; the AHJ decides whether to accept it.
Keep the listing details with the log, because inspectors check the work against them.

When does the IBC require special inspection of penetration firestops?

The 2021 IBC requires special inspection of penetration firestops in high-rise buildings, in buildings assigned to Risk Category III or IV, and in fire areas containing Group R occupancies with an occupant load greater than 250. The special inspector reports to the building official, and ASTM E2174 describes how installed firestops are inspected on site.

The owner or the owner's authorized agent, not the contractor, employs the special inspection agency (2018 IBC section 1704.2), so the inspection stays independent from the installer whose work it checks.

Does the fire code require owners to maintain firestopped penetrations?

Yes, where the IFC is adopted. The 2018 IFC requires the owner to keep an inventory of required fire-resistance-rated construction, inspect it visually every year, repair it where it is damaged, altered, breached or penetrated, and keep records of inspections and repairs. Other editions and local amendments can differ, so confirm with the AHJ.

Every renovation or new cable in an existing building can create a new obligation, so facility managers need to know where each penetration is and how it was sealed.

Is a firestop log required by US building codes?

Not as a named document. We found no IBC or IFC section that requires a document called a firestop log. The codes do require approved firestop systems, special inspection reports in certain buildings and, under the IFC, an owner's inventory with records of inspections and repairs. A firestop log keeps those together.

	Required by the model codes?	In practice
Approved, tested firestop systems	Yes, IBC section 714	Basis of design and submittals
Special inspection of firestops	Yes, in the buildings listed in 2021 IBC section 1705.18	Reports go to the building official
Owner's inventory of rated construction	Yes, where the IFC is adopted	Often missing after turnover
Records of inspections and repairs	Yes, where the IFC is adopted	Often the weak spot
A document called a firestop log	Not named	Common way to show the above

Owners and AHJs can require a log. As industry practice, not code, FM 4991 approval and the UL Solutions Qualified Contractor Program audit a firestop contractor's documentation. Ed Controls, quality control and project collaboration software for construction, records these data for each penetration on the drawing, as explained in Firestop log: what goes in it.

Who is this explanation for?

This explanation is meant for professionals who want to know where penetrations sit in the model codes, so they can ask the right questions of the AHJ, the design team and the firestop contractor. It does not replace the adopted code text or the decision of the AHJ.

Suitable for:

Superintendents and project managers
Firestop contractors
Owners and facility managers

Not intended as:

Legal advice or a replacement for a fire protection engineer when designing rated assemblies

Frequently asked questions

Which edition of the IBC applies to my project?
The edition that your state or local jurisdiction has adopted, including its local amendments. Editions differ between jurisdictions, and section numbers can change between editions, so check the adopted codes or ask the building official before you rely on a section number.

What is the difference between an F rating and a T rating?
The F rating is the time a firestop system stops fire from passing through the opening. The T rating is the time it also keeps the temperature rise on the unexposed side within 325°F above the starting temperature. Both come from fire tests under ASTM E814 or UL 1479.

Does every penetration need a T rating?
No. Under the 2021 IBC, firestop systems in fire-resistance-rated walls need an F rating, while systems in floors and other horizontal assemblies generally need both an F and a T rating of at least 1 hour, with exceptions. Always check the edition and amendments your jurisdiction adopted.

Who is responsible for firestops in an existing building?
Where the IFC is adopted, the owner is responsible for maintaining fire-resistance-rated construction, including penetrations, and for keeping records of inspections and repairs. In practice the owner should make sure contractors who work in the building seal every new penetration and that each one is checked and recorded.

Is a firestop log mandatory?
The IBC and IFC do not name a firestop log. They do require approved firestop systems, special inspection in certain buildings and, under the IFC, an owner's inventory and records of inspections and repairs. A log with a photo, location and listed system for each penetration is the most practical way to show this.

Sources

This article explains model codes in general terms and is not legal advice.

Last updated: 12 October 2026