Firestop Product Selection Guide

How to pick the right sealant, collar, putty pad, or pillow for each penetration type

Last updated: April 3, 2026

Overview

Every pipe, conduit, cable tray, and duct that passes through a fire-rated wall or floor creates a hole in the fire barrier. Firestopping restores that barrier to its original hourly rating. The catch is that different penetration types need different products. A sealant that works for metal pipe through concrete won't work for a plastic pipe through drywall, and using the wrong product means a failed inspection and rework.

This guide walks through which firestop product to use for each penetration type, how UL system listings work, and practical installation tips that keep you on the right side of the fire inspector. For a deeper look at inspection requirements and what inspectors check, see the firestop inspection requirements page.

Firestop vs Fireblock

These two terms get mixed up constantly on job sites, but they refer to completely different code requirements, different test standards, and different products. Using the wrong one is a code violation.

Firestopping

Firestopping applies to commercial and multi-family construction where walls and floors carry an hourly fire-resistance rating (1-hour, 2-hour, etc.). It falls under IBC Chapter 7, Section 714. Every penetration through a fire-rated assembly must be sealed with a system that has been tested to ASTM E814 (UL 1479) and is listed in a UL system directory. The products are intumescent (they expand when exposed to heat) and are specifically designed to maintain the rated barrier.

Fireblocking

Fireblocking applies to residential wood-frame construction. It prevents flame spread through concealed spaces like stud cavities, soffits, and drop ceilings. It falls under IRC Section R302.11. The products are tested to ASTM E136 (non- combustibility) and ASTM E84 (surface burning characteristics), not to ASTM E814. Fireblocking does not require a UL system listing or an hourly fire rating.

Tip: If the wall has an hourly fire rating on the drawings, it's firestopping. If you're blocking flame spread through concealed stud bays in a house, it's fireblocking. Different code sections, different products, different inspections.

	Firestopping	Fireblocking
Construction type	Commercial, multi-family	Residential wood-frame
Code section	IBC Chapter 7, Section 714	IRC Section R302.11
Test standard	ASTM E814 / UL 1479	ASTM E136, ASTM E84
UL system listing required	Yes	No
Hourly rating	Yes (must match assembly)	No
Example products	Firestop-814+, collars, putty pads	Fire Seal 136, Fire Caulk 136

Product Selection by Penetration Type

This is the decision point that matters most. The penetration type, the material it passes through, and whether the penetrant is combustible all determine which product you need. Get this right and the inspection goes smoothly. Get it wrong and you're tearing it out.

Penetration Type	Product	Why
Pipes (metal) through concrete/CMU	Firestop-814+ sealant	Intumescent, elastomeric, UL Classified
Pipes (plastic PVC/CPVC/ABS) through concrete/CMU	Firestop-814+ sealant + wrap strip or collar	Plastic melts in fire, needs intumescent expansion to seal the void
Pipes (plastic) through drywall	Firestop collar (CLR series)	Snap-on, no sealant needed, fastest installation
Electrical conduit through fire-rated wall/floor	Firestop-814+ sealant	Fill annular space around conduit
Electrical boxes in fire-rated walls	Putty pads	Non-curing intumescent pads, maintains STC and fire rating
Cable bundles / cable trays through large openings	Firestop pillows + Firestop-814+ at edges	Pillows fill the void, sealant seals the perimeter
Mixed penetrations (multiple pipes/cables)	Mineral wool + Firestop-814+	Pack mineral wool as backing, apply sealant to both sides
Non-rated residential stud cavities	Fire Seal 136 or Fire Caulk 136	Fireblocking, not firestopping. ASTM E136/E84

Watch for this: Plastic pipes through fire-rated assemblies are the most common source of firestop failures. The plastic melts away in a fire, leaving an open hole. That's why plastic penetrations always need an intumescent component (wrap strip, collar, or intumescent sealant) that expands to fill the void where the pipe used to be.

Understanding UL System Listings

A firestop product on its own doesn't have a fire rating. The rating belongs to the tested system, which includes the product, the barrier type, the penetrant, and the installation detail. UL publishes these tested systems in their online directory. Each system has three ratings that matter.

Rating	What It Measures	Why It Matters
F-rating (Flame)	Hours the system prevents flame passage	Must equal or exceed the assembly's fire-resistance rating
T-rating (Temperature)	Hours before unexposed side exceeds 325F above ambient	Required for floor penetrations and some wall systems
L-rating (Leakage)	Air leakage rate in CFM per square foot at ambient and 400F	Relevant for smoke-rated assemblies and hospital occupancies

Tip: Always match the product AND the installation detail to a tested UL system. Using the right sealant with the wrong detail still fails inspection. The UL Product iQ database (iq.ulprospector.com) is searchable by product manufacturer, penetrant type, and barrier material.

For a detailed breakdown of what inspectors look for during firestop inspections, including documentation requirements and common rejection reasons, see the firestop inspection requirements page.

Installation Tips

The best firestop product installed incorrectly is still a code violation. These are the practical details that separate a clean inspection from a rejection.

Fill Depth

Sealant depth must match the UL listing for that system. Most through-penetration listings call for a minimum of 5/8 inch of sealant depth. Going thinner than the listed minimum voids the system. Going thicker wastes material but generally doesn't cause a problem.

Annular Space Limits

Most UL listings max out at 2 inches of annular space (the gap between the penetrant and the edge of the opening). If the opening is oversized, you need a different system listing or you need to reduce the opening size. Stuffing extra sealant into a 4-inch gap around a 1-inch pipe is not a valid firestop.

Backing Material

Most through-penetration systems require backer rod or mineral wool as a backing material before the sealant is applied. The backing controls sealant depth and provides a surface for the sealant to bond to. The type of backing (mineral wool vs foam backer rod) must match what the UL listing specifies.

Color Coding

Firestop products are red or orange by design. This is intentional. It makes firestop installations immediately identifiable on the job site and during inspections. If the inspector can't tell at a glance that firestopping was installed, it slows down the inspection. Don't paint over firestop sealant unless the UL listing specifically allows it.

Documentation

Photo-document each penetration before and after firestopping. Include the UL system number on your documentation. Many jurisdictions require a firestop log that tracks every penetration, the system used, the installer, and the date. Having this ready at inspection time saves everyone time.

Common mistake: Installing firestop sealant without backing material in a through-penetration. The sealant sags through the opening, doesn't achieve the required depth, and fails inspection. Always install mineral wool or backer rod first, then apply sealant to the required depth on both sides.

Specifications Quick Reference

All Everkem firestop and fireblocking products at a glance. Each product is UL Classified and tested to the standards listed. Browse and buy these products in the products section below.

Product	Type	UL Classified	Key Standards	Sizes
Firestop-814+	Intumescent sealant	Yes	ASTM E814, E1966, E84, E90	10.1 oz, 20 oz, 28 oz, 5 gal
Flame Guard 814	Non-combustible sealant	Yes	ASTM E814, E136	10 oz, 28 oz, 5 gal
Wrap Strips	Intumescent wrap	Yes	ASTM E814, E1966	1"x144", 2"x144"
Firestop Collars	Intumescent collar	Yes	ASTM E814	1.5", 2", 3", 4"
Putty Pads	Intumescent pads	Yes	ASTM E84, E90	7"x7"x1/8"
Firestop Pillows	Intumescent pillow	Yes	ASTM E814	2"x6"x9"
Fire Seal 136	Fireblocking caulk	Yes	ASTM E136, E814, E84	10 oz, 5 gal
Fire Caulk 136	Fireblocking caulk	Yes	ASTM E136	10 oz, 5 gal

Tip: Firestop-814+ is the workhorse product for most commercial firestopping applications. It covers the widest range of UL system listings and handles metal pipes, plastic pipes (with wrap strips), conduit, and mixed penetrations. If you're stocking one firestop sealant on the job, that's the one.

Frequently Asked Questions

What's the difference between firestopping and fireblocking?

Firestopping restores fire resistance at penetrations through rated assemblies in commercial construction (IBC Chapter 7). Products are tested to ASTM E814 and must be installed per a UL system listing. Fireblocking prevents flame spread through concealed spaces in residential wood-frame construction (IRC Section R302.11). Products are tested to ASTM E136 and E84. Different code sections, different test standards, different products.

Do I need a firestop collar or sealant for plastic pipes?

Depends on the assembly. Collars are faster for drywall penetrations. They snap on around the pipe and don't require sealant. For concrete or CMU penetrations, sealant with a wrap strip is more common. Check the UL system listing for your specific assembly to confirm which approach is valid.

Can I use regular silicone caulk as firestop?

No. Firestop sealants are tested and UL Classified to specific system listings. Regular silicone has no fire rating, no intumescent properties, and will fail inspection. Always use a product that carries a UL Classification mark and is installed per a tested system.

How do I know which UL system listing to use?

Match your penetration type (pipe size, pipe material, cable type), the barrier type (concrete, drywall, CMU), and the required hourly rating. The UL Product iQ database is searchable online by manufacturer and penetration details. You can also contact the sealant manufacturer's tech support for help identifying the right system number.

Do putty pads go on every electrical box?

Only on electrical boxes in fire-rated wall assemblies. Standard interior walls in single-family homes typically don't need them unless the wall has an hourly fire rating or STC (sound transmission class) requirement. In commercial construction, any electrical box penetrating a fire-rated wall needs putty pads or an equivalent firestop treatment.