Nelson Firestop Brick

Prevents Through-Penetration of Fire

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What's special about this firestop material?

  • Soft, pliable, intumescent material fits snugly where you need firestop protection and will expand quickly in the event of a fire
  • Protects against the passage of flame, noxious gas and smoke right from the package; nothing to mix, pour or build
  • High fireproof rating (up to 2-hours of fire protection) and excellent heat insulation give you time to extinguish flames and safely protect your valuables
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Firestop Brick is ideal for applications where there might be a need to re-penetrate an area, and is easy to re-position. When the brick comes into contact with fire, the brick material expands within the opening, forming a solid char that prevents through-penetration of the fire for up to 2 hours. Because of its versatility, this economical, durable, labor-saving firestop material is ideal for cable or cable tray penetrations.

Part #DescriptionDimensionsPackageWeightPrice
NFS-AA834Nelson Firestop Brick2" H x 5" W x 8" L6 per pack1.48 lbs
Manufacturer Direct

For maximum effectiveness, install the brick into a clean opening (no grease, dirt or other sediment). Unless otherwise specified, pack the bricks into openings and around penetrating items, being sure to fill in any empty spaces. The brick should always lay in the center of the opening, and can be cut to accommodate the space.

Nelson Fire Brick is designed to seal large penetrations or just a single hole.

  • Elastomeric properties make it easy to install, and it's repenetrable for those times when you need to shift, repair or reposition your firestop
  • Non-shrinking material assures you no gaps will suddenly “appear” once the job is finished
  • Asbestos-free, non-toxic product is safer for both the installer and other people in the vicinity
  • Will not lose its effectiveness as it sits on your shelf waiting to be used - excellent shelf life
  • One year manufacturer warranty


firestop brick installationApplications include interim or permanent seal fire protection through:


NOTE: This product is not combustible and does not contribute to the intensity of a fire. When involved in a fire, this material may decompose and produce irritating vapors, acrid smoke, and toxic gases.

If heated to decomposition, can produce CO, NO, HCN, HCI and or HF

Keep out of reach of children.

Wash hands after handling and before smoking or eating.

This product is regarded as an “article” as defined under OSHA Regulation 29 CFR 1910.1200 (c). Under normal working conditions and use, the physical form of this product precludes exposure to a hazardous chemical.


Part # NFS-AA834
Package 6 bricks
Physical State Solid
Appearance Charcoal Gray
Relative Vapor Density (air = 1) n/a
Evaporation Rate (n-BuAc = 1) n/a
Solubility in Water Not Soluble
Vapor Pressure, mm Hg @ 20° C n/a
pH n/a
Odor None
Density 0.51 g/cm³
VOC Content n/a
Stability Stable
Weight 1.48 lbs
Dimensions 2" H x 5" W x 8" L
Intumescent Activation Temperature  > 300° F
Asbestos Filler none
Test Compliances ASTM E-814, UL 1479, UL W-L-4061, UL W-J-4058
Storage / Handling Stored in dry, covered locations
Shelf Life No indication of limitations
Flash Point  > 800° F / 426° C


Firestop Brick MSDS (PDF)

General Installation Instructions

Refer to the actual installation guide in the Nelson catalog or the applicable system in the UL Fire Resistance Directory.
For Cable Tray application:

  1. Make sure area is clean. There should be no foreign particles on cable tray and cables
  2. Apply Nelson Firestop Putty (separate item) within spaces between cables on both sides of wall
  3. Install Bricks with 5 inch dimension projecting through opening. Polyethylene film is applied to top and bottom surfaces of brick to aid in ease of installation
  4. Cut Bricks as necessary to provide a tight fit between opening and cable tray
  5. Stack Bricks in rows to completely fill all remaining space and press the top row tightly for a secure fit.






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Questions & Answers


Is there a typical life span once bricks are installed in a cabletray penetration?

Asked by Anonymous user on 07/11/2017 10:13 AM

  • - Hello, The Nelson Firestop brick has a life span of 15-20 years depending on the environment it is installed.

    Anonymous user on 07/11/2017 3:29 PM

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