What material can be used for fire blocking?

Author: Joaquin Farrell  |  Last update: Saturday, October 18, 2025

1) 2x nominal lumber 2) ¾” plywood or OSB 3) ½” Drywall or better 4) Mineral wool or Fiberglass batt “securely retained in place” in an approved manner Fiberglass batt used as fireblock must entirely fill the cavity protected and must be packed tightly around any obstruction such as a duct or pipe. R302.

Can OSB be used for fire blocking?

OSB Firestop boards provide load-bearing capacity and fire resistance of building structures and are lighter and stronger than plasterboard. With the same thickness, they achieve similar fire properties as sheathing systems based on the combination of OSB and plasterboard.

What insulation can I use for fire blocking?

Batts or blankets of mineral wool, mineral fiber or other approved materials installed in such a manner as to be securely retained in place.

Can I use foam as fire blocking?

Loctite Fire Block Foam is a specially designed insulating foam to fill gaps and resist the migration of fire and hot gasses in Type V residential (wood frame) construction. This foam is orange in color and is easily identifiable on the jobsite.

What is an alternative to fire foam?

Rather than foam or water, another AFFF alternative is the bevy of dry chemical agents on the market. Most, if not all, dry chemical agents do not contain any PFAS, thus making them environmentally safe. Usually, a dry tank is pressurized, and when activated, the dry chemicals are released via nozzles and piping.

What Materials Can You Use for Fireblocking?

Can spray foam be used as a fire barrier?

This issue is addressed in a report from the National Association of State Fire Marshals. However, just because spray foam manufacturers add fire retardant, it doesn't automatically mean that the product is fire resistant. Fire code requires a 5 or 15 minutes intumescent coating to be painted over the foam.

What is the code for fire blocking?

R302. 11 Fireblocking. In combustible construction, fire-blocking shall be provided to cut off both vertical and horizontal concealed draft openings and to form an effective fire barrier between stories, and between a top story and the roof space.

What is the maximum gap for fire foam?

A: Fire Door Foam has been fire tested to 60 minutes (BS476 Pt20/22: 1987 & BS EN1634-1) in timber and composite doorsets and timber glazed screens. Q: What is the minimum and maximum gaps Fire Door Foam™ can be used? A: The minimum practical width is 5mm and maximum tested gap is 33mm.

What are the best fire insulators?

Mineral wool is noncombustible and can be used in tandem with other forms of fire-resistant insulation. Mineral wool can also refer to glass wool, rock wool, or slag wool. Glass wool in particular can withstand temperatures of up to 1,220 degrees.

Can you use plywood for fire blocking?

Basically, this code states that the product cannot fall out in a fire. For this reason, fireblock such as ¾” plywood is preferable (when practicable) to fiberglass insulation in a variety of circumstances because it is shot into position.

Is OSB a 15-minute fire barrier?

The APA has reported that 23/32” western species plywood or OSB will meet the 15 minute thermal barrier.

Can cement board be used as a fire barrier?

Yes, HardieBacker® 1/4" Cement Board is deemed noncombustible when tested to ASTM E 136 and can be used in conjunction with other noncombustible materials around a fireplace.

Can fiberglass be used for fire blocking?

Glass fiber insulation, when used as fireblocking must be unfaced. Paper-facing is flammable, and would aid in the spread of fire. The insulation must fill the entire cross section of the wall cavity for a minimum height of 16 inches, measured vertically, below the ceiling or soffit drop.

What material is used for fire protection?

This can be done by applying a fire-resistant material, such as mortar, cement, or fireproof paint. Fireproofing is often used on steel structures and concrete to make them more resistant to fire. There are two main types of spray-applied, fireproof paint: intumescent and cementitious.

Can you use pink foam for fire stopping?

Whilst it can sometimes be used to effectively seal small linear gaps, for instance, pink foam has a limited tested scope of application. Therefore, we strongly advise against using it when firestopping service penetrations.

Is blue foam fire resistant?

Blue60 is a specially formulated expanding foam that gives up to 60 minutes fire protection to timber doorsets without the use of additional mastics or sealants. Tested with a range of applications. Suitable for gaps between 7mm & 30mm.

Is fire block foam flammable?

The information herein is not intended for use by non-professional designers, applicators or other persons who do not purchase or utilize this product in the normal course of their business. CAUTION: When cured, these products are combustible and will burn if exposed to open flame or sparks from high-energy sources.

What is the thickness of fire blocking?

8, Item 4, fireblocking shall consist of 2-inch (51mm) nominal lumber, or two thicknesses of 1-inch (25.4 mm) nominal lumber with broken lap joints, or one thickness of 23/32-inch (19.8 mm) wood structural panels with joints backed by 23/32-inch (19.8 mm) wood structural panels or one thickness of 3/4-inch (19.1 mm) ...

Where do you put fire blocking?

8 of the IRC states, “Fire blocking shall be provided to cut off all concealed draft openings (both vertical and hori- zontal) and to form an effective fire barrier between stories, and between a top story and the roof space.” The section goes on to list a number of locations where horizontal and vertical cavi- ties ...

What foam is fireproof?

Flame retardant foams are chemically treated to be slow burning or self-extinguishing when exposed to an open flame. These fabrics can be made from any material, but they must be treated with special chemicals to qualify as flame retardant.

Can expanding foam be used for fire stopping?

Yes, you can. Fire rated foam can expand by 40 times and can be used to seal compartment walls and floors, partitions and fire doors. Fire rated expanding foam typically offers four hours of fire resistance and is tested in accordance with EN1366-4: 2006.

What type of foam is used for fire suppression?

Firefighting foam is a foam used for fire suppression. Its role is to cool the fire and to coat the fuel, preventing its contact with oxygen, thus achieving suppression of the combustion. Firefighting foam was invented by the Moldovan engineer and chemist Aleksandr Loran in 1902.

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