Akfix 840 Fire Block Spray Foam - Fire Resistant Expanding Foam

In this review the Akfix 840 Fire Block Spray Foam is examined as a practical option for builders, remodelers and home DIYers who need a fire-rated sealant for gaps and penetrations. The single biggest reason to consider it is its Class A fire rating and fire-retardant formulation, which provide an added layer of protection around windows, doors and service penetrations. The reviewer found it useful for large-cavity filling and long-term adhesion, while noting there are tradeoffs in spray handling that affect ease of application.

Key Features

• Fire-Resistant Foam: Designed to slow flame spread and add protection to residential and commercial openings where fire resistance matters.
• High Expansion: Expands significantly after application to fill large gaps and cavities, reducing the number of cans needed for wide voids.
• Strong Bonding: Adheres well to common materials such as wood, concrete and metal for long-lasting seals around frames and penetrations.
• Paintable Finish: Cured foam can be painted or coated to improve UV resistance and blend with exterior or interior surfaces.
• Class A Fire Rated: UL-certified and ICC-approved for enhanced safety in both residential and commercial installations.

Who It's For

This product is aimed at professionals and competent DIYers who need a fire-rated polyurethane foam for sealing around windows, doors, pipes and electrical fixtures. It is especially useful when a high-expansion material is needed to fill deep voids quickly and when a paintable finish is desired for final appearance.

Those who prefer very precise bead control or who are inexperienced with low-flow spray foams should consider alternatives or practice first, because some users report variability in sprayability and handling that can make neat application more challenging.

Pros & Cons

Pros

• Class A fire rating offers genuine fire-blocking benefits in key installations.
• High expansion reduces material waste by filling large cavities effectively.
• Strong adhesion to wood, concrete and metal supports durable seals.
• Paintable once cured, allowing UV protection and aesthetic finishing.

Cons

• Sprayability is inconsistent for some users, making application harder than expected.
• Mixed feedback on ease of use and perceived value means it may require skill to get the best results.

Specifications

Product	Fire block spray foam
Packaging	12 cans per pack, 12 oz each
Fire rating	Class A (UL-certified, ICC-approved)
Color	Orange
Main material	Polyurethane expanding foam
Applications	Gap filling, insulation and sealing around windows, doors and penetrations

Our Verdict

The Akfix 840 Fire Block Spray Foam is a solid choice when fire resistance and high expansion are priorities; it bonds well to common building materials and accepts paint after curing. Professionals and experienced DIYers who can manage its spray characteristics will find it good value for sealing large gaps and increasing fire safety, while novice users may want to practice to avoid messy application.

Frequently Asked Questions

Is this foam paintable?
Yes. Once fully cured the foam can be painted or coated to improve UV resistance and appearance.

Can it be used around electrical fixtures?
Yes. It is designed for sealing around electrical fixtures and pipe inlets, but follow local codes for firestopping details.

How many cans are included?
The product is supplied as a 12-pack of 12 oz cans for larger projects and repeated use.