Expanding Foam

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Expanding foam is a versatile material that has a wide range of uses in construction, DIY, and other applications. It is a type of polyurethane foam that expands when it comes into contact with air, creating a lightweight and durable material that can be used for a variety of purposes.

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What Is Expanding Foam?

Expanding foam is a type of polyurethane foam (PU foam) that is designed to expand when it comes into contact with air. It is typically sold in a canister or spray bottle, and can be applied to a variety of surfaces, including wood, metal, and concrete. 

When the foam is exposed to air, it expands to fill gaps and crevices, creating a lightweight and durable material that is ideal for sealing and other applications.

With its expansive nature, expanding foam filler can be used in tricky places that would otherwise be inaccessible with ordinary filler.

Upon curing, most spray foam insulation can be customised to accommodate any space - from cutting and sanding down to painting over.

We sell expanding foam products suitable for use with foam guns as well as a handheld variety. 

For all of our general construction building materials and more categories, please navigate via our handy headers and search bar. 

How Does Expanding Foam Work? 

Expanding foam works by using a two-part chemical reaction to create a foam that expands and hardens. 

The two components of the foam are stored separately in the canister or spray bottle and are mixed together when the foam is sprayed onto a surface. 

As the foam is exposed to air, it begins to expand and fill the surrounding area, creating a lightweight and durable material that can be shaped and trimmed as needed.

Expanding Foam Applications

With the right type and brand, expanding foam can establish a resilient seal that effectively guards against heat, noise, and moisture.

Let's take a look at its most common applications below: 

  • Filling gaps and cavities 
  • Fastening components together via adhesion
  • Sealing door frames 
  • Sealing window frames
  • Quelling draughts

Frequently Asked Expanding Foams Questions

How Much Will PU Foam Expand? 

Expansion of the product depends on whether it is Foam Gun Grade or Hand-Held. 

With Hand-Held foam, you can expect a growth rate of 150-200%, meaning that your joint/cavity needs only be filled with 30-40% for adequate coverage.

Gun-Grade foam has the potential to expand by 50-100% when applied, requiring a minimum of a 50% fill for each gap or void. 

Expansion rate is also dependent on temperature and humidity levels. 

How Long Does It Take For Expanding Foam To Dry? 

The drying time for expanding foam (the time it takes for the foam to have fully cured) can vary depending on the brand and the temperature and humidity of the environment. Generally, it can take anywhere from 30 minutes to several hours to dry completely.

Does The Canister Need To Be Shaken During Use?

Give the canisters a thorough shake before you begin to spray and during application; this will ensure that you receive steady levels of pressure and that the propellant is adequately mixed. 

Does Water Facilitate Expanding Foam?

To ensure the foam cures evenly, lightly mist it with water after cleaning the area. Expanding foam needs a certain amount of moisture for proper curing.

Please note however that you do not want to wet the area, you simply want to mist it. 

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