Easy as Foam: A Beginner's Guide to Spray Foam Sealants

What is Spray Foam Sealant?

When you think of spray foam, you might imagine a professional insulating a new home under construction. Foam insulation is commonly used in building projects to create a thermal and acoustic barrier over large areas. Meanwhile, foam sealants, primarily made of expanding polyurethane, create airtight and weatherproof barriers that seal gaps to block air, moisture, and pests for a wide range of applications around the home.

Foam sealants come in many versatile, easy-to-use formats and formulas for homeowners and professionals. Whether filling gaps around windows, sealing cracks in walls, or seeking to improve your home's energy efficiency, foam sealants provide a flexible, long-lasting solution. Their durability and adaptability make them a go-to material for construction projects and simple home improvement tasks alike.

Common Applications of Spray Foam

Foam sealants are incredibly versatile and can be used in various applications inside and outside the home. Their expanding properties allow them to fill gaps and cracks of varying sizes, making them ideal for numerous projects. Below are some of the most common ways homeowners and professionals alike use foam sealants:

• Insulating Rim Joists: Rim joists are located where the floor meets the foundation walls, and they can be a major source of air leakage in homes. Foam sealants are ideal for filling gaps in these areas, preventing drafts and improving overall energy efficiency by keeping tempered air inside the house.
• Sealing Windows & Doors: Gaps around window and door frames are notorious for letting in drafts. Foam sealant can easily be applied around window and door casings to stop air leaks, improve insulation, and prevent moisture from entering, enhancing comfort and lowering energy bills.
• Filling Wall Penetrations: Areas where pipes, wires, and vents penetrate walls are often left unsealed, leading to significant heat loss and even pest infestations. Foam sealant is ideal for filling these gaps, as it expands to seal off irregularly shaped holes.
• Sealing Exterior Gaps & Cracks: Foam sealant effectively fills gaps and cracks in a home's exterior, such as around foundations, siding, or rooflines. These gaps can allow moisture and pests to enter, potentially causing severe damage over time. Sealing exterior gaps protects your home's structure and keeps outdoor elements out.
• Basements & Crawl Spaces: Moisture problems frequently occur in basements and crawl spaces because of cracks or gaps in the foundation or along the walls. Foam sealants are perfect for sealing these areas to stop water from getting in, preventing humidity buildup and mould growth. By keeping moisture out, foam sealant can help maintain a dry, healthy living environment.
• Landscaping Projects: Foam sealants are also helpful for outdoor projects, such as securing rocks in a garden bed or stabilizing landscape features. Their expanding nature helps to fill voids, providing added stability and reducing movement in outdoor structures. Foam can be used to set stones, secure fence posts, or fill gaps around retaining walls.
• Attics & Rooflines: Sealing gaps in attics, around rooflines, and along eaves can prevent air leaks, reduce energy costs, and improve your home's overall insulation. Foam sealant is especially useful in hard-to-reach areas where traditional insulation materials may be challenging to install. Expanding foam provides a complete seal in these challenging spaces by filling cracks and crevices.
• HVAC Systems: Ductwork and other HVAC components often have gaps where air can escape, reducing the system's efficiency and making it work harder. Foam sealants can be used to seal joints and seams in ducts. This ensures that air moves efficiently through the system and reaches the intended areas of the home, improving the performance of the HVAC system and lowering energy costs.
• Pest Control: Foam sealants are effective at blocking entry points for insects, rodents, and other pests. You can prevent pests from finding their way inside by applying foam in small cracks and crevices around the home, such as in the foundation or attic. The foam expands to fill spaces, creating a durable barrier that pests cannot easily chew through or bypass.

Compatible Surfaces for Foam Application

Spray foam sealants adhere to a variety of surfaces, making them suitable for multiple substrates. However, the performance of foam sealants can vary based on the material to which they are applied. Common substrates include:

• Wood: Foam sealants bond well to wood surfaces, making them ideal for sealing gaps in framing, subfloors, and joists.
• Concrete and Masonry: They can seal cracks in concrete walls, foundations, and around masonry openings, providing both insulation and moisture protection.
• Metal: Foam sealants adhere to metal surfaces like HVAC ductwork, sealing gaps and improving insulation. However, be cautious of rust-prone areas.
• Drywall and Plaster: Foam can fill cracks around windows and doors in drywall or plaster walls, preventing air leaks.

Exploring Foam Sealant Varieties 

Single-Component Foam Sealants

Single-component (or one-component) foam sealants are pre-mixed and ready to use, making them perfect for most household and DIY projects. They cure by absorbing moisture from the air and are available in various formats:

Straw Foam

Straw foam is the most common type, featuring a nozzle attached to the can for direct application. It's great for quick fixes and small gaps. This option is typically user-friendly and doesn't require special equipment.

Gun Foam

Gun foam sealants are applied using a foam dispensing gun, providing greater control over the bead size and flow rate. This type is ideal for larger projects or areas requiring precision, such as around window frames or narrow gaps.

Canister Foam

Canister foam is a higher-volume option, typically used in larger jobs requiring more foam. It offers an extended reach and coverage compared to smaller cans, making it a good choice for more extensive insulation or sealing projects.

Two-Component Foam Sealants

Two-component (or two-part) foam sealants consist of two separate chemicals that react when mixed to create a dense, durable foam. These are more powerful than single-component foams and are typically used for larger-scale, professional-grade projects.

Foam Kits

Foam kits are designed for high-volume, high-performance applications, such as insulating large spaces like attics, basements, or crawl spaces. Due to their strength and complexity, two-component foam kits are intended for professional use only and require special handling and equipment for safe application.

Preparing for Spray Foam Application

Tools & Materials

Before beginning a spray foam project, gather all the necessary tools and materials to ensure smooth application. The exact tools will depend on the type of foam you're using, but the essentials typically include:

• Foam Sealant Can or Canister
• Straw Applicator or Dispensing Gun (depending on foam type): Allows for precise application
• Gloves: Shields hands from direct contact with foam chemicals
• Safety Glasses: Protects eyes from potential splashes or foam particles
• Respirator or Facemask: Prevents inhalation of fumes during application
• Drop Cloths or Plastic Sheeting: protects surrounding surfaces from accidental overspray
• Utility Knife or Foam Cutter: Used to trim away excess foam after it has cured
• Ladder or Step Stool: Provides access to hard-to-reach areas during application

Safety Precautions

Spray foam application requires adherence to specific safety guidelines to protect yourself and your surroundings. Always consult the Material Safety Data Sheet (SDS) and Technical Data Sheet (TDS) for your specific foam product. Foam sealants contain chemicals that can be harmful if not handled properly. Here are essential safety precautions to follow:

• Wear protective gear: Always wear gloves, safety goggles, and a respirator when working with spray foam. This protects your skin, eyes, and lungs from chemical exposure.
• Ventilate the work area: Spray foam releases fumes during application, which can be harmful in enclosed spaces. Work in well-ventilated areas, and consider using fans to direct airflow.
• Protect surrounding surfaces: Use drop cloths or plastic sheeting to shield nearby surfaces from foam overspray.
• Avoid ignition sources: Foam sealants are flammable during dispensing and until fully cured. Turn off all ignition sources, such as open flames, pilot lights, or electrical sparks, and keep away from heat sources while applying.

Surface Preparation

For the best adhesion and performance, ensure the substrate is clean, dry, and free from dust or debris. Remove dust, dirt, grease, or other foreign materials that could affect bonding.

Applying Spray Foam

Step-by-Step Guide for Applying Straw Foam Sealant

Specifications based on BARRIER Multi-Project Foam Sealant:

1. Ready the Can: Attach the straw adapter to the canister; carefully screw the trigger assembly onto the valve in a clockwise direction. Then, shake the canister vigorously for 30 seconds to mix the foam components thoroughly.
2. Test the Foam: Hold the can upside-down and slowly squeeze the trigger until foam begins to dispense. Before starting your project, practice applying foam on a piece of scrap material to get used to the flow and expansion.
3. Apply the Foam: Hold the can upside-down during application. Fill gaps no more than 1/3 full to allow room for the foam to expand. Be careful not to overfill the space, as the foam will continue to expand after dispensing (unless otherwise indicated). Note: The foam will dispense for a few seconds after releasing the trigger, so keep the straw moving to avoid overfilling. Apply foam in areas with at least 40% relative humidity for best results.
4. Cleanup & Curing: For wet foam on the skin, clean immediately with a dry rag—do not use water, as it accelerates curing. For uncured foam on surfaces, use foam cleaner or acetone to clean. The foam will become tack-free in about 30 minutes and fully dry within 4 hours. After curing, excess foam can be trimmed or sanded as needed. If foam dries on the skin, apply petroleum jelly, wear plastic gloves, and wait an hour. Then, wipe off with a clean cloth. Repeat if necessary.
5. Storage & Reuse: To stop and restart the canister up to 3 weeks later, bend the straw back and attach it to the knob on the dispensing trigger. Store the can upright below 32°C (90°F) and above freezing. To reuse, cut off the end of the straw to remove any cured foam, shake the can well, and dispense as directed. The second straw provided allows reuse for up to 6 weeks.

Step-by-Step for Applying Gun Foam Sealant

Instructions specific to TOUCH 'N FOAM® Professional All-Purpose Polyurethane Foam Sealant:

1. Attach Foam Can to Gun: Apply petroleum jelly to the gun basket for easier attachment. While pointing the gun in a safe direction, depress the trigger and attach the gun to the can. Do not over-tighten the gun onto the can.
2. Test the Foam: Before starting, practice dispensing foam onto scrap material.
3. Apply the Foam: Hold the can upside-down during application, like with straw foam. Fill gaps no more than 1/4 full to allow room for expansion; less than 1/3 full is recommended for straw foam.
4. Replace the Can: When empty, point the gun in a safe direction, depress the trigger, and quickly remove the can. Spray the basket with foam cleaner and immediately replace the empty can with a new one to avoid the foam hardening inside the gun.
5. Cleanup & Curing: For wet foam on the skin, clean immediately with a dry rag—do not use water, as it accelerates curing. For uncured foam on surfaces, use foam cleaner or acetone to clean. The foam will be tack-free in about 10 minutes at 50% relative humidity, offering a faster curing time than straw foam, which takes 30 minutes. After curing, excess foam can be trimmed or sanded as needed. If foam dries on the skin, apply petroleum jelly, wear plastic gloves, and wait an hour. Then, wipe off with a clean cloth. Repeat if necessary.
6. Storage & Reuse: Remember to turn the gun's flow control knob to the closed position before storing. Store the gun with the can still attached in an upright position, below 33°C (90°F) and above freezing. The maximum storage time is 15 days. When cleaning, use polyurethane foam cleaner to flush the applicator.

Step-by-Step for Applying Canister Foam Sealant

Instruction for TOUCH 'N FOAM® Professional One-Component Low GWP 10lb Foam Sealant:

1. Check the Foam: Before starting your application, check the expiration date on the carton to ensure the product is current. Shake the cylinder about 10 times while standing upright. Ensure that the chemical contents are at a temperature between 21°C and 32°C (70°F and 90°F) before dispensing.
2. Prepare & Test Applicator: Attach the hose to the wand and cylinder valve with the applicator in the closed position. Tighten the fittings with an open-end wrench, being careful not to over-tighten. Open the cylinder valve and move the wand lever to the open position, regulating the flow rate with the lever. Always dispense foam on scrap material first to practice.
3. Apply the Foam: Fill voids about 40% full, allowing the foam to expand.
4. Cleanup & Curing: If wet foam contacts skin, clean it immediately with a dry rag—do not use water, as water accelerates curing. Uncured foam can be cleaned from most surfaces with foam cleaner or acetone. If the foam dries on the skin, apply generous amounts of petroleum jelly, put on plastic gloves, and wait for one hour. With a clean cloth, firmly wipe off the residue and repeat the process if necessary. After curing, excess foam can be trimmed or sanded as needed and must be removed from surfaces mechanically.
5. Storage & Disposal: Keep the container tightly closed in a cool, well-ventilated area. Store the can upright below 33°C (90°F). Avoid exposing containers to conditions that may damage, puncture, or burst them. Dispose of leftover material and containers per local regulations.

Factors Affecting Foam Cure Time

The time it takes for foam sealant to harden can change based on a few things. Warmer temperatures, around 21°C to 32°C (70°F to 90°F), make it harden faster. More moisture in the air can also speed up the process. On the other hand, using foam in colder temperatures or low humidity can make it take much longer to harden, which means it might not harden completely and won't work as well. Also, air movement can help it harden faster, but keeping it in a still, enclosed space can slow it down.

Incorporating spray foam sealant into your home improvement projects can significantly enhance insulation, energy efficiency, and pest control. By understanding the different types, applications, and proper techniques, you can effectively tackle gaps and cracks around your home. Remember to prioritize safety and surface preparation for the best results. With the right approach, you'll enjoy the benefits of a more comfortable and well-protected living space. Happy sealing!

Learn More