Quick – Durable – Cost-effective Large Wall Crack Repair with PU Expanding Foam

In the construction industry as well as in the field of repair – finishing works, the appearance of large cracks and gaps on walls is inevitable, especially in cement, concrete, and mortar structures due to the effects of time, environment, or mechanical impacts. Addressing these cracks not only ensures aesthetics but also plays an important role in maintaining structural durability, preventing water infiltration, providing thermal insulation, and extending the service life of the building.

1. Learn how to use PU Foam to effectively repair large wall cracks

Fanxifoam and Selsil Foam – modern expanding foam adhesives, belonging to the PU (polyurethane) Foam group – are the optimal solution for repairing and filling large wall cracks. The product is applied using the included plastic nozzle or a specialized foam gun to inject foam into cracks. When exposed to air, the foam will expand and harden, forming a strong adhesive layer with excellent thermal insulation, soundproofing, and waterproofing properties on various building surfaces such as concrete, brick, stone, wood, metal… After completion, the foam surface can be trimmed, painted, or plastered, restoring and enhancing the quality of the wall as before.

In other words, using Fanxifoam and Selsil Foam to repair large wall cracks is a process that takes advantage of the automatic expansion and superior adhesion of PU Foam to quickly fill large gaps, enhance protection efficiency, and extend the durability of construction works, while effectively preventing water infiltration, moisture, or heat loss through cracked wall sections.

2. Composition and chemical properties of PU Expanding Foam

Fanxifoam and Selsil Foam expanding foam adhesives are primarily made from polyurethane (PU) – a thermosetting polymer synthesized from polyol and isocyanate. When exposed to air humidity or moisture from the wall surface during application, the PU compound reacts to form closed-cell foam that expands and quickly hardens into a material with high adhesion and mechanical durability.

Outstanding characteristics:

– Powerful expansion: The expansion ratio reaches about 25 – 40 times the initial volume, quickly filling cracks and cavities with only a small amount of foam.

– Versatile adhesion: PU Foam adheres firmly to many construction surfaces such as concrete, cement, brick, stone, metal, aluminum, wood, and plastic… (does not adhere to PE, PP, and Teflon).

– High elasticity and stability:

• Fanxifoam: Stable expansion, minimal shrinkage, does not crack after curing, suitable for cracks requiring high airtightness.
• Selsil Foam Premium Flex: Good elasticity and recovery, ideal for gaps subject to thermal movement, vibration, or frequent expansion and contraction.

– Waterproofing, thermal and sound insulation: Closed-cell foam creates a barrier against water and air while reducing heat transfer and minimizing noise.

– Safe & durable: The product contains no CFC/H-CFC, withstands humid environments, UV rays, and a wide temperature range from -40°C to +90°C (depending on the product line).

With these chemical and physical properties, Fanxifoam and Selsil Foam are ideal solutions for sealing, reinforcing, waterproofing, thermal insulation, and soundproofing in various construction applications, helping increase durability, tightness, and aesthetics for the project.

3. Outstanding advantages of PU Expanding Foam in repairing large wall cracks

Why should you use Fanxifoam and Selsil Foam expanding foam from Thuận Thiên Thành to repair large wall cracks? Here are the outstanding advantages:

3.1 Exceptional expansion and filling ability

Fanxifoam and Selsil Foam have a powerful expansion ability, increasing volume up to 25 – 40 times compared to the initial amount. Thanks to its self-expanding properties, the foam easily penetrates all gaps, even hard-to-reach places that traditional mortar or cement paste cannot handle. Once cured, the foam layer bonds tightly to the surface, completely eliminating voids and minimizing water infiltration and cracking over time.

3.2 Easy application – time-saving

Using Fanxifoam and Selsil Foam does not require complicated techniques. The installer only needs to clean and moisten the crack, attach the can to the foam gun or use the included nozzle, then inject the foam. Surface drying time is quick, only about 10 – 15 minutes, and trimming or further finishing can be done within 20 – 30 minutes. Fanxifoam comes with a convenient nozzle, while Selsil Foam can be used with both the nozzle and foam gun, suitable for both professional projects and household repairs.

3.3 High durability and longevity

After curing, the foam layer has excellent adhesion, resists moisture and extreme temperature fluctuations, and does not shrink or crack. Selsil Foam Fire Resistant line even has B1 fire resistance certification, withstanding fire for up to 240 minutes, enhancing the safety of the project. All products are UV-resistant and do not age quickly under weather conditions.

3.4 Excellent thermal and sound insulation

With a closed-cell structure, Fanxifoam and Selsil Foam help prevent heat loss, reduce sound transmission, and effectively waterproof. This not only improves living space quality but also contributes to energy savings for buildings.

3.5 Flexibility and versatile applications

Fanxifoam and Selsil Foam are used in a wide variety of construction applications, from sealing wall cracks, door gaps, and window frames to filling technical holes and voids on ceilings, floors, partitions, or cold storage areas. Fanxifoam has stable expansion, suitable for gaps requiring absolute tightness, while Selsil Foam is highly elastic, ideal for joints that expand, contract, or vibrate.

3.6 Optimize construction costs

Compared to traditional cement plastering or mortar filling, using Fanxifoam and Selsil Foam significantly reduces material and labor costs. The ability to fill gaps quickly, durably, and minimize repeat damage helps investors save on long-term maintenance costs.

4. How to apply Fanxifoam & Selsil Foam effectively

Fanxifoam and Selsil Foam are the ideal solutions to fill gaps and large cracks inside or outside the building, making the surface stronger and more aesthetic. To achieve the best results, follow the steps below:

4.1 Surface preparation and cleaning

First, remove all dirt, grease, excess material, or excessive moisture at the application site. Also, measure the size and depth of the crack to estimate the required amount of foam, avoiding excess or shortage during the process.

4.2 Shake the product well before use

Shake the Fanxifoam or Selsil Foam can vigorously about 20–30 times to ensure the mixture inside is thoroughly blended. Do not forget to check the expiry date and product condition; never use expired or abnormally swollen or leaking cans.

4.3 Prepare suitable tools

There are two popular application methods:

– Using the included nozzle: This is the simplest method, suitable for small household jobs. However, the amount of foam sprayed is hard to control and may lead to waste.

– Using a foam gun: This method is suitable for professionals or applications requiring high precision. Using a gun helps save foam and better preserve the remaining product. After application, clean the gun immediately with cleaning solution to prevent hardened foam inside the tube.

4.4 Inject foam into the crack

When applying, hold the can upside down and insert the nozzle or gun deeply into the crack. Spray from the inside out, from bottom to top, and only fill about 70% of the crack as the foam will expand to fill the remaining volume. Avoid spraying too quickly or filling completely at once to prevent voids.

4.5 Finish the surface and trim the excess

Wait for the foam to expand and fully cure (average 20–30 minutes depending on environmental conditions). Then use a knife or scissors to remove excess foam protruding outside. If foam spills on finished surfaces, clean it immediately with alcohol, acetone, or a specialized solvent before it hardens.

4.6 Clean application tools

When using a foam gun, clean it thoroughly with specialized cleaning solution immediately after application. This removes leftover foam inside the gun, keeps the gun durable, and ensures proper functioning for future use.

5. How to properly store PU Expanding Foam

To ensure the best quality of Fanxifoam and Selsil Foam during use and long-term storage, customers should note the following:

– Store the product in a dry, cool place away from direct sunlight. The ideal storage temperature is between 5 – 25°C. Do not expose the product to heat sources above 50°C as it is a pressurized container and may pose a risk of explosion.

– After use, tighten the cap or nozzle. This prevents foam from contacting air, avoiding hardening inside the can and waste.

– For products used with foam guns, clean the gun immediately after application. Use specialized cleaning solution to remove residual PU foam inside the gun, ensuring it remains unclogged and functional.

– Always check the expiry date before use. Never use expired products, swollen cans, deformed cans, or products showing signs of hardened foam inside.

– Store safely, out of reach of children and away from strong heat sources. Do not puncture, smash, or burn used cans as they may be dangerous.

6. Thuận Thiên Thành – Reliable silicone & PU expanding foam solutions for every project

Thuận Thiên Thành always prioritizes clear product origins. All silicone adhesives and PU expanding foam products such as Fanxifoam and Selsil Foam are distributed with full quality certifications and transparent origin information, giving customers complete peace of mind when using them for important construction applications.

In addition, Thuận Thiên Thành stands out with its warranty policy and in-depth technical consulting. Our experienced technical team always accompanies customers from product selection and application guidance to after-sales support.

Another great advantage is competitive and flexible pricing, suitable for all project scales, from large construction projects to small household repairs. Thuận Thiên Thành’s reasonable sales policy helps customers easily choose the optimal solution for each specific need.

Moreover, Thuận Thiên Thành owns a diverse product portfolio that fully meets market demand. In addition to the Fanxifoam and Selsil Foam expanding foam lines, the company also supplies various silicone adhesives, PU-based adhesives, waterproof sealants, etc., serving everything from small cracks to large cracks, waterproofing, soundproofing, thermal insulation, and many other important applications in modern construction.

7. Important notes when using PU Expanding Foam

To ensure safe and effective application when using PU Expanding Foam, keep in mind the following notes:

– Carefully read the instructions on the packaging or consult with a technical specialist before application to ensure the correct process and safety.

– Wear gloves, masks, and protective equipment during the entire application process to avoid direct skin contact or inhaling foam particles. If foam gets on your skin, clean it immediately with a specialized solvent or soap before it hardens.

– Thoroughly clean the surface before injecting foam, removing dust, grease, and standing water. A clean surface increases adhesion and prolongs the durability of the foam.

– Do not use the product in locations frequently exposed to oil, strong chemical solvents, or direct flame without first checking the material’s compatibility.

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