Filling external cracks is an important step to prevent further damage to a building and improve its aesthetic appearance. Here's a guide on how to fill external cracks:

1. Safety Precautions:

• Wear Protective Gear: Use safety goggles, gloves, and a mask to protect yourself from dust and any chemicals involved in the process.
• Secure the Work Area: If you're working at a height, use a secure ladder and make sure the area below is clear of obstacles.

2. Gather Materials and Tools:

• Crack Filler: Choose an exterior-grade crack filler suitable for the material of your building (concrete, stucco, brick, etc.).
• Putty Knife or Trowel: Use a putty knife or a trowel for applying the filler.
• Wire Brush: Clean out the crack using a wire brush to remove loose debris and dirt.
• Caulk Gun (if using a tube-based filler): This is needed if your crack filler comes in a tube.

3. Prepare the Crack:

• Clean the Crack: Use the wire brush to clean the crack of any loose material, dirt, or vegetation.
• Remove Loose Debris: Ensure that the crack is free of loose debris by blowing it out or using a vacuum.

4. Application of Crack Filler:

• Cut the Nozzle: If you're using a tube-based filler, cut the nozzle at a 45-degree angle to the desired width.
• Apply Filler: Squeeze or trowel the crack filler into the crack, ensuring it's slightly overfilled.
• Smooth the Surface: Use the putty knife or trowel to smooth the surface of the filler and create a seamless finish.

5. Allow for Drying:

• Follow Manufacturer's Instructions: Allow the crack filler to dry according to the manufacturer's instructions. Drying times can vary based on the product and environmental conditions.
• Avoid Disturbance: Do not disturb or touch the filled crack until it's fully cured.

6. Sand or Paint (if necessary):

• Sand (if applicable): Once the filler is completely dry, you may need to sand the surface to achieve a smooth finish.
• Paint (if applicable): If the crack filler is visible and you want to match the surface color, paint over the filled area with an exterior-grade paint.

7. Regular Inspection:

• Monitor for Further Cracks: Periodically inspect the exterior of the building for new cracks. Address them promptly to prevent further issues.

8. Professional Help:

• Complex Cracks: If you're dealing with extensive or structural cracks, it's advisable to consult with a structural engineer or a professional contractor for a thorough assessment and appropriate solutions.

Tips:

• Weather Conditions: Choose a day with mild weather for crack filling. Extreme temperatures or rain shortly after application can affect the curing process.
• Quality Products: Invest in high-quality crack filler for better durability and longevity.
• Address Underlying Issues: If the cracks are a result of underlying structural issues, it's crucial to address those problems for a lasting solution.

Always follow the specific instructions provided by the crack filler manufacturer for the best results. If in doubt or dealing with significant structural issues, seek professional advice.