Sealants and mastics act as essential barriers against environmental elements. These materials play a critical role in preserving structural integrity, particularly in wet areas and fire-rated construction zones.
Whether accommodating movement in joints or sealing service penetrations for fire protection, selecting the right product directly influences long-term durability and performance.
What’s the Ideal Depth-to-Width Ratio for Silicone Sealant in Expansion Joints?
When applying silicone sealant to expansion joints, use a 1:2 depth-to-width ratio for joints up to 25mm wide. For joints wider than 25mm, a 1:1 ratio is more appropriate. Ensure a minimum sealant depth of 6mm for optimal bonding and flexibility.
Key considerations include:
- Ensuring joint width accommodates anticipated movement
- Using closed-cell backing rod to maintain consistent depth
- Factoring in expansion/contraction due to temperature changes
- Allowing proper tooling at the edges for smooth finishes
Intumescent vs Builder’s Mastic – Which One to Use Around Fire Barriers?
Intumescent mastic is designed to expand under extreme heat, sealing service gaps and providing up to 4 hours of fire resistance. It activates at around 150°C (302°F), expanding up to seven times its original size to create an airtight barrier.
By contrast, traditional builder’s mastic is a gap-filler without fire-rated properties. It doesn't expand under heat and isn't suitable for maintaining fire compartment integrity.
For fire-rated applications, always use tested and certified intumescent products, and apply them according to manufacturer specifications to achieve the required performance.
What Features Should I Look for in a Bathroom Sealant?
A high-quality bathroom sealant must withstand constant moisture and resist mould. Key properties include:
- Excellent mould and mildew resistance
- Minimum ±25% movement capability
- Strong resistance to cleaning agents and chemicals
- UV stability for long-term exposure to sunlight
- Fast curing to minimise disruption
- Colour-match or clear options for a clean finish
Should I Use Gunnable or Trowelling Mastic for Larger Areas?
For wide applications, trowelling mastic is the better choice. Its thicker consistency offers improved control, better coverage, and enhanced gap-filling capabilities, making it ideal for floors and other large surfaces.
Compared to gunnable mastic, trowel-applied options reduce waste and ensure a smoother, more even application. Just ensure the substrate is clean and use the correct trowel size for best results.
Top 4 Factors When Selecting Window Mastic for Buildings with Thermal Expansion
Choosing the right window mastic ensures durability and energy efficiency. Here are four key factors to consider:
- Movement Capability: Choose mastics rated for at least ±50% movement to handle expansion and contraction without cracking or pulling away.
- UV Stability: Look for mastics with UV inhibitors to prevent yellowing, cracking, or degradation under prolonged sun exposure.
- Substrate Compatibility: Test adhesion on all relevant materials—aluminium, PVC, wood, and concrete—before full application.
- Service Life: Opt for products with proven 20+ year durability ratings to ensure long-term performance and value.