Sealant and mastic help develop barriers against environmental factors. These specialised materials serve important purposes like maintaining building integrity and providing protection in wet areas and fire-rated installations.
From movement accommodation in joints to fire protection around service penetrations, choosing the best product impacts long-term durability.
How Do I Determine the Best Depth-to-Width Ratio When Applying Silicone Sealant to Expansion Joints?
When applying the best silicone sealant to expansion joints, maintain a depth-to-width ratio of 1:2 for joints up to 25mm wide. For wider joints, a ratio of 1:1 is suitable. The minimum depth should never be less than 6mm for proper adhesion.
Here are some key factors to think about.
- Joint width must accommodate expected movement
- Use the closed-cell backing rod to control the depth
- Calculate maximum joint movement at extreme temperatures
- Allow for proper tooling depth at edges
Intumescent Mastic vs Builders Mastic: What Are the Differences for Sealing Around Fire Barriers?
Intumescent mastic expands when exposed to heat, creating a robust fire-resistant barrier that can provide up to 4 hours of protection. It's engineered for sealing service penetrations and maintaining the integrity of fire compartments.
When exposed to temperatures above 302°F (150°C), it expands up to 7 times its original volume. Regular builders' mastic offers basic gap-filling properties but lacks the expanding characteristics needed for fire protection.
Always choose intumescent products tested to relevant fire safety standards and rated for the specific application. Also, intumescent mastic requires specific application techniques and proper depth to ensure effective fire protection.
What Properties Should I Consider When Buying Sealants for Bathrooms?
A waterproof sealant for shower and bathroom spaces must resist constant moisture exposure and prevent mould growth. Consider these properties before making a decision.
- Mould and mildew resistance rating
- Movement capability of 25% (expand and compress by 25%)
- Chemical resistance to cleaning products
- UV stability for natural light exposure
- Fast cure time to limit disruption
- Clear or colour-matching options
Should I Use a Gunnable Mastic or a Trowelling Mastic for Large Surface Areas?
Trowelling mastic is generally more suitable for large surface areas, offering better control over thickness and coverage. It offers improved gap-filling and works effectively across wider areas, particularly with floor sealant or sealant for cement floors. The consistency allows for smoother application and better levelling.
When working with large areas, trowelling mastic provides reduced waste compared to gunnable options. However, ensure proper substrate preparation and use recommended trowel sizes for best coverage and performance.
4 Key Considerations When Choosing Window Mastic for Buildings With Thermal Expansion
Selecting the right window mastic is crucial for maintaining building envelope integrity. Think about these 4 essential points.
- Movement capability: Buy products rated for +50% movement to accommodate thermal cycling. This ensures the mastic can expand and contract with temperature changes without losing adhesion or creating gaps
- UV stability: Choose products with proven resistance to sunlight degradation. Look for mastics specifically formulated with UV inhibitors to prevent yellowing, cracking or breakdown from sun exposure
- Substrate compatibility: Ensure proper adhesion to both frame and building materials. Test compatibility with aluminium, PVC, wood, concrete and other building materials before full application
- Service life: Use window mastic with 20+ year performance ratings for long-term durability