🧰 Practical guide to choosing sealants for exterior surfaces and structures

In construction, renovation and technical work, choosing the right sealant can make the difference between a long-lasting job and one prone to premature deterioration. There are different types of sealing products, each with specific characteristics, performance and intended uses.

Here is an overview to help designers, technicians and professionals make an informed choice.

🏗️ 1. Structural fixings with two-component epoxy resins

Two-component epoxy resins (consisting of resin and hardener) guarantee:

• High adhesion to cementitious and stone surfaces
• Outstanding mechanical and chemical resistance
• Excellent performance even in critical conditions

Ideal use: ancoraggio of concrete slabs, steps, precast elements and structures subjected to permanent loads.

🌬️ 2. Elastic sealing with silicones and polyurethanes

When surfaces are subject to thermal micro-movements or vibrations, it is preferable to use elastomeric sealants:

• Polyurethane products are extremely weather-resistant and paintable
• Silicones offer elasticity and resistance to temperature changes

Ideal use: giunti between exterior flooring, window and door frames, façades, elements exposed to rain and sun.

🎯 3. Simplified applications with acrylic sealants

Acrylics are water-based sealants, ideal for lighter jobs:

• Quick and easy application
• Can be painted afterwards
• Good coverage on interior and exterior surfaces

Ideal use: masonry maintenance, internal cracks, surface cracks.

💧 4. Humid environments: the role of butyl sealants

In the presence of persistent humidity, products with strong water retention are needed:

• Butyl sealants also adhere to damp surfaces
• Guarantee long-lasting waterproofing
• Excellent resistance to aging

Ideal use: foundations, roofs, underground surfaces or surfaces exposed to the elements.

🛡️ 5. Invisible protection: silane and siloxane impregnating agents

Rather than sealing, these products penetrate the material, creating a barrier against water and dirt:

• They do not alter the aesthetic appearance of the surface
• They provide deep protection
• They reduce the formation of mold and limescale

Ideal use: natural stone, historic facades, porous outdoor pavements.

🧪 How to choose the right sealant?

To find the right product, consider these essential elements:

• Surface type: every material has different needs — concrete, stone, metal, wood…
• Environmental conditions: check whether the area is prone to humidity, large temperature fluctuations, or direct exposure to rain and sun.
• Expected structural movements: if the area is subject to expansions, vibrations or stresses, an elastic sealant is required.
• Desired aesthetic appearance": choose from paintable, invisible, or decorative-finish products, depending on the final result you want to achieve."
• Durability and mechanical stress`: consider how much stress the surface will be subjected to — permanent fixings require high-performance resins.`

✅ A good choice is always guided by observing the context and the technical characteristics. That way every intervention will be effective, long-lasting and in line with real needs.

Have you ever used a product unsuitable for the context? Tell us about your experience!