The Best Adhesives for Block Construction

The best adhesives for block construction are polyurethane-based adhesives, cement-based adhesives, epoxy adhesives, and construction adhesives. Each type offers unique benefits, from high-strength bonding to fast application. Choosing the right option depends on factors like load-bearing requirements, weather exposure, and material compatibility.

Our blog breaks down adhesive types, compares bricklaying solutions, and weighs up traditional mortar against modern alternatives.

Polyurethane-based adhesives provide strong, flexible bonds for block construction. These high-performance products resist moisture, making them ideal for outdoor and damp environments. Application is straightforward, requiring only a standard adhesive gun. Unlike traditional mortar, they cure quickly, reducing downtime on site.

Their flexibility allows for minor movement without cracking, which is beneficial in areas prone to ground shifts. Suitable for concrete, masonry, and lightweight blocks, they perform well under various conditions. While highly durable, they can be costlier than other options. Proper surface preparation ensures the best adhesion, preventing long-term failures.

Cement-based adhesives offer a solid bond for block construction. These mixes, often modified with polymers, improve adhesion and flexibility. Builders use them for laying concrete blocks, aerated autoclaved concrete (AAC), and masonry walls. Drying time varies, but they provide a strong, durable connection once set.

Applied with a notched trowel, they create a uniform surface that enhances stability. Weather resistance makes them ideal for external walls. While effective, they require precise mixing and correct water ratios to avoid weak spots. Used correctly, they offer long-lasting performance in demanding conditions.

Epoxy adhesives deliver exceptional strength in block construction. These high-bond solutions suit structural applications and repair work, including fixing a damaged block wall. They bond to concrete, masonry, and stone with superior resistance to chemicals and heavy loads.

Application involves mixing resin and hardener before spreading onto surfaces. Once cured, they create a rigid hold that withstands high stress. Because they set slower than other adhesives, working time must be planned carefully.

Though expensive, their durability justifies the cost in critical areas. For permanent fixes, they remain one of the strongest choices available.

Construction adhesives offer versatile bonding for blockwork. These solvent or polymer-based products stick to a range of materials, from concrete to lightweight blocks. Quick application speeds up projects, reducing reliance on traditional mortar.

Used for non-load-bearing walls and general repairs, they provide a secure hold without excessive curing times. Many options remain flexible after setting, preventing cracks from minor movement.

Proper surface preparation ensures optimal grip, avoiding adhesion failures. While not suited for structural walls, they work well for small-scale construction and patch jobs. Their convenience makes them a popular choice in modern building methods.

Traditional mortar has long been the go-to for block construction. Made from cement, sand, and water, it creates a strong bond when applied between blocks. Its workability allows for adjustments during laying, but curing takes time, and excess moisture can weaken the mix. Thick joints add to material costs and labour, making it less efficient for large-scale projects.

Modern block adhesives offer a faster, cleaner alternative. These products require less preparation and set quickly, reducing delays on site. Polyurethane and cement-based options create strong bonds with thinner joints, improving efficiency and minimising waste. Many adhesives also flex with movement, reducing the risk of cracking.