Stone adhesive suitable for exterior walls
Selection and Using Stone Adhesives on Outside Walls: Final In-depth Guide
Today, stone cladding on outdoor walls has become a widespread building aesthetic solution used in residential houses, offices, and industrial buildings. Besides being a solid method of construction, stone cladding creates the remarkable looks of buildings and their different perspectives. Still, the most important thing is that natural stone and its artificial analogs that are used as outside facades make their service longer with the help of high-quality stone adhesives appropriate for outdoor use. Unlike indoor adhesives or cement mortar, stone adhesives for external walls are made of materials which can withstand severe weather conditions. Normal adhesives cannot fulfill this task. The following paragraphs give a full overview of the essential features, types, and selection of outdoor stone adhesives for walls.
Cold and heat, rain erosion, sun rays, and moving structures create very challenging conditions for exterior stones. Still, some adhesives are able to withstand these natural phenomena and remain effective.
1. Outstanding Resistance to UV Radiation and Weather
The adhesive material used for stone cladding must be able to resist UV rays, high temperatures, and freeze-thaw cycles without yellowing or pulverizing. High-quality modified adhesive formulations are stable in the temperature limits from -20°C to 60°C.
2. Good Bond Strength and Anti-slip Properties
The exterior stone must be stuck well to prevent any sagging process when the glue is being cured.The final tensile and shear bond strength is much greater than that of standard mortar, eliminating the risks associated with falling stone panels on high-rise buildings.
3. Flexibility and crack-bridging properties
Building surfaces and stone products expand/compress under temperature fluctuations and building load. Normal bonding materials become cracked quickly and can lose their adhesive properties. Modified elastomeric stone adhesive offers great flexibility, helping to bridge tiny cracks in the substrate and to absorb any thermal movement occurring between walls and stone cladding that guarantees the stability of the entire facade.
4. Water- and vapor-proof features
Exterior walls are constantly subjected to rain and humid air. Correctly chosen stone adhesive creates a waterproof binding layer preventing the penetration of water through the fissures of stone and building surfaces. That helps to avoid internal wall dampness, mould, and efflorescence on the surface of stone helping to keep the facade clean.
Modern construction projects pay attention to eco-friendly materials. Currently existing quality external wall adhesive are based on non-toxic low VOC technology, which confirms the conformity to international standards. It does not emit harmful substances during its usage.
5. Types of wall stone adhesive
3 types of stone adhesive can be used for exterior walls. Each of them has its own positive sides and usefulThis product is widely used in the installation of various natural rocks, decorative stones, and stones of a smaller size on concrete surfaces, plastered concrete, and bricks. It gives the ability to use this adhesive in almost any project, making it suitable for both thin-layer and thick-layer work (up to 15 mm) and allowing for easy and an on-site application of the product without the need for any special equipment. The benefits of using this adhesive are as follows: strong adhesion to the substrate, excellent frost resistance, and low price, which makes it suitable for housing construction, villas, and ordinary commercial works as well.
2. Two Component Epoxy Stone Adhesive
This two-component adhesive is made from resin and hardener and is known for its extreme degree of bonding strength and durability. After curing epoxy stone adhesive shows amazing capability of offering water resistance, resistance to corrosion effect, as well as having no shrinkage at all. It is produced for usage in heavy stones, construction of the walls of skyscrapers, and for construction works in areas where saltiness has a high effect. The adhesive works perfectly for vertical constructions without even sagging under higher temperatures of about 30C and it offers high efficiency in use, since it can stick stones very fast (within 45 minutes after application).
3. Flexible Polyurethane Stone Adhesive
This polyurethane adhesive for natural stones has an excellent elastic nature compared to cement-based adhesives. It can be used for installation of stone materials of any shape on buildings with big deformations or with curved surfaces, providing stable conditions during installation of the stones.With excellent low-temperature resistance, it can remain flexible and stable in cold northern regions without causing any cracking failures during the winter freeze-thaw cycles.
Principal Criteria for Choosing the Exterior Wall Stone Adhesive
Choosing an appropriate adhesive is very important for the exterior wall quality of the construction. Choosing the cheapest products without any calculations can result in problems and hazards in the future. Follow these simple criteria of choosing:
1. Compatibility of the adhesive type with stone type
In particular, porous stones such as limestone and sandstone need to be glued with an alkali low-content polymer-modified adhesive as the latter will protect the stones from alkali penetration and discoloration. On the contrary, if the stones are dense and heavy such as granite or some kinds of marble used in the slabs then solid epoxy glue should ensure appropriate bearing capacity. Lightweight veneers need flexible polyurethane glue as the best solution since such veneer is usually installed on curved walls.
2. Correspondence to Region Climate
Regions where freezing temperatures last for long periods prefer adhesives with good freeze-thaw resistance and flexibility at low temperatures. In places near the coast salt damages the adhesive, thus the hardest chemical resistance is to be chosen. In region with high temperatures and intense UV radiation the adhesive should have anti-aging, anti-yellowing formula.
3. Similarity of Building Height and Project Level
Low-rise residential buildings using regular types of stones can suffice with cheaper cement adhesive. When working with skyscrapers it is also advisable to use solid structural epoxy glue for long-lasting bonding.The standard process for bonding stone for exterior walls includes the following four essential steps:
1. Proper preparation of the substrate surface
For proper bonding of stone to the exterior substrate, the surface should be flat, stable, clean, dry, and free from dust and floating debris. The substrate should be repaired and leveled (if necessary), to enhance the bonding of the adhesive. For porous substrates, priming could help reinforce the adhesion by preventing moisture from penetrating and interfering with the curing process.
2. Adhering to the rules of adhesive mixing and application
In case of cement-based adhesive, mixing should follow proper instructions regarding the ratio of water and powder. The mix should rest for 3 to 5 minutes before secondary mixing to activate polymers. In the situation of two-component epoxy adhesives, both the resin and the curing agent should be mixed in exact proportions in order to achieve complete curing. Adhesive should be spread onto the wall substrate and stone with the same thickness to avoid hollowing.
3. Ensuring proper installation and curing conditions for the adhesive.
The installation should not be conducted in severe weather conditions, such as heavy rains, wind, and temperatures below 5 °C or above 35 °C. Considering thermal movements of the exterior stone, the gap between the stone slabs should be compliant with building codes. During the curing period, the working surface should remain dry and free from vibration or pressure applied to the stone.
Common mistakes that should be avoided when applying the stone adhesive on exterior walls include:
– Replacing a specialized adhesive by cement mortar. A simpler mortar can be less flexible, less weatherproof, and less effective in terms of bonding strength.
– Trying to minimize expenditure. Inferior adhesives are not adapted to resist harmful UV rays and will develop the aging process pretty fast resulting in numerous repairs and dangers arising from unsafe conditions.
– Not preparing the substrate properly. Dust and oil residue, as well as loose layers affect the bonding of the adhesive.
– Making mistakes in mixing the ingredients together.
In conclusion, the proper adhesive for stone external cladding is a foundation of success in the execution of the façade building project.
