A deep understanding of the advantages and limitations of various types of silicone waterproofing agents is the key to making a reasonable choice. Waterproofing agents with different chemical compositions and forms have significant differences in performance, construction adaptability, durability and economy, which directly affect the quality and cost-effectiveness of the final waterproofing project. The following will systematically compare the four main types of silicone waterproofing agents from the three dimensions of technical performance, construction characteristics and economy.


The most prominent advantage of methylsiliconate waterproofing agents lies in their economy and construction convenience. As the lowest-priced type of silicone waterproofing agent on the market, its material cost is only 1/5 to 1/3 of that of silane products, which is particularly suitable for large-scale projects with limited budgets. In terms of construction, methylsiliconate has low requirements for base surface preparation and can even be directly constructed on wet substrates without affecting the bonding performance of the waterproof layer and the substrate. This type of product is usually a single component, ready to use, without complex preparation, and can be constructed using an ordinary sprayer or roller brush, which greatly improves construction efficiency. From the technical performance point of view, methylsiliconate has no corrosion effect on steel bars, has micro-expansion characteristics that can compensate for the shrinkage of mortar and concrete, and has good weather resistance and significant waterproof effect in the short term. However, the disadvantages of this type of product are also obvious: strong alkalinity (pH can reach 13-14) not only has the risk of corrosion to the skin of construction workers, but also may damage certain sensitive substrates; white sodium salt/potassium salt generated by reaction with carbon dioxide in the air will precipitate on the surface, affecting the appearance; more seriously, in a continuous alkaline or frequent dry-wet cycle environment, the waterproof component will gradually lose, resulting in the waterproof function usually failing within 1-3 years. Therefore, this type of product is suitable for short-term waterproofing requirements or protection of non-exposed parts.


Silicone resin waterproofing agents perform well in weather resistance and temperature resistance. The waterproof film formed by this type of product can withstand temperature changes from -60℃ to 250℃, and is suitable for use in extreme climate areas. Silicone resin also has excellent UV resistance and aging resistance, can maintain elasticity for a long time, and adapt to the thermal expansion and contraction of the substrate. Compared with methylsiliconate, silicone resin waterproofing agents are usually neutral or weakly acidic, more friendly to construction workers and substrates, and will not cause whitening or yellowing problems. However, silicone resin waterproofing layers have problems such as high gloss, sticky surface, and poor mechanical scrubbing resistance, which limit their application in places where the original appearance of the building needs to be maintained17. More importantly, the effective life of ordinary silicone resin waterproofing layers is usually only a few months to 2 years, after which they will fail due to resin degradation, and must be chemically modified (such as increasing the methyl content) to extend the service life. The price of silicone resin products is moderate, between methylsiliconate and silane, suitable for projects with medium budgets and special requirements for weather resistance.


Silane waterproofing agents represent the highest level of current silicone waterproofing technology, and their comprehensive performance is the best. The small molecule characteristics of this type of product give it an amazing penetration depth, which can reach 6-12mm at 100% concentration, far exceeding other types of waterproofing agents. The chemical reaction between silane and the substrate forms a waterproof layer bonded by chemical bonds, which will not fail due to physical wear and tear, and exhibits excellent durability. Application cases in European and American countries have confirmed that its effect can be maintained for 10-20 years. At the same time, the surface treated with silane waterproofing agent maintains a natural appearance, without gloss changes, and has excellent anti-fouling, anti-freeze and thaw and chemical corrosion resistance. From an environmental protection perspective, high-quality silane products are non-toxic and odorless, with extremely low VOC content, and are almost harmless to construction workers and the environment. However, this type of product also has obvious shortcomings: high technical requirements, limited domestic production capacity, and mainly dependent on imports, resulting in high prices, which are 3-5 times that of methylsiliconol salts; in addition, it has high requirements for the cleanliness of the substrate surface, which must be free of oil and water, and requires a certain ambient temperature (above 5°C) to fully react. Silane products are particularly suitable for long-term waterproofing projects in important buildings, cultural relics protection and harsh environments.


Silicone emulsion waterproofing agents have obvious advantages in environmental protection and ease of use. The characteristic of using water as a dispersion medium makes its VOC emission extremely low, and no toxic solvents evaporate during the construction process, which is suitable for use in confined spaces and places with high environmental protection requirements. Compared with solvent-based products, emulsions have stronger penetration into porous materials such as masonry and concrete, and the cost is relatively low. Emulsion-type products are diverse in form, including both dilute emulsions that can be directly sprayed and cream-like products suitable for brushing. The latter is particularly convenient for vertical and top surface construction and can reduce material loss. However, the stability of silicone emulsions is the biggest challenge. Demulsification, stratification or deterioration are prone to occur during storage and transportation, affecting the use effect; in addition, its waterproof durability is generally between methylsiliconol salts and silanes, usually 5-10 years. The price of emulsion-type products is moderate, slightly higher than silicone resins but lower than silanes, and is an economical choice for projects such as home decoration and old house renovation.


Compared with construction characteristics, methyl silicon alkoxide and silicone emulsion are the simplest. They can usually be sprayed or rolled after being diluted with water at a ratio of 1:10-1:15. The construction area per person per day can reach 300-500 square meters. Silicone resin and silane products require special equipment, such as low-pressure sprayers or airless sprayers, and have stricter requirements for base treatment. All types of silicone waterproofing agents need to be cured for 24-72 hours after construction to fully cure, and should be avoided from rain or mechanical damage during this period8.


Table: Recommended scenarios for four types of silicone waterproofing agents


Methylsiliconol salts Short-term waterproofing projects, projects with limited budgets, hidden areas High-end decorative surfaces, long-term exposed areas, acidic environments Low initial cost, but frequent maintenance required
Silicone resin Extreme temperature environments, areas requiring elastic waterproofing layers Cultural relics that need to maintain their original appearance, high wear areas Medium investment, medium life
Silanes Important buildings, cultural relics protection, harsh environments, long-term waterproofing Ultra-low budget projects, temporary buildings High initial investment, good long-term economic efficiency
Silicone emulsions Home decoration, places with high environmental protection requirements, renovation of old houses Long-term flooding areas, high-temperature base surfaces Balanced selection
In actual projects, no waterproofing agent is omnipotent, and trade-offs must be made according to specific needs. For large projects, you can consider using different types of waterproofing agents in different parts, or choose compound products to obtain more comprehensive performance. With technological advances, domestic companies are committed to developing new waterproofing agents with performance close to imported silane products but better prices, which will provide the market with more cost-effective options.



Scientific selection method for silicone waterproofing agents
Selecting the right silicone waterproofing agent is a decision-making process that requires comprehensive consideration of multiple factors, including substrate characteristics, environmental conditions, performance requirements, construction restrictions, and budget constraints. Scientific selection can not only ensure waterproofing effects, but also optimize resource utilization and extend the service life of buildings. Based on the characteristics of existing products in the market and engineering practice experience, we can establish a systematic selection framework from the following key dimensions.


Substrate type and surface state are the primary considerations for selecting waterproofing agents. The compatibility and reactivity of different building materials to waterproofing agents vary significantly. For strong alkaline substrates such as concrete and cement mortar, methylsiliconate and silane products perform well because they can tolerate high alkaline environments and combine well with cement hydration products. For natural stones such as marble and granite, neutral or weakly acidic silane or silicone resin products should be preferred to avoid discoloration or surface corrosion of stones that may be caused by alkaline waterproofing agents. For neutral substrates such as bricks, sandstone, and ceramics, silane/siloxane hybrid products such as Z-6689 developed by Dow Corning are particularly suitable because they can quickly form a hydrophobic effect on neutral surfaces. The surface condition of the substrate is also important: glossy materials require low-gloss, scrub-resistant waterproofing agents such as silanes; while rough or matte surfaces can choose film-forming products such as silicone resins. Especially porous or loose substrates (such as sandstone and gypsum) require products with a large penetration depth and moderate solid content to avoid surface conjunctivaeion that hinders the evaporation of internal moisture.


Environmental conditions and service life requirements directly affect the choice of waterproofing agent types. For outdoor exposed areas (such as exterior walls, roofs, bridges), silane or silicone resin products that are resistant to UV rays and high and low temperature cycles should be selected. Their weather resistance is far better than methyl silicon salts. Humid environments or areas that are immersed in water for a long time (such as swimming pools and basements) require chemically bonded waterproofing agents such as silanes, rather than physically adsorbed methyl silicon salts. In chemically corrosive environments (such as chemical plants and sewage treatment facilities), high methyl content