How should a surface be prepared before applying the silicone repellent?

The surface must be clean, free from dust, dirt, oil, and efflorescence, and thoroughly dry. Cracks up to 0.5 mm should be filled and allowed to cure (Clause 4).

What is the recommended method of application?

Apply by brush or a low-pressure spray, starting from the top and working downwards. Apply a flood coat to saturate the surface without excessive runoff (Clause 5).

How can one test the effectiveness of the treatment?

After a minimum drying period of 72 hours, conduct a water absorption test. The water absorption of the treated surface should not be more than 10 percent of that of an untreated surface (Clause 7.2).

Can this be applied on painted surfaces?

No, the code specifies application on unpainted surfaces. Existing paint must be completely removed as it will prevent the repellent from penetrating the substrate.

IS 12054

: 1987

Code of practice for the application of silicone-based water repellents

CurrentSpecializedCode of PracticeMaterials Science · Waterproofing and Damp-Proofing

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This standard outlines the code of practice for applying silicone-based water repellent solutions to above-ground masonry and concrete surfaces. It specifies the material requirements, surface preparation procedures, application methods, and tests to verify the effectiveness of the treatment.

Code of practice for the application of silicone-based water repellents

Quick Reference Values

Minimum solid silicone content in concentrate20 percent by mass

Typical dilution ratio (concentrate:solvent)1:10 to 1:12 by volume

Typical coverage rate (diluted)3 to 7 m²/litre

Minimum drying period before testing72 hours

Post-treatment water absorption limit<10% of untreated surface absorption

Maximum size of cracks to be pre-filled0.5 mm

Practical Notes

This treatment is a water repellent, not a waterproofing membrane; it will not seal visible cracks or resist hydrostatic pressure.

The surface must be thoroughly dry and clean before application to ensure proper penetration and effectiveness. Application on a damp surface will be ineffective.

The treatment's effectiveness degrades over time due to UV exposure and abrasion; periodic reapplication every 3-5 years may be necessary.