Water Repellent, Breathable Protective Coating for Concrete


Si-Rex03 Silicone Resin Emulsion Paint (SREP) is a state-of-the-art commercial exterior wall and façade paint system purpose developed as a coating for concrete and masonry substrates.

The advanced silicone resin binder system delivers a sophisticated architectural matte finish with proven protection and performance benefits including strong adhesion.

A water-based, one-part system, Si-Rex03 is easy to apply by spray, roller or brush (with convenience of a long pot life) for a great look and finish.


Si-Rex03 protects the substrate with active water repellency. It also lets the substrate breathe by allowing entrapped moisture to outgas thus enhancing structural integrity through to limiting any peeling or flaking. This breathability delivers proven protection in environments from freeze-thaw to high heat/humidity.


The silicone in Si-Rex03 reacts to form a 3-dimensional “quartz-like structure” of alternating silicone and oxygen atoms; a durable structure unaffected by UV light and weathering conditions. Water repellent groups line the pores of the paint that stop the ingress of liquid water but allow vapor to outgas. This unique structure is the key to the performance of Si-Rex03 and its ability to protect the concrete or masonry substrate for decades.


Si-Rex03 is available in many colors including a wide range of neutral and earthy tones that complement concrete and masonry substrates. Only high-grade, inorganic oxide pigments, resilient to UV light exposure and severe weathering, are used for optimal fade resistance and long-lasting dynamic colors.

Refer Product Data Sheet (TDS) for use and application guidelines.


Environmental consideration with colorants being VOC (Volatile Organic Compounds) and APE (Alkyl Phenol Ethoxylate) free thus compliant with latest requirements and anticipated regulations.


Si-Rex03 system is approved and/or specified as a preferred protective coating for concrete by numerous state transportation and other state/county/city authorities plus chartered organizations for use on concrete infrastructure and facilities.

Prestressed Beam crop

Si-Rex03 was evaluated, and is approved for use, in limiting the deleterious effects caused by expansion in concrete structures due to ASR (alkali-silica reaction) and/or DEF (delayed ettringite formation) activity.

Si-Rex03 can reduce level of moisture (relative humidity) within the substrate, thus improving structural integrity of the concrete and so extend service life of structures.



Designed specifically for use with Si-Rex03, the use of penetrating primer Si-Prime on bare substrates adds to the performance, durability and substrate protection traits of the Silicone Resin Emulsion Paint (SREP) coating system.

For use on cast-in-place concrete, precast concrete. stucco, blockwork (CMU), brickwork, stone and other substrates.


Klaas Coatings (North America) LLC
PO Box 25122
Dallas, TX 75225-1122

T: 866-317-3633 (toll free)
F: 214-363-8422

E: info@klaascoatings-northamerica.com

Markets We Supply

Transportation Infrastructure
Parking Structures
Office Buildings
Commercial and Retail
Warehousing and Distribution
Precast Concrete Fabricators
Historic Structures
Sport Complexes
Condominiums and Multi-Family
Tourism Infrastructure
Schools and Colleges

Technical Support

Looking for Application Guidelines?
Needing specification reference?



All orders supplied ex-factory – products not available through retailers.

Some regional building product distributors may carry, or order in, product as needed.

Product packaging
(packed volume by weight):

Si-Rex03 - 5 Gallon Pail or 55 Gallon Drum
Si-Prime - 5 Gallon Pail

Si-Rex03 orders are custom batch tinted at factory. Batch tinting ensures exact same color pail-to-pail. Minimum Order Quantities (MOQ) apply; contact for details.