10.0 fl.oz. (295 ml) cartridge
20 fl.oz. (600 ml) sausage

Sikasil ® WS-295
Neutral cure, weather sealing silicone sealant


Sikasil-WS 295 sealant is a one part, neutral cure for use in most common weatherproofing applications on a wide variety of materials. Meets the requirements of ASTM C-920, Type S, Grade NS, Class 50, Use NT, M, G, A, O; TT-S-00230C, Type II, Class A; CAN/CGSB-19.13-M87, AAMA 802.3 Type II, AAMA 803.3, AAMA 805.2, AAMA 808.3.

Where to Use

  • Sikasil WS-295 silicone sealant has been specifically designed:
    • As a weatherseal in both conventional glazing and structural glazing applications, including cap, toe and heel beads
    • As a weatherseal in glass to glass butt joint glazing
    • Sealing expansion and control joints in precast concrete panels and metal curtain walls.
    • Perimeter sealing of doors, windows and other building components
    • Adhering stiffeners to building panels
    • Excellent for use in unitized curtain wall systems


  • Versatile medium modulus
  • Unaffected by most atmospheric conditions
  • Non-staining
  • Joint movement +/-50%
  • Excellent adhesion
  • One-component
  • Excellent gunnability in all temperatures

How to Use

Surface Preperation

The substrate must be clean, dry, frost free, sound and free of any oils, greases or incompatible sealers, paints or coatings that may interfere with adhesion.
POROUS SUBSTRATES - clean by mechanical methods to expose a sound surface free of contamination and laitance.
NON-POROUS SUBSTRATES - for cleaning non-porous substrates, use two rag wipe method using xylene or an approved commercial solvent. Allow solvent to evaporate prior to sealant application.


Sikasil WS-295 is designed to obtain adhesion without the use of a primer; however, certain substrates may require a primer. Test by applying the sealant and/or primer sealant combination to confirm results and proposed application methods. Refer to Technical Data Sheet for primers Sikasil 2100 primer and contact Technical Service for additional information. 


The number of joints and the joint width should be designed for a maximum of +/-25% movement of joint width at time of installation. The depth of the sealant should be 1/2 the width of the joint. The maximum depth is 1/2 inch (13mm) and the minimum is 1/4 inch (6mm). To control joint depth, use closed cell polyeth- ylene, non-gassing polyolefin or open cell polyurethane backer rod. If joint depth does not allow for backer rod, use polyethylene bond breaker tape to prevent three-sided adhesion. Closed cell backer rod should be 25% larger than joint width; do not compress more than 40%. Open cell should be compressed 40%. Do not use open cell rod in horizontal on grade joints or with E.I.F.S. Ready to use, apply using professional caulk- ing gun. Do not open product container until preparation work has been completed. Apply sealant using consistent, positive pressure to force sealant into the joint. Tool sealant to create a concave joint shape and maximum adhesion. Dry tooling is recommended. DO NOT use soapy water or other liquids when tooling.


Use xylene, denatured alcohol or mineral spirits to remove uncured sealant from substrate and equipment. Follow solvent manufacturer's instructions for use and warnings. Cured material can only ne removed mechanically.


  • All structural silicone glazing applications must be reviewed and approved by Sika Facades, Fenestration and Insulating Glass Tech Service at 1-800-641-0234.
  • Do not allow sealant to come in contact with solvent during cure.
  • Do not allow sealant to come in contact with curing polyurethane sealants during cure.
  • Not intended for immersion.
  • Sealant may be applied below freezing temperatures if substrates are completely dry, frost free and clean. Contact Technical Service for more information.
  • Do not apply when substrate temperatures are below -20°F or above 130°F.
  • Not recommended for structural glazing applications
  • Not recommended for horizontal vehicular traffic.
  • Do not apply to surfaces that will be painted as sealant surface will not hold paint.
  • Do not apply to substrates that bleed oil, plasticizers or solvent.
  • Do not apply to damp or wet substrates.
  • Lower temperature and humidity will extend tack free and cure rates.
  • Allow treated wood to age six months before application.
  • Brass and copper may be discolored. Test apply prior to application.
  • Test sensitive substrates, such as mirror backings, for compatibility before use.