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NBS Source

Sikasil® WS-355

Verified by manufacturer 2 months ago

Sika Limited Third party certifications:
  • BSI Kitemark

    BSI Kitemark

    Certificate type

High performance, neutral-curing, low modulus silicone weather sealant.

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+44 (0)1707 394444


For professional use only. To be gunned into place. Suitable for jointing natural stone applications such as:

  • Marble.
  • Granite.
  • Sandstone.
  • Quartzite.
  • Facades (e.g. cladding of natural stone or other materials).

Available in 300 ml or 600 ml. Consult manufacturer for information regarding suitable preparation and application methods for this product. Sika recommend project specific stain testing to confirm the performance of the product.


High performance, neutral-curing, low modulus silicone weather sealant with a high movement capability and good adhesion to porous and non-porous substrates. Developed for use in natural stone applications.

Features and benefits:

  • Does not stain areas adjacent to the joint or the joint edges, unlike with conventional silicone sealants.
  • Non-streaking.
  • Movement capability of ±35%.
  • Solvent free, with very low emissions.
  • UV and weather resistant.
  • Adheres to a wide range of materials, including natural stone, concrete, glass, metals, coated and painted metals.

General information




Pr_30_31_76_77 Silicone construction joint sealantsPrimary


F30/610 Movement joints with sealant

F30/76 Movement joints with sealant

H11/772 Curtain walling joint assembly sealants

H11/777 Weathersealing for structural sealant/ bonded glazing

H30/160 Profiled plastic sheet rooflights or wall lights

H31/110 Metal

H31/120 Metal

H42/661 Sealant joints

H51/610 Sealant joints

H51/630 Movement joints

H71/770 Wedge fixing into joints/ Chases

H71/780 Wedge fixing into damp-proof course joints

H71/790 Screw fixing into joints/ Chases

H72/770 Wedge fixing into joints/ chases

H72/780 Wedge fixing into damp-proof course joints

H72/790 Screw fixing into joints/ chases

H73/770 Wedge fixing into joints/ chases

H73/780 Wedge fixing into damp proof course joints

H73/790 Screw fixing into joints/ chases

H74/770 Wedge fixing into joints/ chases

H74/780 Wedge fixing into damp proof course joints

H74/790 Screw-fixing into joints/ chases

H75/770 Wedge fixing into joints/ chases

H75/780 Wedge fixing into damp proof course joints

H75/790 Screw-fixing into joints/ chases

H92/770 General sealants

L10/75 Sealant joints

L10/810 Sealant joints

L20/80 Sealant joints

L20/820 Sealant joints

M20/653 Sealant movement joints with stop bead edgings

M21/530 Sealant joints

M21/85 Sealant joints

M40/75 Sealant movement joints

M40/815 Sealant movement joints

P31/40 Sealing around services

P31/710 Sealing

Product range


Specification data - Silicone construction joint sealants




~1.49 kg/L.


Non-sag properties: <2 mm.

Service temperature

-40°C to +150°C.

Application temperature


Shore A hardness

(CQP 023-1 / ISO 868): ~22.


Movement capability (ASTM C 719): ±35%.

Elongation at break

(CQP 036-1 / ISO 37): ~800%.

Thermal resistance

180°C. Short term: 200°C (four hours), 220°C (one hour).


(CQP 036-1 / ISO 37): ~1 N/mm.

Third party certifications

  • British Standards Institution (BSI) - certficate : Meets the requirements of ISO 11600 25 LM F and G, ASTM C 920 (class 50), ASTM C 1248, TT-S00230C, and TT-S001543A
  • British Standards Institution (BSI) - certficate : CE marked according to EN 15651-1:2012, F EXT-INT 25HM, EN 15651-2:2012, G CC 25HM, and certified by Control Body 1119

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