Bostik S551 – neutral silicone for gutters and roofs

Keo Bostik S551 ROOF ‘N’ SEAL GUTTER SILICONE is a one-component, low modulus neutral curing silicone, providing excellent adhesion to various common surfaces, especially all types of roofing and guttering. Advantages:

  • Strong adhesion to all types of roofs, gutters, and other building substrates.
  • Color stability and UV resistance, unaffected by ultraviolet rays and weather.
  • Permanent elasticity.
  • Neutral maintenance, non-corrosive to metal surfaces.


Bostik S551 ROOF ‘N’ SEAL GUTTER SILICONE is specially developed for metal roofing systems, water downpipes, metal water tanks, drains, skylights, metal and PVC pipes and fittings, irrigation pipes, or air conditioning systems. S551 is commonly used as a versatile sealant for construction materials.

Instructions for use

A precise-sized joint can absorb movements between construction materials. The depth of the joint must always be proportional to its width. The general principle is that the ratio between the depth and width of the joint is 1:1 when the joint width is up to 10 mm, with a minimum width and depth of 5 mm. For joints wider than 10 mm, the depth is the width divided by 3 plus 6 mm.


  • Not suitable for fish tanks and drought pools.
  • Discoloration may occur in dimly lit areas and due to chemical exposure.
  • Not suitable for PE, PP, PC, PMMA, PTFE, plastic, neoprene, and bitumen substrates.

Surface preparation & finishing

Application temperature + 5°C to + 40°C (applicable to both environment and surface). All substrates must be solid, clean, dry, free from grease, and dust. Bostik S551 ROOF ‘N’ SEAL GUTTER SILICONE adheres perfectly without the need for primer on most non-porous surfaces. Porous surfaces are treated with primer. Always ensure to check the adhesion before application.


Bostik S551 ROOF ‘N’ SEAL GUTTER SILICONE cannot be painted. We recommend using adhesive tape to cover the edges of the joint to prevent surfaces requiring paint from being contaminated with silicone.


Cleaning tools after use with water is recommended. Hands can be cleaned with a towel and/or water and soap. Hardened substances can only be removed mechanically.


In the original packaging, unopened, stored within a temperature range of + 5 ° C to + 25 ° C, the shelf life is up to 12 months from the date of manufacture, stored in a dry place.


100% modulus DIN 53504 S2 0,60 N/mm2
Application temperature +5°C – +40°C
Base Neutral silicone
Curing time @ +23°C/50% RH 2.5 mm/24h
Density ISO 1183-1 1,5 g/ml
Joint movement ASTM C 719 ±25%
Shore A hardness ASTM C661 30
Kéo dài khi nghỉ ASTM D412 580%
Tack free time 15 mins @ +23°C/50% RH
Temperature resistance -30°C – +120°C
Tensile strength ASTM D412 1,70 N/mm2
These values are typical properties and may vary by +/- 3%
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