General Construction 247 views Sep 02, 2016

Fire-rated sealants belong to a specialised market so people should never assume the product they select will necessarily provide the required protection. There is a range of available fire-rated sealants, each containing products designed for use in different building applications.

I’d advise anyone in the market for a fire-rated sealant to check its product sheet before buying. Just because someone says the product contains the necessary flame-resistant properties doesn’t guarantee its quality. To ensure you’re choosing the correct protective sealant for your application, for peace of mind, ask for the product’s test data sheet as proof of its properties. 


 Wrong specification – potentially poor outcome

The consequences of selecting the wrong product can be disastrous. Some years ago, a fire broke out on the eighth floor of a building packed with mineral wool between the concrete slab and the curtain walling. The wool had a lot of organic binders, so the fire spread up the side of the building, catching the binders alight on the upper floors as it went. Although the building was fire-rated, the flames spread from the 8th to the 13th floor because the quality of mineral wool on its own wasn’t suitable for the application. Mineral wool, which in itself provides a fire rating, can also deteriorate and fall out of a joint if a building is affected by water ingress.

There’s a general lack of knowledge about fire-rated sealant and its application. People simply pick a sealant off the shelf thinking, “Oh, that says it’s fire-rated, therefore it’s bound to work.”

Sikasil® FS-665 SL, a fire-rated, self-levelling, silicone sealant, is designed to protect buildings from fire-spread and smoke. It’s used between a building’s floor slab and façade and involves sealing joints ranging from 50mm to 200mm.

Sikasil® FS-665 SL, once poured into a building’s joints, has a number of benefits:


  • It provides a liquid-protective layer for mineral wool
  • Prevents the spread of smoke and fire between floors
  • Can accommodate movement of floor slab


Pre-buy peace of mind

Vertical building joints can be treated with straightforward sealants such as polyethylene backer rod. If a higher-performance product is required, Sika provides a ceramic cord which optimises the performance of the joint with its superb insulation and fire-resistant properties.

For those unsure of the correct fire-rated solution for a particular application, there is plenty of specialist advice available. Fire-resistant glazing is particularly problematic.  Too often, people assume a piece of toughened glass with a bit of sealant around equates to a fire-resistant window - it isn’t the case.  Fire-resistant glazing needs to have a tested and approved system.

Sika is a member of the Glass and Glazing Federation which has its own team of specialists - Fire Resistant Glazing Group,consisting of manufacturers, distributors and installers of fire resistant glazing products. Its goal is to work with the wider fire safety community in the UK, therefore it’s well worth visiting: for an informed opinion on such issues.

Before specifying a fire-rated sealant, it’s also worth seeking expert advice from a company such as Sika which provides a wide range of quality fire-rated sealants. 

Due diligence in terms of the seemingly minor aspects of a building’s design such as joint sealants could prevent some major problems in the future.

For more information please call 01707 394444, or visit

By Jeff Richards, Sika Product Manager