Joints & gaps

Fire Retardant Sealants & Organic Sealants

Buildings move. They expand in summer, settle over years, and shake a little every time a lift runs. A seal that cannot move with them cracks — and a cracked seal is an open gap.

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Sealed service penetration in a fire-rated wall — **Joints that still move**Flexible where the building flexes, so the seal does not crack in its first summer.

UL Listed

Armacell fire stop systems

CBRI

CBRI Certified

Ameetuff mortar & coatings

NBC
IV

NBC Part-IV

Documented to the standard

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Before, during and after

In one paragraph

What it actually is.

Fire retardant sealant is a flexible material used to close linear joints, construction gaps and small service penetrations in fire-rated walls and floors. Unlike mortar, it stretches and compresses with building movement while keeping its fire rating. We use CBRI tested Ameetuff fire retardant and organic sealants, applied to the depth and width the tested system requires.

The joints are the part of the passive fire package that people assume will look after itself. A wall meets a floor slab and there is a gap; two panels meet and there is a gap; an expansion joint runs the length of the building and is a gap by design. Each one is a route for smoke. The reason sealant exists rather than mortar is movement: a rigid fill in a moving joint cracks within a season, and once it has cracked the rating is gone even though it still looks sealed. The work is in getting the joint geometry right — the right depth against width, the right backing rod, the right product for the substrate.

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Fire Retardant Sealants and Organic Sealants — Simfy Firesys

Detail

Where sealant is the right answer

Wall-to-floor junctionsWhere a compartment wall meets the slab above. A common and easily missed path for smoke between floors.

Expansion and movement jointsDesigned to move, so the seal must move too. This is where rigid fills always fail first.

Small service penetrationsA single conduit or a small pipe through a rated wall — a full mortar seal would be overkill and harder to re-open.

Head-of-wall detailsDrywall partitions meeting a deflecting slab. A gap that is meant to be there, and must still resist fire.

On site

What we check before applying

The substrateConcrete, block, drywall and steel do not all take the same product. Using one sealant everywhere is how you get adhesion failures.

Joint depth against widthThere is a correct ratio. Too deep and the sealant tears when the joint moves; too shallow and it has no fire performance.

Backing materialA backing rod or mineral wool sets the depth and stops the sealant bonding on three sides, which is what causes splitting.

Whether it is the honest choiceSometimes a joint is too wide or too busy for sealant and needs a different system. We say so rather than filling it and moving on.

FAQ

Questions we get asked about this

What is the difference between fire sealant and ordinary silicone?Ordinary silicone has no fire rating — it will burn through and leave the gap open. Fire retardant sealant is tested as part of a complete system: a stated joint size, substrate and depth, giving a stated resistance period.

How long do fire sealants last?Properly specified and applied, they last for the design life of the joint. What shortens it is movement beyond what the joint detail allowed, or later trades cutting through it.

Can sealant be used on large openings?No. Beyond the tested joint width, sealant is the wrong product. Large openings want mortar, boards or pillows depending on what passes through them.

Do you re-seal joints that another contractor did?Yes, and it is a large part of what we do. We check what is there first and tell you whether it needs replacing or only topping up.