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Step-by-step solution

Fire-rated joints

Joints in fire-rated walls and floors, such as stair and lift shafts, compartment walls and plant rooms, must hold back fire and smoke for the rated time. The rating comes from a tested configuration, not from the sealant alone.

  • 6 steps
  • 3 products
  • 4 answers
Joint between two wall sections sealed on both faces with orange fire-rated sealant, with flames on one side

Get this solution priced Proposal brief ↓

You need this when…

  • Open gaps at the head of fire-rated block walls
  • Ordinary silicone used in compartment wall joints
  • Fire officer or insurer asking for fire-stopping evidence
  • New hospital, hotel, plaza or high-rise needing fire-stopping

The work, step by step

General guidance based on the manufacturer data sheets. Site conditions differ: confirm the system with MCT before you start. Where we do not name a product, ask us and we will confirm the right one.

  1. Step 1: Confirm the rating and the tested system

    Agree the required fire-resistance time with the fire consultant. Design the joint from the test certificates (Sika Firerate p.2). For Sikaflex-400 Fire, joint design and backing material follow the approvals and the Sika Passive Fire Protection Handbook (Sikaflex-400 Fire p.2).

  2. Step 2: Prepare the joint

    The substrate must be sound, clean and dry. Repair damaged edges with Sika repair products, and saw-cut new joints (Sikaflex-400 Fire p.3). Do not apply Sika Firerate to damp or wet surfaces (Sika Firerate p.2).

  3. Step 3: Movement joints, inside and outside

    Sikaflex-400 Fire is a polyurethane fire-rated sealant for movement and connection joints and penetrations, with up to 4 hours of fire resistance (AS 1530.4, EN 1366-4) and ±35 % movement, for internal and external use (Sikaflex-400 Fire p.1). Prime porous substrates with Sika Primer-3 N or Primer-210 (Sikaflex-400 Fire p.3). Sikasil-670 Fire is a silicone with up to 4 hours (EN 1366-4), for joints 10–40 mm wide and up to 20 mm deep, at 2:1, over polyethylene foam backing rods (Sikasil-670 Fire p.1, p.2).

  4. Step 4: Interior joints in walls and partitions

    Sika Firerate is an intumescent acrylic for interior fire-rated joints, with up to 4 hours (AS 1530.4) and ±20 % movement (Sika Firerate p.1). Joints are 10–50 mm wide and no more than 10 mm deep, at 2:1, over polyethylene foam backing rods (Sika Firerate p.1, p.2).

    Sika Firerate Sika Request a quotation

    Sika® Firerate is designed for fire rated movement and connection joints on porous and non-porous substrates. (TDS p.1)

    Temperature stated in TDS
    −20 °C to +80 °C (TDS p.1)

  5. Step 5: Flame-retardant sealing (not a rated joint)

    A flame-retardant sealant is not a fire-rated joint. Where your fire consultant accepts a flame-retardant (not rated) seal, ask us. For any rated joint, use only a product with fire-resistance test evidence for that joint width and wall or floor type.

    Product for this stepAsk us

    The right product here depends on your site. We confirm it before naming it.

  6. Step 6: Record what was installed

    Keep the data sheets and classification reports with the handover file. The dimension and configuration limits in those reports must be met (SikaSeal-623 Fire p.2).

Proposal brief

Fire-rated joints: scope and system

A starting point for a site proposal. Quantities, prices and the final specification follow a site visit or photos.

Scope of work

  1. Review of the fire strategy and required ratings
  2. Survey and measurement of x running metres of fire-rated joints
  3. Backer material, priming and fire-rated sealant to the tested configuration
  4. Handover file with data sheets and classification reports

System build-up

StepProductPackSource
3. Movement joints, inside and outsideSikaflex-400 Fire—TDS p.1 · April 2021, Version 02.01
3. Movement joints, inside and outsideSikasil-670 Fire—TDS p.1 · December 2022, Version 04.02
4. Interior joints in walls and partitionsSika Firerate—TDS p.1 · May 2021, Version 01.01

What we need from you

  • Fire strategy drawing or the required rating (for example 2 hours)
  • Wall and floor types (block, RCC, drywall)
  • Joint widths, lengths and expected movement
  • Inside or outside?
  • Photos of typical joints

Site conditions

  • Joint sizes within the tested limits (Sikasil-670 Fire p.2; Sika Firerate p.1, p.2)
  • Dry substrates (Sika Firerate p.2)

Not included

  • Fire engineering design and authority approvals
  • Fire-stopping of pipes and cables (see the pipe penetrations guide)
  • Structural fire protection of beams and columns

Questions customers ask

How many hours of fire resistance?

Up to 4 hours in tested configurations: Sikaflex-400 Fire (AS 1530.4, EN 1366-4), Sikasil-670 Fire (EN 1366-4) and Sika Firerate (AS 1530.4) (each data sheet p.1). The actual rating depends on joint size and build-up (Sika Firerate p.2).

Is ordinary silicone enough?

No. Use a product with fire-resistance test evidence. Sika Firesil-N is flame-retardant, but its data sheet gives no fire-resistance time (Sika Firesil-N p.1, p.2). Ask us for the rated options.

Can the fire sealant be painted?

Sikaflex-400 Fire can be over-painted after a compatibility trial (Sikaflex-400 Fire p.2). Sikasil-670 Fire cannot be over-painted (Sikasil-670 Fire p.3).

Which one for an outside wall?

Sikaflex-400 Fire is for internal and external use (Sikaflex-400 Fire p.1). Sika Firerate is for interior use (Sika Firerate p.1).

Steps and product facts are taken from the manufacturer data sheets (page cited). Products are named only where the data sheet confirms the use; quantities follow a site visit or photos. General guidance: check the data sheet or ask us before you start.