Sikaflex®-400 Fire

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Updated: June 24, 2019

You really can’t afford to muck around when it comes to building and fire ratings. All your materials need to be able to stand up to the heat and flame that could come in the form of a bushfire or home fire.

There are a lot of building materials that offer great resilience on this front. Sikaflex®-400 Fire is one product that brings together moisture-curing, elastic joint sealing and fire resistance. It is suitable for connection joints and penetrations on porous and non-porous substrates. It’s also suitable for interior and exterior applications. MOVER Sikaflex®-400 Fire is, as the name suggests, a top-shelf, fire-rated joint sealant in the form of a 1-part polyurethane sealant. Being packaged in a 600ml foil pack, it’s easy to use and apply with your sausage-gun applicator. The product itself is grey and application is very similar to other Sikaflex® products. Being easy to smooth and allowing good workability, you will find good adhesion to many different materials and substrates. The beauty of this product is it has a movement capability of ±35% (ASTMC719).

Test #1: Application

With the main feature being the passive fire protection, which is covered through official testing according to AS1530.4, this was always going to be a slightly difficult product to test. That being said, we were also keen to see how the product applied. Sikaflex®-400 Fire has a nice, soft consistency which is still firm enough to hold its form and not run or sag. We grabbed some hardwood and a sheet of plywood which we screwed together to form a join on an edge. We figured we would let the product cure the stated 24-hour time frame, then come back and hit it with some flame from our Hot Devil oxy kit at various levels of intensity to see how the product performed.

  • Up to 4 hours fire resistance according to AS1530.4
  • Up to 4 hours fire resistance according to EN1366-4
  • Movement capability of ± 35% (ASTMC719)
  • Easy to smooth and very good workability
  • Good adhesion to many different substrates
  • Long open time

Test #2: Fire

To test the fire-resistant qualities of the Sikaflex®-400 Fire I looked straight to my Hot Devil Trade gas torch. The temperature of this flame is significantly higher than normal fire conditions. We allowed Sikaflex®-400 Fire to cure, and some three days later had the chance to fire up the Hot Devil and put the sealant product to the test.

In our fire test set up, we put the intense flame straight onto some sections of an outdoor concrete paver we’d cut into strips. We used Sikaflex®-400 Fire as a joint sealant and let it squish out from the sections of pavers like bricks. The flame was held right on the product, and we moved the flame around in a circular motion. The intense flame put a black crust on the joint after about 10-15 seconds of focused exposure, but after the crust formed nothing else really happened. After about two minutes we turned off the Hot Devil to assess the damage. We let the joint cool, broke the crust and found the same grey-coloured Sika® sealant as was on the original top layer. After the scorching we’d given it I was very impressed.

Next, it was time to do the test on the timber set up we had prepared. The flame instantly started to scorch the ply/hardwood joint. This joint had much less excess product and was more typical of an actual join of various timbers. The plywood instantly blackened but Sikaflex®-400 Fire stayed true as I moved the flame back and forth over the test area. Eventually, the hardwood started to catch fire, the plywood was starting to charcoal, and the Sikaflex®-400 Fire had developed a good crust. Other than that it still hung tough.

A further check on the joint once things had cooled showed it was only the top layers of the joint that were crusting. Underneath showed the product was still intact and showing the same structure and consistency it had started with.

The Good, The Bad And The Ugly

When using a product like Sikaflex®-400 Fire the ugly doesn’t come into play. After completing our test, it became pretty clear that the Sika® product was going to outlast the material around it in the setup we created. The plywood and hardwood were well and truly going up in flames while the Sikaflex®-400 Fire showed very impressive resilience to the brute power of the Hot Devil Trade Map Torch. After seeing this product firsthand in our tests, I found myself asking the question: “Would I trust this product on my home?” The honest answer would have to be a confident, “Yes”.

For more information visit www.sikaretail.com.au