How to fix a fibre cement crack at a join?

[Lawzy]

I'm hoping the community can assist with their experience. I have an external building clad in fibre cement (I assume to be blue board). It has been up for approximately 10 years and the wind/weather has caused one of the board joins to crack, letting in moisture. I am trying to determine the best process to fix and seal the crack. What is the best approach and materials needed? Thanks in advance for any advice.

[MitchellMc]

Hi @Lawzy,

Could you tell us a little more about where this crack is located and how the water enters it? If it's on a verticle surface, you might get away with chipping out any deteriorated material and filling the crack with a repair cement like Dunlop 5kg Ardit Rapidset Repair Mortar. The product can be simply trowelled over and pushed into the crack and sanded back flush with the surface before re-painting.

If this is on a horizontal surface and water is pooling and entering the crack, then we'd need to look at a more permanent solution.

I'll be looking forward to hearing further details and assisting with any questions you have.

Mitchell

[Lawzy]

Thanks @MitchellMc

The image is a horizontal join on a vertical wall and exposed to the weather. Rain is seeping through and over time the internal frame is getting wet. I believe your solution lines up with the challenge and I'll give it a shot, thanks.

Chris.

[MitchellMc]

Goodluck, @Lawzy, and please shout out if you get stuck or need further assistance.

Mitchell

[Lawzy]

To wrap up this question, I removed the old and added new synthetic reinforcing tape, and sealed it with the rapid set mortar. That did the job nicely.

[MitchellMc]

Great solution, @Lawzy! Many thanks for getting back to us and letting us know the method you used.

Mitchell