Would like to get the best suitable filler to repair the external wall crack, which wall filler do you suggested?
Welcome to the Bunnings Workshop community @Bosco. It's fantastic to have you join us, and many thanks for your question about repairing a crack.
That's a fairly substantial crack, so I'd recommend you have a professional assess the wall to ensure it is structurally sound. Provided the wall is in good shape and this crack is from movement that has been resolved you could look at filling the gap with a flexible caulking product such as Sika 310ml White Sikaflex Pro+ Polyurethane Sealant. You'll need to push some filler rod into the larger portions of the crack to prevent excessive product use.
After the Sikaflex has dried, you can paint over it.
The alternative would be to use a cement-based filler, which could more closely mimic the texture of the render. However, if the movement continues, it will crack again quickly.
Be advised that filling the crack is just an aesthetical repair and doesn't resolve the underlying movement issue.
Please let me know if you have any questions.
Mitchell
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