Best filler for gaps in blueboard joins?

[ac1977]

What is the best gap filler to use on blue board

[Nailbag]

Hi @tobes it shouldn't affect the waterproofness if you have flooded the advice of both @EricL and @MitchellMc. It would simply be just cosmetic.

Nailbag

[pgeee]

I note that the recommended joint compound has awful reviews on Bunnings site, so I need to find something else that can act like a plasterboard jointing compound but have good reviews,

[JacobZ]

Hi @pgeee,

You can use this James Hardie Base Coat Compound instead, but please note that it is a base coat compound that is used in conjunction with Paper Jointing Tape as the first layer of a jointing system. Base coats are supposed to set really hard and create strength, so they are not easily sandable. They are there to provide strength to the joint.

If you are looking for a paintable finish, you need to apply a topping compound like this James Hardie Top Coat Compound over the top before sanding and painting.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob

[pgeee]

Thanks. Yes I’ve used a topping compound before externally. It will last a while under a good external primer and  paint but i wish there were a dedicated external  equivalent .