What is the best gap filler to use on blue board
Welcome to the Bunnings Workshop community @ac1977. It's fantastic to have you join us, and many thanks for your question about filling the gaps between blueboard sheets.
Are these large gaps or very fine gaps? Perhaps you might like to show us some images of what you would like to fill.
The gap between sheeting is normally set with Dunlop 3kg Fibre Cement Jointing Compound and Builders Edge 50mm x 90m Alkali Resistant Render Fibre Cement Tape in much the same way Gyprock plasterboard sheets would be. The tape is used to prevent the jointing compound from cracking. I'll include a video below which shows the process on interior Villaboard sheets as it's a similar method.
Please let me know if you have any questions.
Mitchell
Hi Mitchell,
@ac1977,
That's a gap that should probably have been set originally with the above-mentioned products. Now, your best option might be to use a flexible and paintable polyurethane sealant like Sika 300ml White Sikaflex 11FC Plus Polyurethane Adhesive Sealant. It's a great product for joints that might expand and contract.
Can you tape the blueboard joint then patch of compound?
Hi @ac1977 if your looking for a basic cosmetic fill, James hardy make a product called a "Horizontal Trimline Joint Flashing" which come in various widths and 3m lengths and can be ordered via the special orders desk at your local Bunnings. It's pressed into position and fixed with silicone sealant.Regards, Nailbag
Hello @bob1234
Welcome to the Bunnings Workshop community. It's sensational to have you join us.
If you are using the Builders Edge 50mm x 90m Alkali Resistant Render Fibre Cement Tape, you can place the tape over the blueboard before using the patch compound.
If you need further assistance, please let us know.
Eric
Eric,
thank you for your help. I am using the tape you mentioned and Dunlop joint and patch on Blueboard with the aim of applying a Dulux texture paint. Is the joint patching product the most suited and will the jointing show with the texture paint? Also is the Dulux fine texture paint the most suited.
thank you in advance
Hi @bob1234,
The Dunlop 3kg Fibre Cement Jointing Compound is suitable for setting your Hardietex; Hardie's does not supply a specific product for this.
Provided you set the joint so it is flush with the elevated portion of the board and sand the finish smooth, the joints should be virtually invisible once you apply textured paint. The Dulux fine texture is certainly suitable, but it's more about what you'd like the finish to look like. The fine texture will give a small amount of texture, mimicking a fine render. If you wanted more of a rough-looking render finish, you'd need to go for the medium or full-cover texture.
Hi, I have just used this product to set some blue board joints … I could not quite get a flush finish, does that matter in terms of weather proofing etc?
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
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,
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
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 .
