How do you fix cracks in rendered blueboard?

[#1]

Cracks between boards in rendered blueboard cladding can be caused by ground movement, installation issues or environmental factors.

Some cracks can be managed with fillers and cover-ups, but extensive damage may necessitate resetting joints entirely with tape.

Begin by examining the extent of the cracks and preparing the surface by cleaning and removing debris. 

For minor cracks, you can chase them out and widen them slightly with a chisel or angle grinder for better filler adhesion. Then, use a high-quality cement filler such as Gripset Betta Concrete Gap filler or polyurethane sealant like Sikaflex 11FC to fill the widened cracks.

Alternatively, Hardieflex strips attached with construction adhesive and clouts can be used to disguise the area, with clouts being less likely to cause cracking than screws. Another option would be to utilise Brutus 50 x 6mm x 2.4m Building Moulding Cover Trim, which shares similar thickness to Hardieflex, but features a smooth surface.

In cases of severe damage, resetting joints with reinforcement tape may be necessary. This involves removing existing render, applying tape, and re-rendering for a seamless finish.

Once the crack repair is complete, you can prime the area with an undercoat suitable for masonry and, once dry, coat the surface with exterior paint.

Please remember your personal protective equipment when conducting repair work, including a face mask, goggles and protective gloves. - MitchellMc