Best caulk for external masonry joints that actually lasts?

brickworkboss_wm

Bricklayer

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Working on a domestic extension, brick cavity wall. Movement joints at window reveals need caulking. Used a standard silicone on a previous job and it failed within 18 months, client not happy. What sealant are people using for external brick/render movement joints that actually stands up?

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3 replies

roofer_robbie_midlands

Roofer

1y ago

Fosroc Expandafoam for wider joints, then Soudal PU over the top. Makes sure the sealant isn't bridging too wide a gap. Silicone fails because people stuff it in dry joints with no backer, it can't do the movement cycle.

tradefinisher_trev

Painter & Decorator

1y ago

Soudal SWS or equivalent polyurethane sealant. Not silicone. Silicone doesn't take paint and it fails in UV especially on south-facing elevations. PU sealant is paintable, more flexible, UV stable. Backer rod in first so you get the right geometry (2:1 width to depth), then the PU sealant tooled in. Done properly it should last 10-15 years.

brickworkboss_wm

Bricklayer

1y ago

Never used PU sealant, only ever used silicone. Makes sense on the paintability point, client always wants it painted over. Will switch to Soudal SWS. Cheers.

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