Movement joint sealant fails for predictable reasons. Knowing those reasons – and what they look like in the field – helps contractors and facilities teams catch problems before they become bigger envelope or moisture issues. This article covers the main causes of failure and the visual signs to look for during inspection or refurbishment scoping.
Sealant ageing and material degradation
All sealant systems have a service life. Polyurethane and silicone movement joint sealants typically perform well for fifteen to twenty-five years depending on exposure and product grade. After that, UV exposure, temperature cycling and atmospheric pollutants slowly break down the material. The sealant becomes brittle, loses elasticity and starts to crack along the joint line. On older commercial buildings, age-related degradation is the most common reason a movement joint reaches the end of its useful life – even if no obvious damage event has occurred.
Joint movement exceeding sealant tolerance
Sealant systems are rated for a specific movement capability – the percentage of joint width the material can accommodate before failure. Where actual building movement exceeds the rated tolerance, the sealant fails earlier than its expected life. This often happens where the original specification did not account for the building’s true movement profile, or where structural settlement has gone beyond the design assumption. The visible sign is typically cohesive failure – the sealant tears within itself rather than at the substrate interface.
Poor adhesion at the substrate
Adhesion failure occurs where the sealant has not bonded properly to one or both sides of the joint. This usually traces back to installation – a contaminated substrate, missing primer where required, dust or moisture in the joint at application, or the wrong product specified for the substrate combination. The visual sign is adhesive failure: the sealant peels cleanly away from the substrate, often along long sections of the joint. Adhesion failures are particularly common on facades with mixed substrate joints, such as metal-to-stone or glass-to-aluminium.
Joint design and geometry issues
The geometry of a movement joint affects how the sealant performs. Joints that are too narrow restrict the sealant’s ability to flex. Joints that are too deep encourage the sealant to fail by stretching across an unsupported void. Missing or incorrectly positioned backer rods affect the sealant profile and bond surface area. Each of these design issues shortens the service life of the sealant. On commercial refurbishment projects, joint geometry is worth inspecting alongside the sealant condition itself – the joint may need adjustment rather than just a like-for-like reseal.
Visual signs to look for during inspection
Practical inspection signs cover most failure types. Look for cracking along the centre line of the sealant, splitting or tearing across the joint, sealant pulling cleanly away from one substrate, brittle or chalky surface texture, discolouration darker than the original product, and visible gaps where weather can penetrate the building envelope. On internal floor joints, lifted edges and missing material are common. Photographing affected joints with a reference for scale helps a sealant specialist quote accurately for resealing scope without a second visit.
Where movement joints show any of these signs across a building or estate, our movement joint sealant services cover specification, resealing and replacement across UK commercial portfolios.
Talk to SD Team about your project
If you have movement joints showing signs of failure across a commercial building or estate, SD Team can inspect the scope and confirm a resealing plan. Get in touch to discuss the buildings, the joint locations and the programme window for the work.
