Expansion joints exist for a reason: buildings move, and without a correctly detailed movement joint, that movement becomes cracks, water ingress, and structural damage. The sealant within an expansion joint is a critical building envelope component — it needs to be the right product, the right size, applied correctly, and bonded only to the correct surfaces.
Sycamore Sealants has extensive experience with expansion and movement joint sealant application across commercial and residential projects throughout South East England. We work from design team specifications or can advise on appropriate product selection for your specific substrate and movement requirement.
Expansion Joint Services
- External Façade Joints — Movement joints in brickwork, render, cladding systems, and concrete panels. Correctly bonded, with appropriate backer rod sizing.
- Internal Floor Joints — Expansion joints in floor screeds, tiled floors, and resin floors. Flexible product selected for the expected foot traffic and movement.
- Structural Movement Joints — Larger movement joints requiring specialist flexible sealants with high movement accommodation. Experience with both new build and refurbishment projects.
- Curtain Wall & Glazing Joints — Joints between glazing systems and surrounding structure. Structural silicone and weatherseal applications.
- Listed Buildings — Sympathetic product selection for heritage and listed structures where standard products may be inappropriate. Experience working under conservation officer guidance.
- Re-Pointing & Joint Replacement — Removal of failed or deteriorated joint sealant, full preparation, and re-application. Including cutting back old sealant and backer rod replacement.
Getting the Specification Right
An expansion joint only works if it's specified correctly. The key considerations are movement accommodation (how much the joint needs to stretch and compress), substrate compatibility, and UV and weather resistance for external applications.
We work with polyurethane, polysulphide, and silicone sealants depending on the application. We carry backer rod in a full range of diameters and can advise on correct joint width-to-depth ratios. If a design team specification exists, we follow it. If not, we'll advise on appropriate products based on the site conditions.
Why Correct Application Matters
The most common cause of expansion joint failure is three-sided adhesion — where the sealant bonds to the backer rod or joint base as well as both sides. This prevents the sealant from moving correctly and leads to early failure. Our operatives understand this and apply bond breaker tape or foam backer rod as appropriate on every job.
Frequently Asked Questions
What's the difference between a mastic joint and an expansion joint?
In general usage, 'mastic' refers to any flexible sealant joint, while an expansion or movement joint is specifically designed to accommodate structural movement. The key difference is in the product specification and application detail — movement joints require two-sided adhesion only, and the product must be rated for the expected movement.
Can you work from a design team specification?
Yes. We're experienced reading and following architects' and engineers' joint specifications. We'll flag any issues or conflicts on site rather than applying a product we're not confident is correct.
How long does expansion joint sealant last?
A correctly specified and applied expansion joint sealant should last 15–25 years, depending on the product type and exposure conditions. Silicone typically outperforms polyurethane in UV-exposed external applications. We can advise on expected service life when quoting.
Do you remove and replace failed joint sealant?
Yes. Removal of old sealant, cutting back, backer rod replacement, surface preparation, and re-application is a standard service. We don't apply new sealant over old — it doesn't work and leads to early failure.