Façade defects · Water ingress
Failed sealant joints: causes, risks and repair.
How sealant joints between panels and around windows fail, why they fail long before the façade, and how a close-up survey plans their replacement.
| At a glance | |
|---|---|
| What it is | Mastic or silicone joints between panels, around frames and at movement joints that have cracked, hardened or come away. |
| Main risk | Water ingress, and on structurally glazed façades, a safety question about the glass. |
| Common on | Offices and apartment blocks over about 10 years old. |
| Usually spotted by | Condition surveys and planned maintenance inspections. |
What sealant joints do
Sealant joints close the gaps between façade components while letting them move with temperature and wind. They are among the shortest-lived parts of a façade, so most buildings need them renewed several times over their life. Structural silicone, which bonds glass to its frame on some façades, is a different and safety-critical joint.
How to recognise it
- Cracks along the joint or through the sealant.
- Sealant that has pulled away from one side.
- Hard, chalky or shrunken sealant.
- Gaps, missing sealant or exposed backing rod.
- Dirt streaks and staining below joints.
Why it happens
- Age and sunlight.
- Joint movement beyond what the sealant can take.
- Poor surface preparation or missing primer.
- Sealant bonded on three sides, with no bond breaker at the back.
- Sealant incompatible with the materials either side.
Why it matters
- Water ingress into the wall and building.
- Safety on structurally glazed façades, where the joint helps hold the glass.
- Planning. Joint replacement needs access, so it is cheapest when planned with other works.
How we investigate it
We inspect joints at arm's length from the building maintenance unit, powered access or walkways, rather than relying on binoculars. We record joint widths, adhesion and condition, check gaskets and pressure plates nearby, and pin every observation to its location on the elevation drawings. The report covers each façade system in turn, with recommendations and budget costs.
How it is put right
- Rake out and reseal with a compatible sealant, primer and backing rod.
- Specialist review of any structural silicone joints.
- A planned programme of joint renewal, timed with other access.
From our investigations
Examples from our own work. Client and building details are withheld.
See our published case studies
What to send us
The address, the building's age, photos of any failed joints, and any previous condition or maintenance reports. Email enquiries@mtconsult.co.uk, use our contact form or call 0800 048 5229. We typically respond within one working day.
Frequently asked questions
How long do sealant joints last?
It varies with the product, exposure and movement, but usually far less than the façade itself, so renewal should be planned.
Can joints be inspected without scaffolding?
Yes. We use the building maintenance unit or powered access.
Should joint replacement be part of planned maintenance?
Yes. Our planned maintenance inspections set when and where joints need renewing.
Related
Talk to us
Joints past their best?
Our in-house contracting team provides the access and opening-up, so you have one point of contact.