Many building leaks are not caused by big failures but by small ones: a sealant joint that has cracked, shrunk or come unstuck. Sealants around windows, between panels, at balcony edges and across expansion joints have a limited life, and when they fail, water gets straight in.
Where sealants and joints are found
- Around window and door frames.
- Between facade panels and at changes of material.
- Expansion and control joints in walls, slabs and podiums.
- Balcony edges, balustrade fixings and thresholds.
- Roof and parapet flashings.
Signs of failure
- Cracked, hard or shrunken sealant.
- Sealant pulling away from one side of the joint.
- Gaps, missing sections or plants growing in joints.
- Leaks or staining near windows and joints after wind-driven rain.
Why they fail
UV exposure and weather age sealants. Joints that are too narrow, too deep or bonded on three sides cannot move properly and tear. Painting over flexible sealants, or using the wrong product for the movement, shortens their life.
How joints are replaced properly
- Remove the old sealant completely and clean the joint faces.
- Prime where the product requires it.
- Install a backing rod so the sealant bonds on two sides only and can stretch.
- Apply a sealant suited to the movement and exposure, tooled to the right profile.
- For expansion joints, install a proper joint system rather than a bead of sealant.
Joint and sealant replacement
On multi-storey buildings this is usually done from scaffold, swing stage or rope access alongside other facade repairs. See our waterproofing service or call 0415 840 500.
Frequently asked questions
How long do building sealants last?
It varies with the product and exposure, but sealants age and should be inspected regularly and replaced when cracked, hard or debonded.
Can new sealant go over old sealant?
No. The old sealant must be removed and the joint cleaned, or the new sealant will not bond.
Why do expansion joints leak?
Because the joint system or sealant has failed, or was not designed for the movement it has to take.
