Short answer
Check exterior joints at least once a year and after any leak. Look for edges pulling away, splits through the middle of the bead, and sealant that has gone hard or chalky. Isolated damage can be cut out and patched. Widespread hardening or edge failure means the whole run needs replacing.
Exterior sealant is a maintenance item. Sun, rain and daily movement wear it out, and in Singapore it gets plenty of all three. Regular checks let you replace joints on your own schedule, not after water comes through a ceiling.
Plan the walk-round
Mark the joints on an elevation drawing or a set of photos: window perimeters, panel joints, copings, parapets and penetrations. Note what’s on either side of each joint and when it was last sealed. Check at least once a year, and after a leak, façade cleaning, nearby works or a big storm.
Inspect only from safe access: the ground, balconies, a platform or a gondola. Don’t lean out of windows for a better photo. Binoculars or a zoom lens are fine for screening high joints. Anything you need to touch needs proper access.
What to look for
- Edge pulling away from one side: adhesion failure. Usually dirty or damp faces at installation, the wrong sealant for the surface, or a weak coating that let go.
- Split down the middle of the bead: cohesive failure. The joint moved more than the bead could take, because it was too thin, too narrow, or stuck to the back as well as the sides.
- Paint or render stuck to the back of loose sealant: the surface failed, not the sealant.
- Hard, chalky, crazed or shrunken sealant: it has aged out.
- Soft, sticky or stained sealant: possibly reacting with a gasket, bitumen or old sealant underneath.
Press a gloved finger on sealant that looks sound. It should feel rubbery and spring back. Sealant that has gone hard can’t take movement any more, even if it looks intact.
Note whether defects repeat: every sun-facing joint, every panel corner, every sill end. A pattern points to design or movement. Random defects point to workmanship. Our joint failure guide goes through each type.
Leaks aren’t always the sealant
Water can get in at one point and show up metres away. Before you reseal the nearest joint, check flashings, gaskets, cracked render, blocked drainage and weep holes. Never seal a weep hole. It is meant to be open.
If you water test, start at the bottom and wet one area at a time, so you know which joint let the water in. Hosing the whole wall tells you nothing.
Patch or replace?
Patch when the damage is local, such as an impact or a short length of lifted edge, and the sealant on either side is still rubbery and well stuck. Cut back to sound sealant, remove everything loose, clean the faces and fill. Try a small patch first to check the new sealant grips the old.
Replace the run when defects are widespread, the sealant has gone hard along the whole elevation, the same failure keeps coming back, or you don’t know what the old sealant is. A string of patches costs more in access than doing it once.
To replace, cut out all the old sealant, get the faces back to clean, sound material, fit new backer rod at the right depth and reseal. Test adhesion on the actual surfaces first. See how to test sealant adhesion.
Which Pereseal for exterior joints
For window perimeters, cladding and general weather joints we use Pereseal N. It is a neutral-cure, UV-resistant silicone that takes ±30% movement and bonds to masonry, concrete, glass, aluminium and most plastics. Keep it off copper.
Pereseal 802 is our acetoxy silicone for glass and metal glazing. Keep it off marble and natural stone. Neither is a structural glazing sealant.
Write down what you used, where and when. Next year’s inspection starts from that record.
Send us photos of the failed joint
A close-up and a wider shot of the elevation tell us most of what we need. We’ll suggest a repair and a sealant.
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