Dealing with Shrinking Gaskets in Veranda Roofs
The rubber gaskets that run between your glass panels and the aluminium frame are the unsung heroes of your veranda. However, like all rubber products, they can shrink over time due to UV exposure and extreme cold. If a seal 'pulls back' from a corner, it creates a small gap that can allow water to track into the frame.
Safety first: isolate power before touching a motorised system, and never work at height off a ladder alone. If in doubt, book a fitter rather than forcing a mechanism.
The nature of EPDM shrinkage
Most high-quality verandas use EPDM rubber, which is very durable but still susceptible to minor shrinkage over 10-15 years. This typically manifests as a gap at the very top or bottom of a glazing bar.
Spotting the tracks
You might not see a drip immediately. Look for dry water-marks or 'tide lines' on the inside of the aluminium profile. These often point directly to a seal that has pulled back by just a few millimetres.
- Check gasket ends for gaps
- Look for salt-like tide marks
- Feel for dampness in the profile
- Note if the leak only happens in heavy rain
Why DIY silicone fails
It is tempting to squirt silicone into the gap, but this is a temporary fix. Silicone doesn't bond well to old rubber, and the movement of the roof will eventually break the bond. The correct fix is to replace the gasket or add a specialist seal extender.
Professional gasket replacement
A technician can remove the top capping, pull out the old, shrunk gasket, and install a new, full-length seal that is slightly 'over-sized' to allow for future settling, ensuring a perfectly dry roof.
Corner joints versus straight runs
Shrinkage tends to show up first at corner joints and where two lengths of gasket meet, because these are the weakest points in the seal's continuity. A straight run of gasket rarely fails along its middle length; if you find a leak away from any joint, check whether debris or a sharp edge in the frame has cut the rubber rather than assuming general shrinkage.
Questions we get asked on repair calls
Can I pull the gasket back into place?
Usually no; if it has shrunk, it is now too short to reach both ends. It must be replaced with a new length of rubber.
Is this covered by my original install?
Seals are often considered maintenance items, though some high-end systems have very long-life gaskets.
Can I identify a shrinking gasket before it leaks?
Run a finger gently along the gasket line each spring; a section that feels noticeably harder, more brittle, or slightly recessed compared with the rest of the run is an early sign of shrinkage worth flagging before wet weather arrives.
Does gasket shrinkage happen faster on south-facing roofs?
Yes, sustained UV exposure accelerates the breakdown of rubber compounds, so panels that face south or receive long hours of direct sun each day are more likely to show shrinkage sooner than shaded or north-facing sections.
Will a new gasket look different from the surrounding rubber?
A freshly fitted gasket may look slightly darker or glossier than older, sun-faded rubber nearby at first, but this difference fades within a season as the new seal weathers naturally to match.
Interim measures while awaiting a fix
If a gap is spotted during wet weather and a repair cannot happen immediately, a strip of purpose-made flashing tape applied externally over the gap can reduce water ingress in the short term. This is not a substitute for gasket replacement and should be removed before the permanent repair, since adhesive residue can interfere with the new seal bonding correctly.
- 1Dry the area thoroughly before taping
- 2Apply flashing tape smoothly with no creases
- 3Avoid silicone as a long-term substitute
- 4Remove tape residue before the permanent repair
In short
Shrinking seals are a normal part of a structure's aging process; replacing them with fresh gaskets is the only way to ensure a dry interior.
Get it looked at
Noticed a drip from your roof seals? We can source and fit original manufacturer-spec gaskets.
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