Independent comparisons. We may earn from shop links. More info

Replace a uPVC window seal in the sash groove

Updated: October 2026

On an older uPVC casement the groove rubber has gone hard, and a draught tracks the lock side. You can replace a uPVC window seal yourself only when that strip pulls out by hand and a short sample seats in the same slot. If it is clipped against the glass, or welded into the frame, a fitter should see it before you buy a coil. The [window seal comparison](/hub/door-and-window-security/window-seal) sets Storm Patrol and Tarqite side by side. Products Compared read those amazon.co.uk listings on 15 October 2026 and did not fit the coils on a test rig. A qualifying purchase can earn a commission at no extra cost to you.

On an older uPVC casement the groove rubber has gone hard, and a draught tracks the lock side. You can replace a uPVC window seal yourself only when that strip pulls out by hand and a short sample seats in the same slot.

Our top picks

Storm Patrol Storm Patrol uPVC gasket, 25 m, black

Best overall

Storm Patrol Storm Patrol uPVC gasket, 25 m, black
7.5/10about £20.18
View offer
Tarqite Tarqite uPVC gasket, black

Alternative

Tarqite Tarqite uPVC gasket, black
4.6/10about £7.89
View offer
YANKUIRUI YANKUIRUI D-profile foam seal, 6 m, white

Rank 3

YANKUIRUI YANKUIRUI D-profile foam seal, 6 m, white
8.6/10about £4.49
View offer
On this page
  1. 1.Compression gasket or glazing gasket
  2. 2.Sample the foot in the groove
  3. 3.Feed it in without stretching
  4. 4.When to stop

Compression gasket or glazing gasket

A compression gasket is the bubble or flipper between sash and frame, and it pulls out by hand once a corner lifts. A glazing gasket is the wedge or U-channel held against the glass by a bead. A bubble coil for that edge is the usual wrong buy. Fixtrade treats a brittle bead as a fitter's job, before a snapped bead can free the double-glazed unit. If the glass stays put when you lift a short length, that is the pull-out seal. A seal built into the frame cannot be tugged out. A rebate with no groove is stick-on work, set out in how to fit a window seal.

Sample the foot in the groove

The foot is the stem that locks into the groove. Two seals can share a bubble and still miss when the stems differ. Seals Direct says to measure the channel opening, and to look for a bubble about a third higher than the gap. The window seal buying guide sets out the same check. Neither listing prints a foot width. Storm Patrol (B0CDVH313Y) was about £20.18 for 25 m, rated 4.5 from 306 reviews, for frames stated as 3–5 mm. Tarqite (B0G2LCQH6S) was about £7.89, rated 4.5 from nine reviews, and states no gap. Its title says 6 m, the unit count says 8 m, and the item length says 80 cm. If a short piece does not seat, it is the wrong gasket.
Storm Patrol Storm Patrol uPVC gasket, 25 m, black

Testsieger

Storm Patrol Storm Patrol uPVC gasket, 25 m, black
7.5/10about £20.18
View offer

Feed it in without stretching

Once the sample seats and the sash still closes, clean the groove and keep adhesive, silicone and lubricant out of it unless that maker says otherwise. Use a scraper only where the listing allows it, as Storm Patrol does for a tight groove. Press the coil in from a top corner, slightly full, with no tug. Fixtrade calls stretched rubber the usual reason a corner opens weeks later. Butt the square-cut ends. If the lock misses, peel it out. A damaged groove is covered on the foam window seal or gasket page, and foam will not rescue a bad foot.

When to stop

Stop if the seal is welded in, if the bead is brittle, if the sash has dropped, or if the frame is badly distorted or in a listed building. A taller bubble will not lift a dropped sash. Mist between the panes is a failed sealed unit, so a new gasket does not clear it. If a trickle vent might feed an open-flued fire or boiler, leave that air path open. Storm Patrol states 3–5 mm frames and 25 m, and still publishes no foot width. Tarqite states neither the gap nor one length. YANKUIRUI is the stick-on D-seal, for a rebate with no groove.

Common questions

Can I replace the rubber without taking the glass out?
Yes, if the compression seal pulls out of the groove by hand. Leave the glass and the beads in place, close the sash on a short sample, and only then run the perimeter. A seal under a bead, or one welded into the profile, is a different job. Fixtrade treats a brittle bead as a stop, because levering it off can free the double-glazed unit.
How do I tell a weather gasket from a glazing gasket?
A weather gasket, a bubble or a flipper, sits between sash and frame and comes out in one length. A glazing gasket, a wedge or a U-channel, bears on the glass under a clip-in bead. If you have to move the bead before the rubber lifts, leave the draught coil unopened.
What if the new foot will not sit in the groove?
The section is wrong for that slot, and extra pressure will not change the stem. Take the sample out and measure the channel opening before you order again. A scraper will not widen the channel. Neither coil prints a foot width.
Should I stretch the coil so it looks tight?
No. Lay the rubber in slightly full and let the foot hold it. Fixtrade says tension is why a corner opens weeks later, after the coil shortens. If you are short of the perimeter, you need more coil. Stretching a 25 m reel only shifts the gap to the corner.
Do I glue the joint?
No. Butt the square-cut ends so the sash meets a flat line. Fixtrade keeps adhesive, silicone and lubricant out of the groove unless that maker says otherwise. A silicone dab leaves a lump the sash rocks on.
Will a new gasket clear mist between the panes?
No. Mist between the panes means the sealed unit has failed. Groove rubber only closes the gap around the opening. A matching gasket can still cut a draught if the foot seats and the handle turns, and the mist stays.

Related pages

Mist between double-glazed panes

Window seals

Best window seal for a groove or a stick-on rebate

Window seal buying guide: measure the gap in millimetres

Foam window seal or a gasket: which one should you buy

How to fit a window seal so the handle still locks

Sources

Public UK sources named in the research digest. Listing prices and ratings are the amazon.co.uk figures saved on 15 October 2026.

  1. Energy Saving Trust — Draught-proofing (retrieved October 2026)
  2. Centre for Sustainable Energy — DIY draught-proofing (retrieved October 2026)
  3. GOV.UK — Approved Document F (2026) (retrieved October 2026)
  4. BSI — BS EN 12365-1:2003 gasket and weatherstripping (retrieved October 2026)
  5. Seals Direct — How to measure a replacement glazing gasket (retrieved October 2026)
  6. Fixtrade — How to replace the rubber seal on uPVC windows (retrieved October 2026)
  7. Historic England — HEAG084 Draught-proofing windows and doors (retrieved October 2026)
  8. Consumer Rights Act 2015 (retrieved October 2026)