Water on the floor at the end of a shower door is usually blamed on the bottom sweep. More often it arrived at the side: it ran down the closing edge, crossed the vertical gap beside the wall or the hinge, and only then spread along the floor. Side seals fail differently from bottom seals, and they are chosen differently too.
Before choosing a strip, it is worth confirming where the water is coming from: a side leak and a hinge-line leak look identical by the time they reach the floor. That diagnostic sequence is covered in why water escapes at the shower door hinge side. This article assumes that check is done and deals with the strip itself.
Measuring the Door-Edge-to-Wall Gap
Three measurements choose the strip: the glass thickness, the height the seal has to run, and the width of the gap with the door closed. Measure the gap at the top, middle and bottom of the closing edge, because hinged doors change that dimension as they are adjusted and sliding doors change it as they travel.
| Measurement | How to take it | Why it matters |
|---|---|---|
| Glass thickness | Calipers on the panel edge | The gripping channel is made for one thickness |
| Seal height | From the base line to the top of the door edge | Strips are cut to length and should not be stretched |
| Gap width | Door closed, at three heights | Decides profile depth and whether a fin or a bulb is needed |
| Fixing type | Channel, adhesive or compression | Determines what will stay in place on a moving edge |
Where the gap varies by more than a couple of millimetres from top to bottom, the door is out of adjustment rather than the seal being wrong. Correct the hinge or the roller alignment first, then measure again; otherwise the new seal is being asked to close a gap that changes shape.
Where Side Seals Differ on Hinged, Bi-Fold and Sliding Doors
On a hinged door, the side seal runs along the closing edge - the edge that meets the wall or the fixed panel - and it is the only barrier when the door is shut. On a bi-fold arrangement, the seal sits between folding panels and has to tolerate movement at the pivot. On a sliding door, the vertical seal usually runs along the leading edge of one panel and closes against the trailing edge of the other, and it has to survive the panel travelling past it several times a day.
The consequence is that the same profile rarely suits all three situations. A sliding door wants a profile with enough flexibility to recover after being compressed against the mating panel, while a hinged door can use a stiffer fin because the joint closes in one movement and stays closed. On a tub installation the side seal may need to run to a lower base line than on a shower base.
Fitting a Vertical Strip Without Trapping the Door
A vertical seal that is too thick will push the door open. The symptom is subtle: the door appears to close, but the closing edge rests slightly proud of the jamb, the bottom seal no longer compresses against the base, and the leak simply moves to the bottom. Fitting therefore starts with the door correctly adjusted and ends with a full travel check.
Work in this order. Clean the edge and the glass face of old adhesive. Dry-fit the strip along its full height with the door closed. Check that the door still latches or closes fully without the strip binding. Mark, cut once with a sharp blade, and fit from the top down so the strip is not stretched. Then open and close through the full travel and confirm the strip compresses and recovers rather than folding over. For adhesive-backed profiles, leave the door open for the first hours so the adhesive can set uncompressed.
When the Fix Is a Wall Profile Instead of a Seal
Some doors do not have a reliable closing edge at all. A sliding panel that ends beside a tiled wall with no jamb has nothing to seal against, and an adhesive strip on the panel edge will simply wipe across the tile and either drag or leave a gap. In those cases a wall profile - a vertical extrusion fixed to the wall - provides both a landing surface and a channel for a seal to run in.
A wall profile also solves a secondary problem, which is that a sliding door with no jamb tends to rattle and drift. Free-standing glass on a sliding panel needs something to stop it moving laterally at the closing edge, and a profile does that job while carrying the seal. Where the wall cannot take a vertical fixing because of the tile substrate, the alternative is a fixed panel at the end of the travel with a glass-to-glass joint, which converts the moving edge into a stationary one. Fixing requirements and substrate rules come from the adopted building code, published at iccsafe.org, and the waterproofing behind the fixing is described in methods from the Tile Council of North America and in the assemblies catalogued on the Whole Building Design Guide.
Cleaning and Replacing Side Seals
Vertical seals collect mineral scale on their lip because water sits against them whenever the door is closed. Wiping the lip with the same cloth used on the glass, and rinsing it after any cleaning product is used, extends life more than any additive. A seal that has turned stiff and white along the lip is usually recoverable with a mild descaler; one that has cracked at the fold is not.
Replacement is a fifteen-minute job once the measurements are right, and there is no reason to do it with the door removed. Lift the old strip out, clean the channel or the glass face, dry-fit the new one, and cut to length in a single pass. Leaving the strip slightly long and trimming after fitting is a reliable way to end up with an uneven edge, so measure twice and cut once.
Choosing Seal Length for a Sliding Door vs a Hinged Door
Seal length is set by the height of the gap being sealed, not by the height of the door. On a hinged door, the strip usually runs from the base line to the top of the opening, because that is the full extent of the closing edge. On a sliding door, the strip often stops below the head rail, since the rail occupies the top of the panel, and it may start above a bottom guide.
Two practical rules follow. Cut the strip to the gap, not to the panel, and confirm that nothing in the travel path - a stop, a guide, a towel bar fixing - sits where the strip will pass. Where a seal has to be replaced repeatedly at the same point, the cause is usually mechanical: a stop that is set too far, a panel that drops as it travels, or a door adjusted so the closing edge sits out of plumb. Hardware durability expectations and test methods for these components are described by the Builders Hardware Manufacturers Association and published through ASTM International. Where a side seal has been leaking for a long period, water will have reached the wall behind, and the EPA moisture guidance explains what that means for the assembly.
FAQ
What are the different types of vertical shower door seal strips?
The main families are fin or wipe strips that deflect water, bulb profiles that compress against a surface, magnetic strips that hold a sliding door closed against its partner panel, and rigid jamb seals that close against a wall profile. Material is usually PVC, silicone or EPDM, and the fixing is channel-held, adhesive-backed or compression.
How to choose the right shower door seal strip?
Match four things: glass thickness, the height of the gap, the width of the gap with the door closed, and how the strip is held in place. Measure at three heights, because a gap that varies means the door needs adjusting first. A strip that is too thick holds the door off its latch and simply moves the leak.
How to replace a shower door seal strip?
Remove the old strip, clean the channel or the glass face of adhesive residue, dry-fit the replacement with the door closed, then cut it once to length and fit from the top down without stretching. Check the full travel of the door afterwards, and leave adhesive-backed strips uncompressed for a few hours so the bond sets.
What is the rubber strip at the bottom of a shower door called?
It is called a bottom seal, sweep, wipe or drip strip depending on the manufacturer, and it is a different part from the vertical side seal covered here. Both are usually replaced as a set, because they wear at the same rate and a leak that appears at the bottom corner often starts at the side.
Send the glass thickness, the height of the closing edge and the gap at three heights with a photo of the edge, and we will confirm the strip and fixing that fits.
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