Fix a Shower Door That Leaks at the Side
Quick answer
Side leaks split into two cases. Hinge-side leaks come through the gap between the door glass and the wall or fixed panel it pivots from — fixed with a soft vertical side seal, bulb seal, or finned u-channel. Handle-side leaks escape where the door closes against a wall or panel — fixed with a magnetic pair or a flexible strike-side flap. Identify which edge drips before buying anything.
Data reviewed:
Likely causes and how to recognize them
| Cause | How to recognize it |
|---|---|
| Hinge-side gap | A visible vertical slit between the pivoting edge and the wall/panel; spray hits it directly. |
| Handle-side strike gap | The closing edge stops short of the wall or panel; the old magnet or flap no longer meets. |
| Failed vertical seal | An existing side seal is torn, shrunken (gaps at top or bottom), or has fallen off. |
| Door out of plumb | The vertical gap is wider at the top than the bottom, or vice versa — a hinge alignment issue. |
Step-by-step fix
- Find the wet edge. Run the shower aimed at the door and watch each vertical edge from outside. Mark the one that drips.
- Measure the vertical gap. Top, middle, bottom. Under 3/16 inch and even: a flat flap seal. Up to 1/2 inch or uneven: a bulb seal that compresses to fill variation.
- Match glass thickness. Vertical seals grip the glass edge the same way sweeps do — the channel must match 1/4, 3/8, or 1/2 inch glass.
- Pick the closure type. Hinge side: flap, bulb, or finned u-channel. Handle side to wall/panel: magnetic pair (replace both halves) or wide soft flap.
- Cut to height and install. Trim to door height minus 1/16 inch, keep the sweep clearance at the bottom, and press on dry — vertical seals should not be lubricated or they slide down.
What to measure before buying
- Glass thickness at the bare edge — pull back a section of the old seal first (1/4″, 5/16″, 3/8″, or 1/2″)
- Bottom gap from glass edge to threshold at the HINGE end, door closed
- Bottom gap at the HANDLE end, door closed — note any difference
- Door width along the bottom edge (for trimming the new seal)
- Where the water actually exits: under the door, off a bottom corner, or down a vertical edge
- Photo of the old seal's cross-section before removing it
Seal types that fix this
Matching replacement seals
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Shower Door Bulb Seal, 1/4 in Glass, 1/2 in Bulb, 72 in
- Glass
- 1/4″
- Gap
- 1/8–1/2″
- Length
- 72″
- Material
- PVC bulb on PVC channel
- Mount
- press-on
- Trim
- Cut to size
Hollow bulb compresses to follow a wall that is out of plumb — pick a bulb about equal to the widest point of the gap. Install dry, top down.
Shower Door Bulb Seal, 3/8 in Glass, 1/2 in Bulb, 72 in
- Glass
- 3/8″
- Gap
- 1/8–1/2″
- Length
- 72″
- Material
- PVC bulb on PVC channel
- Mount
- press-on
- Trim
- Cut to size
Hollow bulb compresses to follow a wall that is out of plumb — pick a bulb about equal to the widest point of the gap. Install dry, top down.
Silicone Shower Door Bulb Seal, 3/8 in Glass, 5/8 in Bulb, 72 in
- Glass
- 3/8″
- Gap
- 1/8–1/2″
- Length
- 72″
- Material
- Silicone bulb on polycarbonate channel
- Mount
- press-on
- Trim
- Cut to size
Hollow bulb compresses to follow a wall that is out of plumb — pick a bulb about equal to the widest point of the gap. Install dry, top down.
Finned U-Channel Shower Glass Seal, 1/4 in Glass, 72 in
- Glass
- 1/4″
- Gap
- 0–3/16″
- Length
- 72″
- Material
- Clear PVC
- Mount
- press-on
- Trim
- Cut to size
Caps and protects the glass edge; the short fin seals even gaps up to about 3/16 in. For wider or tapering gaps step up to a bulb seal.
Finned U-Channel Shower Glass Seal, 5/16 in Glass, 72 in
- Glass
- 5/16″
- Gap
- 0–3/16″
- Length
- 72″
- Material
- Clear PVC
- Mount
- press-on
- Trim
- Cut to size
Caps and protects the glass edge; the short fin seals even gaps up to about 3/16 in. For wider or tapering gaps step up to a bulb seal.
Finned U-Channel Shower Glass Seal, 3/8 in Glass, 72 in
- Glass
- 3/8″
- Gap
- 0–3/16″
- Length
- 72″
- Material
- Clear PVC
- Mount
- press-on
- Trim
- Cut to size
Caps and protects the glass edge; the short fin seals even gaps up to about 3/16 in. For wider or tapering gaps step up to a bulb seal.
Common buying mistakes
- Buying a bottom sweep for a side leak because it was the first result — vertical edges need vertical profiles.
- Replacing one half of a magnetic seal pair; old and new magnet strips repel or misalign.
- Sealing the hinge side so tightly the door cannot swing — hinge-side seals must flex through the pivot arc.
Frequently asked questions
What seal goes on the hinge side of a frameless shower door?
A flexible flap-style side seal or a bulb seal that presses onto the glass edge and compresses against the wall or fixed panel while still allowing the door to pivot.
Why does water leak where my shower door closes?
The strike gap between the closing edge and the wall or panel has opened up, or the magnetic/flap seal there has worn. Replace the pair (both halves for magnets) sized to your glass thickness.
Can I just run silicone caulk down the side gap?
Only on a fixed panel edge. Never caulk a swinging door edge — use a flexible seal so the door still opens.