The bottom track should sit on the flat, level part of the tub ledge, set back just far enough that the panels hang plumb and the seal contacts the tub edge evenly. The track must not overhang the rim or sit so far back that the seal misses the edge. The controlling checks are ledge width, level, and the track's stated mounting footprint. The full installation planning framework is in theĀ complete installation guide.
The track position also sets the panel's visual line. A panel that hangs plumb sits parallel to the wall, while a track pushed out at the bottom makes the panel lean away from the wall at the lower edge. The plumb check is done with a level against the glass before the track is fixed, because the lean is hard to see until the door is in use.
Where the Bottom Track Belongs on the Ledge
The track position is set by the door geometry: the panels hang from the top rail, so the bottom track must sit where the panels land plumb. Place the track on the flat part of the ledge, with the seal contacting the tub edge, and keep the track's weep or drainage points clear of the rim.
The plumb line is the reference. A track set too far out makes the panel lean away from the wall at the bottom, and a track set too far back makes the panel lean into the shower; both show up as a seal gap at one side. Mark the plumb line from the top rail before deciding the track position, and set the track so the panel hangs straight along it.
The sealant plan follows the track position: the track is sealed at the ends and along the mounting edge, but the weep holes stay open. Sealing the track as one continuous bead traps water inside, and the trapped water is what the weep holes exist to drain. The sealant is applied around the holes, not over them.
The weep holes define the drainage side, and they are not optional. Water trapped in the track has one way out, and a track whose weep holes sit over the floor instead of the tub drains onto the bathroom floor. The drawing shows the weep side, and the position follows it.
The product drawing answers the position question before any measuring begins: it shows the track footprint, the seal reach, and the weep hole locations for the exact model. Different models of the same style can place the track differently, so the drawing for the model being ordered is the reference, not the drawing of a similar door seen online.
Ledge Positions and Their Best Uses
- Set back from the outer edge: keeps the seal on the tub edge and protects the track from splash; the most common position.
- Centered on a wide ledge: suits wide ledges where the seal reaches the edge without the track hanging over.
- At the outer edge: only when the product drawing shows that position; overhanging risks instability.
Follow the product drawing rather than choosing a position by look. The drawing shows where the weep holes sit and how far the seal extends, and both are fixed by the track's design.
The water test at install is the final position check: pour water along the track with the panels closed and watch where it drains. Water that returns to the tub through the weep holes confirms the position, and water that runs to the floor points to a position or drainage error to correct before the sealant cures.
The ledge width check includes the seal's sweep, not just the track. A ledge that fits the track but leaves the sweep hanging over the outer edge lets water run past the seal, and a ledge that fits the sweep but not the track is equally wrong. Both footprints are measured together.
The seal reach is measured from the track edge to the seal tip, and it must cover the distance from the track position to the tub edge with a small margin. A seal that just touches at the resting position can lift at the ends of travel, so the reach check includes a slight margin rather than a bare touch.
Measurements and Compatibility Factors to Check
- Ledge width and the track's mounting footprint.
- Ledge level along the full track run.
- The seal's reach from the track to the tub edge.
- Clearance for weep holes and drainage at the rim.
- The plumb line from the top rail to the ledge.
Measure these before mounting; the track cannot be moved after the holes are drilled. The ledge width is measured at the flat mounting surface, not at the decorative edge, because the track sits on the flat part.
The track is leveled in both directions before the position is final: along its length for the panels to travel, and across the width for the seal to sit evenly. A track level along its length but tilted across the width makes the seal contact at one edge only, and the leak appears at the high side.
The first-shower test is the real proof of the position. Run water along the track with the panels closed and watch where it collects: water that pools at the outer edge means the track sits too far out or the weep holes are blocked, and water that runs under the seal means the track sits too far back. Adjust before the final sealant is applied.
Position, Seal and Drainage Tradeoffs
Set the track too far back and the seal may miss the tub edge, letting water escape along the rim; set it too far out and the track overhangs, looks unstable, and can block water from draining back into the tub. The right position balances seal contact with drainage, and the product drawing defines where that balance sits.
The tradeoff is often visible in the first shower: a track set for maximum seal reach can trap water at the outer edge, while a track set for drainage can leave the seal short of the rim. Both are corrected at install time by following the drawing and testing with water before the door is sealed permanently.
Drilling is the point of no return for the track position, so the position is confirmed twice before any hole is made: once from the product drawing and once from the plumb line. A track mounted one hole too far out cannot be moved without patching the tile, and the patch becomes a permanent mark on the ledge.
Common Track Placement Mistakes
- Centering the track on the ledge without checking the seal's reach.
- Letting the track overhang the outer edge.
- Blocking the weep holes with sealant or debris.
- Drilling before confirming the panels hang plumb from the top rail.
- Sealing the track in place before testing the water flow.
Final Checks Before Installation
- Confirm the ledge is wide enough and level for the track.
- Mark the track position from the product drawing, not by eye.
- Check the seal contacts the tub edge along the full run.
- Keep the weep and drainage points clear.
- Test with water before the final sealant is applied.
The track position is part of the wider installation plan, covered in theĀ complete installation guide.
The plumb line from the top rail is the reference the track position follows, and it is checked before any drilling. A track set to the ledge but off the plumb line makes the panels bind at the bottom and the seals gap at the top, so the two lines are reconciled before the position is marked.
Frequently Asked Questions
Should the bottom track touch the tub edge?
The seal should contact the tub edge; the track itself usually sits slightly back. Confirm the position from the product drawing so the seal reaches the edge without the track overhanging.
What if the ledge is not wide enough for the track?
The door will not mount correctly. A narrow ledge cannot seat the track and seal, so measure the footprint before ordering and choose a model that fits the ledge.
Do bottom tracks need weep holes?
Many do, to let water trapped in the track drain back into the tub. Keep them clear and positioned over the tub side, not blocked by sealant.
Can the track be shimmed to level a sloped ledge?
Small slopes can be corrected within the door's adjustment range. Larger slopes need the ledge addressed first, because the track must sit level for the panels to travel.
Why does the seal gap at one end after installation?
Usually the track is not level or the panel is not plumb. Check the level along the track and the plumb of the panel at both ends before adjusting the stops or the seal.
Set the track from the product drawing, check the seal and drainage, then drill.Ā Shop Bathtub Sliding Shower DoorsĀ and verify the track footprint against your ledge.