A sliding door should close smoothly and seal tightly. If you’ve had a door installed recently and it still leaves a gap, the problem usually comes down to installation errors.

Even high-quality doors will underperform if they’re not fitted correctly.

Here are the most common installation mistakes that cause gaps in sliding doors — and how to fix them.

Panel Installed the Wrong Way Around

Sliding door panels are designed with a specific inside and outside orientation.

If the panel is installed back-to-front, the seals won’t meet correctly and a gap will remain when closed. In some cases, the installer may still be able to fit the panel into the frame, but it won’t operate or seal properly.​

Solution:
Remove the panel and reinstall it in the correct orientation so the seals engage properly.

Floor Not Levelled Before Installation

If the subfloor or sill wasn’t level before the door was installed, the track will sit unevenly.

This causes one side of the door to close while the other side remains slightly open, creating a visible gap.

Solution:
Remove the sliding door, level the floor, and reinstall the track and panel for a perfect seal.

Dirt or Debris in the Track