Bert spent 25 years working as a home-improvement and residential construction contractor in central Florida.

This sliding glass door needs a lot of love. A repair cap will help it coast smoothly across the frame.

Many homeowners find that after years of daily use, their sliding glass door no longer glides the way it once did. Instead, it bounces up and down every time someone opens or closes it.

When this happens, a close inspection of the door frame's bottom track reveals compressed areas in the glide rail where the rollers skip. Continuing to use a set of worn out or dirty rollers can, in extreme cases, deform the door's soft aluminum guide rail to the point where the bottom of the door drags.

When addressed quickly enough, covering a damaged glide rail with a stainless steel track cap solves the sliding door's bouncing problem. Because the track cap gives the door's rollers a new flat surface to ride on, the glass door slides smoothly when opened and closed.

This extremely damaged door frame required a wire brush to remove stubborn debris.

Remove the glass doors from the frame to access the glide track. Open the outside sliding door about half way, lift straight up and tilt the bottom toward yourself until the lower end swings free of the track. Set the door safely aside. Repeat this procedure on the inside door. Clean and inspect the door rollers while the door is off the frame. Both wheels should spin freely. If not, they either need maintenance or replacement.

Clean the glide track with a stiff bristle brush. Work the bristles aggressively along the entire track to remove all buildup. In extreme cases, such as the door in the image, consider using a drill-equipped wire wheel. This aggressive tool quickly removes stubborn buildup.

Vacuum up the debris and inspect the glide track for low mushroom-shaped sections. A visual inspection of the top of these misshapen areas show why the glass door jumps up and down as it rolls across the track. Notice how the areas without a mushroom shaped track do not have low spots and the rollers coast smoothly. Correct a moderately misshaped glide track with a sanding stone. The purpose here is to narrow the wide spots enough for the repair track to snap over the mushroom-shaped sections without deforming the repair track's finished shape. As always, wear all PPE including safety goggles and work gloves. Clean the entire workspace when complete.

The length of the repair cap should match the slide glass door frame's glide rail.

Measure the door frame's glide rail. Extend a tape measure across the doorway and measure the length of the glide rail. Pay attention to any drainage spaces at the ends of the glide rail. The repair cap must not extend past the glide rail and fill these small gaps. Transfer the measurement to the repair cap. Double check the measurements of both the rail and the cap.

Set the repair cap on a solid surface with the open end facing down. Cut the cap with a rotary tool equipped with a metal-cutting disc or a hacksaw. Flip the cap over and inspect the edges for straightness. Use pliers to remove any burs from the cut end and straighten out any misshaped sections.

The curved ends of this stainless-steel track repair cap snap onto the existing track's glide rail.

Apply a small amount of adhesive along the length of the repair cap. Adhesive plays two important roles when repairing a sliding door track: it locks the repair cap in place and it fills the space between the low spots on the glide rail and the inside of the repair cap. Without a filler the heavy glass door would deform the new rail cap until it matched the shape of the original. The type of adhesive required depends on the amount of damage to the glide rail. Silicone works well for doors with lightly damaged rails, while badly damaged rails sometimes require epoxy.

Start one end of the repair cap onto the old track and work toward the opposite end.

Hold one end of the repair cap against one end of the glide rail. Apply pressure to the end of the cap until it snaps onto the rail. Expect to notice a small amount of adhesive expel from the channel. Once the repair cap starts, lock it in place with a block of wood and a rubber mallet. Set the wood onto the cap and strike the wood with the mallet until the repair cap snaps into place. Continue to install the repair cap across the door track using the same method. Avoid overworking an area. Clean up excess adhesive using the appropriate methods. Do not let the waste adhesive dry on the door frame.

Use a rubber mallet to snap the repair cap onto the sliding door frame.

Clean the sliding door's rollers with a stiff bristle brush. Really work the bristles into the slot to reach all the hair and other debris that worked deep inside. Spin each roller with a finger to verify smooth operation. Lubricate the rollers with a silicone-based spray lubricant. Petroleum-based lubricates work temporarily, however, they tend to collect the dirt and debris that contributes to premature wear.

Hold the door upright. Angle the top towards the appropriate groove in the upper door frame. Light the door up into this groove and simultaneously position the bottom of the door onto the repaired sliding door glide track. Test the door.

A sliding glass door will operate smoothly for many years with a little love and care. Most of the time cleaning debris from the track is all the maintenance sliding door rollers need. Applying a little lubricant to the rollers once or twice a year prolongs the life of the rollers considerably.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.