A service call where the usual fixes did not apply: the sliding panel’s frame had separated from the glass, and the gasket was no longer sealing. How we found it, what the repair options are, and why the original order information matters before anyone quotes.
In short: A homeowner called us about an Andersen sliding patio door that was letting in a strong draft. The usual suspects, the weatherstrip, the lock, the rollers, were fine. The problem was in the sliding panel itself: the frame had separated from the glass, and the gasket that is supposed to seal glass to frame was no longer tight, so cold air in winter and hot air in summer come straight through the edge of the glazing. If your sliding door is drafty, call us for an inspection, and have the original order information ready: the dealer, the date, and the unit label. It decides what can be done under warranty and which parts fit.
“The door is closed and locked and I can feel the cold.” That is how most draft calls start, and most of the time the fix is small: a worn weatherstrip, a lock that no longer pulls the panel tight, rollers that have dropped so the panel sits crooked in the frame. We went expecting one of those. The door is an Andersen sliding patio door, a few years old, in a private house, and it looked fine from across the room.
Up close it was not. Running a hand along the edge of the sliding panel, the air was not coming from the meeting stile or the sill. It was coming from the glass.
A sliding door panel is a frame wrapped around an insulated glass unit. The glass sits in a pocket in the frame, held by glazing beads or a glazing leg, and sealed to the frame by a continuous gasket or glazing tape. That seal is the only thing between outside air and the room along the whole perimeter of the glass, and it only works while the frame holds the glass tight.
On this door the frame had pulled away from the glass along the stile: you can see the gap in the photograph, looking down the edge of the panel toward the sill. With the frame no longer pressed against the glass, the gasket has nothing to seal against. Air passes between glass and frame the full height of the panel. It is a draft you can feel with your hand, and in a heating season it is a draft you can see on the bill. The panel also loses some of its stiffness, because a glazed panel relies on the glass to brace the frame, and that can make the door harder to slide and lock, which is often the second complaint.
Why it happens varies: a panel that was not fully seated when the door was assembled, a corner joint that has opened, a glazing bead that has released, a door that has been forced or racked, or simply heat, sun and years of sliding. It does not matter for the diagnosis; it matters a great deal for the fix.
This is the part homeowners do not expect. A branded patio door is not one product; it is a model, a series, a size, a glass make-up and a hardware package, made to an order, and the parts that go back into it have to match that order. Before we can tell you whether the panel can be re-seated and re-glazed, whether a new sash or glass unit is the right repair, or whether any of it is covered by the manufacturer’s warranty, we need to know exactly what the door is. So when you call, have ready:
With that we can check the warranty position with the manufacturer, order the correct parts, and give you a real answer instead of a guess. Without it, the only honest options are a generic repair or a new panel measured on site, which may be the right answer anyway, but you should know what you are choosing.
In every case the weatherstrip, the rollers and the lock are checked while the panel is out, because a door that has been drafty for a while has usually been slammed and forced for a while too.
Do not caulk the glass to the frame; it hides the problem and makes the proper repair harder. Call us at 929-235-1233 or send photos of the door and the label, and we will schedule an inspection. We supply and install Andersen, Pella and Marvin doors and repair all three, and the inspection tells you what you have before anyone talks about replacing it. For other glass and door problems see our maintenance services and repair pages.
Usually a worn weatherstrip, a lock that no longer pulls the panel tight, or dropped rollers. Less often, and harder to see, the panel frame has separated from the glass so air passes between glass and frame along the whole edge. An inspection tells which.
Often yes: the panel is removed, the glass re-set in the frame with new glazing tape or gasket, and the beads refitted. If the frame corners have failed or the glass unit has lost its seal, a new panel or glass unit is the repair.
It depends on the series, the age of the door and the cause, which is why we ask for the original order information and the unit label before we answer. We check with the manufacturer on your behalf.
The order or invoice with the date, a photo of the unit label on the frame or spacer, the glass stamp if there is one, and who installed the door.
No. Caulk hides the separation, traps water in the glazing pocket and makes the proper repair harder. Have the panel inspected and re-glazed instead.
Yes. We inspect and repair Andersen, Pella, Marvin and other branded patio doors across New York City, Long Island and New Jersey, whether or not we supplied them.
Andersen windows and doors Sliding doors Patio doors Insulated glass units Maintenance services Storefront glass service call Request an inspection
About this page. Written by Alex GC Inc. d/b/a Alex Glass Construction and reviewed before publication by Aleksandr Chernovolenko, Managing Partner, with our design and estimating lead and a field foreman. Our foremen hold the NYC DOB Site Safety Training supervisor card and our crews the 40-hour worker card; we are certified to fabricate, install and service Alutech and Everest aluminum systems. Facts are drawn from our own projects, manufacturer test data and the applicable codes; where we are giving an opinion, we say so. Last reviewed September 2026. Credentials
Send photos of the door and its label, with the original order information if you have it. We will inspect it and tell you whether it is a re-glaze, a new glass unit or a new panel, and whether the warranty applies.
