Patio door replacement, starting with the opening

What is patio door replacement?

Patio door replacement is swapping the large glazed door between a living space and a deck, patio or garden. Two decisions set the price. The first is configuration - sliding, hinged French, multi-slide or bi-fold. The second, and the bigger one, is whether the new unit is a retrofit into the existing frame or a full-frame replacement that takes the wall back to the framing. Most jobs are same-size retrofits, and most quote disputes are about which of the two you are getting.

Signs you need patio door replacement

• Condensation or a permanent haze between the panes - the insulating glass unit has lost its seal and the panel is the item that needs replacing
• The door is hard to move even after the track has been cleaned and the rollers adjusted
• You can feel moving air at the interlock where the two panels meet, with the door fully closed and locked
• Water is reaching the floor inside the track after driving rain, which means the sill drainage is blocked or the pan has failed
• You are reworking the room - a kitchen extension, a deck rebuild, a wider opening - and the door is part of the design rather than a repair

Seeing something not on this list? Browse doors problems by symptom →

How patio door replacement actually works

1. 1

   Deciding what the opening will actually take

   The installer measures the existing frame, the rough opening behind it, and the header above it. A same-size retrofit works within the existing structure. Anything wider, or a switch from a two-panel slider to a three- or four-panel unit, means the header and the stud pack either side get rebuilt.

   Watch forA wider door quoted without any mention of a header. Widening a load-bearing opening is structural work, sometimes permitted work, and it is not an upgrade line item.

2. 2

   Configuration - sliding, French, multi-slide or bi-fold

   Judge it on floor space and traffic before aesthetics. A sliding panel needs zero clearance. A French pair swings, and needs a couple of feet of clear floor on whichever side it opens toward. Multi-slide and bi-fold open most of the wall but stack panels somewhere, and both are meaningfully more expensive per foot.

   Watch forA French pair specified into a room where the swing lands on a dining chair or a sofa back. Measure the swing arc on the floor with tape before signing.

3. 3

   Frame material for your climate

   Vinyl is the value default and is dimensionally stable. Fiberglass moves least with temperature and holds large panels well. Clad wood suits interiors where the inside face matters. Bare aluminium conducts and is the reason old patio doors sweat.

   Watch forLarge sliding panels in a frame that is not rated for that span. Oversized glass in an under-specified frame is where sagging and roller failure begin.

4. 4

   The glass package, chosen by which way the door faces

   A west-facing patio door takes hours of low-angle afternoon sun and is a different specification from a north-facing one - usually a low-E coating tuned to reject solar heat rather than one tuned to retain it. Tempered glass is standard on doors; laminated adds security and sound.

   Watch forOne glass package quoted for every opening in the house. It is the easiest specification to get right and the most commonly copied and pasted.

5. 5

   Removal, sill pan and drainage

   The old unit comes out, the sill is inspected, and a pan is fitted so any water reaching the track is drained back outside. Patio doors sit at the wettest point of most walls - the sill detail matters more here than on any other door in the house.

   Watch forWeep holes blocked by sealant. Somebody caulking the outside of the sill "to stop leaks" traps water inside the track, which is the exact opposite of how the door is designed to work.

6. 6

   Setting, squaring and locking

   The unit is set plumb and level, shimmed at the jamb and under the sill so it does not deflect, fastened, and the panels are adjusted until the interlock closes evenly along its full height. The lock and any secondary foot bolt are then set.

   Watch forA door that locks only if you lean on it. That is an out-of-square installation, not a lock adjustment, and it will only get worse.

What does patio door replacement cost?

Patio door replacement commonly runs $1,200 to $8,000 installed. A same-size vinyl slider retrofit sits near the bottom; a wide multi-slide or bi-fold in a rebuilt opening sits at the top, with the framing work rather than the door driving the difference.

See the full patio door replacement cost guide - by material, size and region →

If the number is the problem, here are the ways people pay for it →

Door size estimator → Check what your opening will take.