A sliding door needs no interior floor space and gives you half the opening. A French door needs about thirty inches of swing clearance per panel and gives you nearly the full opening, with generally better air sealing. Sliders cost $2,000 to $5,500, French doors $2,500 to $6,500.
Both fit a standard patio rough opening, so the choice is rarely about construction. It is about floor space, how wide you need the opening to be, and how much you care about air sealing.
Here is the comparison and the specific questions to answer before choosing.
Side by side
| Sliding patio door | French door | |
|---|---|---|
| Installed cost | $2,000 to $5,500 | $2,500 to $6,500 |
| Interior floor space needed | None | About 30 inches per panel |
| Clear opening width | Half the unit | Nearly the full unit |
| Air sealing method | Interlock and brush weatherstrip | Compression gasket |
| Typical air leakage | Higher | Lower |
| Snow on a deck | Unaffected | Can block an outswing pair |
| Screen | Sliding screen on the track | Retractable, or none |
| Moving furniture through | Constrained to half width | Full width available |
| Maintenance items | Rollers, track | Hinges, astragal alignment |
| Look | Contemporary, minimal | Traditional, substantial |
Choose a slider when
- Interior floor space is tight, which is the most common deciding factor.
- Furniture sits close to the opening and a swinging panel would conflict.
- The deck outside is small and an outswing pair would have nowhere to go.
- The architecture is contemporary or mid-century, where the minimal profile suits it.
- Budget matters, since sliders generally cost less.
- You want an exterior screen that stays permanently in place.
Choose a French door when
- You want the full opening for moving furniture or for entertaining.
- Air sealing is the priority, since compression seals outperform sliding interlocks.
- The house is traditional and a slider would look wrong on the elevation.
- You are replacing a failed slider and have the interior floor space available.
- You want an inactive panel that stays closed most of the time and opens when needed.
- You dislike the maintenance cycle of patio door rollers and tracks.
The floor space test
Before choosing a French door, do this. Measure thirty inches out from the wall at the opening and mark it on the floor with tape, across the full width of the opening. Then live with that tape for a few days. That is the area that must stay clear for an inswing pair to open fully, and it is a genuinely significant piece of a room. If a sofa, a dining table or a traffic path falls inside it, you have your answer. Outswing is the alternative, but on a deck in a snow climate an outswing pair can be blocked by drifted snow exactly when you most want the door to work, so it is not a free solution.
Ranges reflect typical Capital Region projects and are for planning only. Every Sundog quote is written, itemized, and free.
Frequently asked questions
Which is better, a sliding door or a French door?
Neither in the abstract. French doors seal better and open wider. Sliders need no floor space and cost less. The deciding factor for most Capital Region homes is whether you have thirty inches of clear floor in front of each panel for an inswing French pair.
Do French doors leak more air than sliders?
Generally less. French doors seal by compression, meaning the weatherstripping is squeezed when the door latches, the same way an entry door seals. Sliders seal with an interlock and brush weatherstripping that the panel slides past, which cannot be as tight. The exception is a French door in a racked opening, which leaks badly at the astragal.
Can I replace a slider with French doors?
Usually yes, because standard patio rough openings work for both, so the structural work is often minimal. Check interior swing clearance first, and note the threshold height may differ slightly, which matters if you have flooring right up to the door.
Are French doors more expensive?
Somewhat. French doors run $2,500 to $6,500 installed in the Capital Region versus $2,000 to $5,500 for a comparable sliding door. The gap narrows at larger sizes and widens if you add a multipoint lock, which is worth having on a French pair.
What about an outswing French door on a deck?
It solves the interior floor space problem entirely and it generally sheds water better, since wind pressure pushes the door against its stop. The trade in our climate is snow. Drifted snow on a deck can physically block an outswing pair, and you have to shovel before you can open the door. Under a covered porch it is an excellent solution.
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