How Much Does It Cost to Convert a Window to a French Glass Door?

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Glass half full? More like half full of glass! Modern homes are trending toward open, airy rooms and living areas, so the more glass surfaces and window square footage you can fit into a space, the better. For many homeowners that means enlarging existing window openings. This could be achieved by converting two side-by-side single hung windows into one large picture window, for instance, or turning a side exit into a wide sliding glass door. There’s also another option you might not have considered yet—converting an existing window into a French glass door.

Luxurious and functional, French glass doors are the perfect way to add light and beautiful views in your home, while also gaining additional access to the outdoors. They’re the perfect accent for a back or side exit that leads out to a patio, porch, garden or other eye-catching outdoor space.

But converting a window to a French glass door doesn’t come without its price. It means extending your window’s existing rough openings, which is considered serious demolition. Your contractor will have to cut into your wall’s sheetrock and the home’s siding—and they may even need to rewire or install support beams, depending on where the window is located. That doesn’t mean it’s not well within reach for most homeowners, just that there a couple of factors to consider. Here’s what influences the final total.

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What You’ll Spend on Labor

When you’re trying to ballpark project costs, speak with three to five contractors and ask them each for an estimate. This will be the most accurate way to get a realistic quote. The cost to install French doors starts at about $400, and with labor estimates running between $75 and $180 per door, you can expect an average cost of $525 and up.

Factors that Influence Your French Door Installation Cost

Keep in mind that the $525 figure may vary depending on your area and the scope of your project. In fact, there are several things that may increase the total:

  • Materials. The type of door you choose has a huge impact on the final cost. A mass produced door might cost anywhere from $400 to $2000, depending on the quality, whereas a custom specialty door could easily fetch up to $8000 or more. The frame and type of glass all play into it—expect to spend more for high end materials like mahogany, or glass features like insulation and low-E glazing.
  • Wiring. If the wall beneath the window has outlets or wiring, your contractor will need to engage an electrician to reroute them, which will add to your labor costs. To keep the project simpler overall, it’s best to avoid walls with wiring when you’re looking to add an exterior door, if you can get away with it. Many building codes also require an exterior light on all home exits, with two light switches installed on the wall next to the door. In this case, you may need to hire an electrician anyway to do that part of the job.
  • Roof Overhangs. If your roof overhangs are narrow in the spot over your future door, your door installation may turn into a roofing project, too! Many roofs have slim, two-foot overhangs on exit-free walls. That offers plenty of protection for a window, but it won’t be wide enough to keep your doors in good shape. So you may need to extend the roof overhang as part of the project—or at the very least, purchase an awning to sit over the door. Expect to spend about $100 to $500 for a basic awning, or $900 to $3,000 for a motorized version.
  • Stairs, Stoops, Decks, and Patios. Most home exits sit up and away from the ground to prevent flooding. That means that, in addition to adding your door, you’ll need to build steps or at least a stoop leading out to the ground. You may even choose to add a full-blown deck or patio beneath the exit. Installing brick steps below the door could cost between $800 to $1,500 for a 25-foot by 4-foot-long walkway. A deck costs between $15 and $35, depending on the type of boards you use. Redwood is the cheapest, with low-end lumber costing an average of $5 per board. Composite decking tops the charts as the most expensive material—it costs around $20 to $30 per board.
  • Molding and Trim. The door will need both molding on the interiors and trim on the exteriors, both of which add to materials and labor costs. This is a project you could choose to DIY, particularly the interior trim. A door trimming kit costs between $150 and $300.

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Again, a contractor is your best resource for an accurate estimate. He or she can talk you through the ins and outs of French door installation, finding the best solution for your particular situation and needs. But don’t let the details get you frazzled. A French glass door offers some serious benefits, both in increased property values and aesthetics, so it’s well worth the effort it takes to install!

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