Demolition: Converting a Window to a Door

Follow these guidelines for removing a window and creating a rough opening.
By: Mark Clement

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So you've just built a new deck on the back of your house and those once-lovely double windows in the living room would now make a better door—sliding glass or French—out to that awesome deck.

The good news about turning a window into a door, assuming it's wide enough, is that the advanced carpentry required for altering a load-bearing wall is pretty much done for you. That doesn't mean the project is easy—my Cuss-O-Meter is tipping out at 5 out of 5—but the gist is that you first remove the window and then remove the building materials beneath the existing window, creating the rough opening for the new door.

Here's how it breaks down:

Siding. Compare the exact height and width of your new door with the height and width of the siding opening. You may have to delete some siding details, and that's easier with some siding than others. For example, removing and replacing wood or concrete siding elements requires a different skill set from what you need for vinyl or stucco. And this will give you an idea of what, if anything, you need to buy ahead of time to repair the siding. With any luck, the door will fit and you can leave the siding intact, but it's vital that if you alter the siding, you replace it using best practices to prevent leaks.

Safety net. Have a few sheets of plywood and some 2-by-4 on hand to cover the opening in your wall in case you get rained out, your wife has your new baby a few weeks early, or the job otherwise takes longer than you thought.

Interior trim. As with the siding, check the door's dimensions against your trim dimensions. It'd be nice if the door snuck in under the trim and you could leave it in place, but I usually find that to be nothing more than wishful thinking.

If you have to strip the trim, do so carefully to keep the drywall as intact as possible. Use a utility knife to cut the caulk bead before cranking the trim off the wall with a hammer and a flat bar.

The base and the shoe molding need to go, too. Cut them back so that they'll meet the new door casing as if both were installed on the same day. I like a Japanese-style pull saw for getting a fine, straight cut here. Lay this out carefully so your trim is sweet when you're through. And be careful of the finished floor when cutting. Note: A reciprocating saw is the wrong tool for this job.

Window parts. If you have to strip the windows out to the original rough opening in the framing (RO), here's a demolition checklist:

  • Modern-ish windows are hung on your house by nails driven through a flange in the window that sits on the exterior side of the house's sheathing. Either expose this flange and pry out the nails or use a reciprocating saw and pummel the flange.

  • If you have replacement windows, they're held by screws driven through their jambs (and probably a ton of caulk). Find and remove the screws and then do what needs to be done to break the caulk seal. You'll probably need a combination of cutting and prying tools. I see a painter's 5-in-1 tool coming in handy here.

  • For older, double-hung windows, remove the sashes, the stops and the parting bead to expose the jamb.

Removing the jamb. Taking a window jamb apart can be a chafe because you never know how the original assemblers put it together. To avoid infuriation in dealing with nails and screws you can't see, remove it my way:

  1. Get a recip saw and a long demo blade. I have a bunch of Milwaukee ax blades in my saw box.

  2. Through-cut across the middle of each jamb leg.

  3. Crank out the bottom half of each jamb leg.

  4. Wrench out the top half of each jamb leg.

  5. Pry the head jamb free.

Removing the lower framing assembly. Cut the siding carefully, using a saw and blade appropriate to the material. This is a finish cut. All I can share with you here is the mantra layout, layout, layout. And once more for luck—layout! Cut the siding plumb (remove the sheathing and the building paper too), and account for the trim details when determining where to cut it.

Getting the drywall that covers the jack studs and the bottom wall plate out is now pretty elementary. Use a recip or drywall saw to cut, and then pry the drywall free. For the framing, use a recip saw to cut through the nails holding everything together. Pluck out the parts using various combinations of nail picks, flat bars, pry bars and good old-fashioned leverage.

You've now successfully cut a hole in your house. It's time to put the demolition tools aside and use best practices and materials for installing a beautiful and leak-free door.

Mark Clement is a remodeler and author of The Carpenter's Notebook and The Kid's Carpenter's Workbook, Fun Family Projects! Find out more at

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