Prehung Exterior Doors: What Are They (And How To Install Them)

There's a lot of jargon in the construction industry, and it's common for DIYers to see, hear, and even use terms they don't fully understand. Just like with anything, you learn as you go, increasing your understanding of how to build and construct with each project you take on. When it comes time to work on exterior doors, you may hear the term "prehung" and wonder exactly what it means. Essentially, a prehung door is simply one that is in a frame and already has hinges attached.

You don't need to be an expert in door anatomy to install a prehung door in your home, but having a foundational understanding of door parts helps when you're selecting the right one for your home. When replacing a door, you'll choose between a prehung door, which includes the frame and jamb, and a slab door, which is just the door itself.

For both new construction and renovations, it's more common to purchase a prehung door for an exterior entry. If you're replacing an interior door and your frame is still in good condition, a slab is the more economical choice. However, for DIY installations, the factory-installed frame is the easier option. It has weather stripping and mortises for the handle and lock sets, making installation easier for beginners, so you'll be less likely to need a draft blocker to insulate your doors this winter.

While some DIYers see this project as outside their skill set, the cost of installing a new front door makes it worth considering for others. Installing a prehung door is relatively straightforward, but there are a couple of details you have to get right. The first thing you need to know is the size of your door. Most doors come in standard sizes, so a 36-inch door opening actually measures about 37 7/16 inches wide. Be sure to measure the door opening, frame height, and jamb width before you order your door.

Once you take out the old door, there will be a large hole in your house until you finish the project, so you'll want to ensure a complete installation by the end of the day. Have all tools and materials ready beforehand, and plan on having a second person help. Remove everything, including screen doors, strike plates, and trim from both the inside and outside of the house. Once you have the door frame exposed and the door jamb unscrewed, you can push the door out with your helper's assistance.

After unpacking the new prehung door, dry-fit it to make sure it fits properly. Then, caulk the jamb and use construction adhesive under the threshold before sliding it permanently into place and securing it with screws. Finally, use shims to level and square the door so it opens and closes properly, then reinstall the trim.