What Most Homeowners Get Wrong When Buying a Prehung Exterior Door
- Rough opening size and door slab size are not the same thing. Measure the rough opening.
- Swing direction matters more than most people expect. Get it wrong and the door opens into furniture or a wall.
- Exterior doors need to match your wall thickness. A mismatch means trim that will not sit flat and a frame that will not seal.
- Wood, fiberglass, and steel each perform differently in Georgia’s heat and humidity. The right material depends on your situation.
Buying a prehung exterior door is not a weekend decision. Treating it like one is how homeowners end up with a $1,500 mistake framed into their wall.
We see this a lot. A homeowner measures the old door, finds something close, and orders it. Then they spend the next three weekends figuring out why nothing lines up. The door is not the hard part. Getting every detail right before you order is the hard part.
Here is what to know before you spend the money.
Mistake #1: Measuring the Wrong Thing
Most homeowners measure the door slab. That is the door itself. But what they need is the rough opening size.
The rough opening is the framed hole in the wall. The prehung unit, which includes the door, the frame, and all hardware, has to fit inside it. If you measure the old slab and order a unit that same size, the frame may not fit. It may also leave too much gap to work with.
Measure the rough opening width and height. If the old door is still in place, pull off the interior casing to reach the actual framing. Do not estimate. Do not go by what the builder said. Measure it yourself.
Worth thinking about before you order, not after.
Mistake #2: Getting the Swing Direction Wrong
Stand outside and face the door. Hinges on the left, door swings into the house. That is a left-hand inswing. Hinges on the right, that is a right-hand inswing. An outswing door swings toward you.
Get it wrong and the door opens into a staircase, blocks a light switch, or swings into a wall. None of those are quick fixes once the unit is in.
Sketch it out before you place the order. Draw where the hinges are, which way the door swings, and what is behind it. If you are not sure, bring your measurements in and we will talk it through.
Mistake #3: Ignoring Wall Thickness
Prehung exterior doors come with frames built for a set wall thickness. Walls with 2×4 framing need a frame depth of about 4-9/16 inches. Walls with 2×6 framing need closer to 6-9/16 inches.
If the depth does not match your wall, the casing will not sit flush. The door will not seal the way it should.
Older homes in Atlanta and the surrounding area often have walls that do not match current standard depths. If your home has had additions or renovations, measure your wall thickness before you assume anything.
Mistake #4: Picking the Wrong Material for This Climate
Georgia is humid. Summers are long and hot. That matters.
Wood looks great. It also moves with moisture. Without the right finish and regular upkeep, it can swell, stick, or warp. It is a fine choice if you are willing to maintain it.
Fiberglass handles humidity well. It does not swell or rot. It insulates well and can look like wood grain. For most Georgia homeowners, it is a practical middle ground. Brands like Therma-Tru and Plastpro offer fiberglass options built to handle the heat and humidity common across the Southeast.
Steel is strong and secure. It can dent, and if the finish gets damaged and is left alone, it can rust. It is a solid pick for security and budget, but it still needs some care.
No wrong answer. Just know what you are getting into before you decide. Cofer Brothers carries exterior doors in all three materials, and we can walk you through the differences based on your specific situation.
Mistake #5: Overlooking the Rough Opening Condition
You can order the right door and still end up with a bad install if the rough opening has problems.
Check the framing for rot, soft spots, or shifting. In older Atlanta-area homes, clay soil is common. Settling happens. An opening that was straight and square when the house was built may not be now.
If the opening is not plumb, level, and square, the door will not work right. It may not latch. It may drag. It may let in air and water. Fix the opening before the door goes in.
Mistake #6: Not Knowing What Is Included
A prehung unit typically comes with the door slab, the frame, and weatherstripping. What it usually does not include: locksets, deadbolts, and exterior trim such as brick mold or casing.
Know what is in the unit before install day so you are not short on materials. Also ask whether the unit comes pre-primed or pre-finished. Bare wood going into a Georgia summer without a proper finish coat is asking for trouble.
For hardware to go with your new door, the Door and Window Hardware page at the National Association of Home Builders is a reasonable starting point for understanding what options are out there.
One More Thing
The difference between getting it right and getting it wrong usually comes down to a few measurements and a few questions. Ask them before the order is placed, not after.
We have been doing this since 1919. If you have measurements and questions, bring them in. We will look at what you have and help you figure out what you need.
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Frequently Asked Questions
What size prehung exterior door do I need for a standard front door opening?
The most common size is 36 inches wide by 80 inches tall. But standard varies. Measure your actual rough opening. Do not assume the old door was the right size. A previous owner may have installed something that was never a perfect fit.
Can I install a prehung exterior door myself?
It depends on your skill level and the condition of your opening. If the rough opening is solid, plumb, and square, an experienced DIYer can handle it. If the opening needs work or you are dealing with a load-bearing wall, bring in a contractor. A bad install causes problems for years.
What is the difference between an inswing and an outswing exterior door?
An inswing opens toward the inside of the house. An outswing opens toward the outside. Most front doors in the U.S. are inswing. Both work well. Just make sure your choice works with the space behind the door.
How do I know if my wall is 2×4 or 2×6 framing?
Pull off an outlet cover on an exterior wall and check the depth of the electrical box. A shallow box usually means 2×4 framing. A deeper box suggests 2×6. You can also measure the jamb depth on an existing exterior door.
Do exterior doors come with weatherstripping already installed?
Most prehung units include weatherstripping as part of the frame. Quality varies, and it wears down over time. Ask what is included when you shop. In Georgia's climate, a tight seal matters. It affects comfort and energy bills all year long.