How to Guide

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How to Measure for an Exterior Prehung Door

A pre-hung door is a door that is already hanging in its own frame. It's an all-in-one

package that ensures the smoothest possible installation of your door.

We recommend a prehung door if your situation is one of the following:

1. No existing door frame

2. The existing door frame is damaged

3. New construction

Note:

When installing an exterior door, unless you are a pro, it's extremely hard to tight-fit an

exterior slab door.

· Prehung doors come with weather-stripping and are tight-fitting off the shelf.

· A tight-fit door will save you on your energy bill.

What to consider when buying a pre-hung door?

· Make sure the new door frame will fit the rough opening. We recommend a rough

opening that is slightly larger than the outside unit dimension of the new prehung

door. This allows for shimming to level the unit.

· Jamb width refers to the thickness of the wall. The jamb needs to cover the stud

plus any wall application such as dry wall or sidings.

· Know your door handing (swing). Stand with your back against the hinge-side of

the frame and extend an arm in the direction you wish the door to open. If you

extended the left arm, then you need to order a LEFT-HANDED door. If you

extended the right arm, then you need to order a RIGHT-HANDED door.

· Though exterior doors typically swing inward, outswinging exterior doors are

available. So be sure to add "inswing" or "outswing" to your notes before

ordering.

Door size. Measure the width and height of your old door. Round these up to full inches

to find the size of the replacement door you’ll need. If, for example, your door measures

35-3/4 in. wide and 79-1/2 in. tall, you’ll order a 36 in. by 80 in. door. For double doors

this will be the total of both doors. For example, two 36 in. by 80 in. doors equal one 60

in. by 80 in. door size. Similarly, for a single door with sidelite(s), the width of the

sidelite(s) will need to be added to the door width.

PAGE 1
How to Measure for an Exterior Prehung Door A pre-hung door is a door that is already hanging in its own frame. It's an all-in-one package that ensures the smoothest possible installation of your door. We recommend a prehung door if your situation is one of the following: 1. No existing door frame 2. The existing door frame is damaged 3. New construction Note: When installing an exterior door, unless you are a pro, it's extremely hard to tight-fit an exterior slab door.
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Jamb (Frame) width. Measure from the backside of the interior trim to the backside of the exterior trim (Figure A). Specify this jamb width when you order your new prehung door. This guarantees that the interior trim will fit flush to the wall without adding “jamb extensions.” Rough opening. You’ll have to remove the interior trim to get accurate measurements of the rough opening. Measure the opening width between framing members and from the bottom of the sill to the top of the opening.
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Single Door Frame (Unit) Dimension: Width: Add 1-1/2 in. to the width of the actual door Height: Add 1-3/4 in. to the height of the actual door *For outswing unit height, add 1 in. to the height of the actual door Rough Opening: Width: Add 2-1/2" to the width of the actual door Height: Add 2-1/4" to the height of the actual door *For outswing rough opening height, add 1-1/2 in.