How to Install a Pre-Hung Exterior Door
Learn how to prepare the rough opening, waterproof the subfloor sill, set a pre-hung exterior door, shim the frame for consistent reveals, and securely anchor it.
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🧰 Required Tools & Equipment
- ✓ Cordless drill / driver
- ✓ 4-foot level
- ✓ Caulking gun
- ✓ Hammer
- ✓ Utility knife
- ✓ Tape measure
📦 Materials & Supplies
- ✓ Pre-hung exterior door unit
- ✓ Exterior-grade silicone sealant
- ✓ Composite or cedar door shims
- ✓ 3-inch exterior wood screws
- ✓ 2-1/2 inch exterior trim screws or casing nails
⚠️ Safety Checkpoints & Warnings
- • Use a two-person lift or proper lifting mechanics when maneuvering heavy insulated or solid-core doors.
- • Wear safety glasses when cutting shims, driving fasteners, and drilling into framing.
- • Verify no hidden electrical wiring runs behind the king studs before driving 3-inch anchor screws.
📋 Step-by-Step Guide (6 Steps)
Check the Rough Opening for Plumb and Level
Place a 4-foot level across the bottom subfloor sill to ensure it is dead level. Check both side king studs with the level to identify any bows, twists, or out-of-plumb conditions. Measure diagonally from corner to corner across the opening to verify the frame is square.
- • Spirit level bubble perfectly centered across the bottom sill.
- • Both diagonal corner-to-corner measurements match within 1/8 inch.
- • Failing to check the sill level before setting the door, causing bind issues later.
Apply Sill Sealant Beads
Load exterior-grade silicone caulk into the caulking gun and snip the nozzle to a 3/8-inch opening. Lay two continuous, thick beads of caulk across the entire width of the subfloor sill. Run the beads up 2 inches onto the vertical framing on both bottom corners to prevent water penetration.
- • Two unbroken, wavy beads of silicone running from left jamb stud to right jamb stud on the sill.
- • Caulk running up the inside faces of both corner trimmers.
- • Leaving gaps or dry spots in the caulk lines where wind-driven rain can leak underneath.
Set the Door Unit into the Opening
With the exterior brickmould or flange facing outward, tilt the bottom sill of the door onto the caulked subfloor first. Push the top of the frame firmly into the rough opening until the exterior trim rests flush against the house sheathing. Center the entire door assembly left-to-right within the opening.
- • Door sill resting completely flat into the caulk bed.
- • Exterior casing or brickmould resting flat against the outer wall surface on all sides.
- • Sliding the door along the sill, which smears away the protective caulk beads.
Plumb and Fasten the Hinge Side Jamb
Place the 4-foot level along the inside face of the hinge-side jamb. Insert pairs of opposing shims behind each hinge location between the jamb and the framing stud until the jamb is perfectly plumb in both directions. Drive temporary 2-1/2 inch screws through the jamb and shims directly behind the top and bottom hinges.
- • Level bubble dead-center on the interior and face edges of the hinge jamb.
- • Shims firmly seated behind every hinge without distorting the wood jamb.
- • Over-tightening screws without adequate shims, bowing the hinge jamb outward.
Shim and Fasten the Strike Jamb for Even Reveal
Close the door slab and inspect the margin gap (reveal) between the door edge and the frame on the top and latch sides. Insert shims behind the strike plate and top/bottom of the strike jamb until the reveal is uniform (about 1/8 inch) all around. Fasten the strike jamb through the shims into the framing with 2-1/2 inch screws.
- • Consistent 1/8-inch reveal along the top header and latch-side jamb.
- • Door latches smoothly without rubbing the strike plate or head jamb.
- • Shimming only at the latch plate, creating a bowed frame that rubs at the top or bottom corner.
Anchor Hinges and Trim Excess Shims
Remove one factory short screw from the top and middle hinges on the jamb side. Drive 3-inch exterior wood screws through the empty hinge holes straight into the wall framing studs to permanently prevent door sag. Score protruding shims with a utility knife and snap them off flush with the frame.
- • 3-inch screws seated flush inside the hinge leaves without stripping screw heads.
- • All shims cut flush behind the drywall/framing line with no pieces protruding.
- • Door swings freely and stays in place when opened halfway without swinging closed on its own.
- • Driving the 3-inch screw at an angle, pulling the hinge jamb out of plumb.
Credit: inspired by an original tutorial by The Excellent Laborer — watch the original on YouTube.
Don’t have everything?
- No Composite shims? Cedar or rot-resistant wood shims
- No 4-foot level? 2-foot level placed on a straight 4-foot piece of lumber