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How to Install a Prehung Exterior Door

Modernize your home with a bigger front door! Learn how to install a wider prehung exterior door by cutting the existing rough opening wider and higher to accommodate a larger front entry door.
Print Instructions
measure the width of door rough opening

Supply List

  • New Exterior Door
  • Pressure treated wood (for header and sill if replacing)
  • 2x4's to reframe the door
  • Sawzall
  • Level
  • Hammer
  • Prybar
  • LocTITE insulation foam
  • Cordless drill
  • Nail gun
  • construction screws

Instructions : Step by Step

  • Remove the old door
    man removing old brown raised panel exterior door with 4 square windows at top
  • Measure the rough opening for the new door
    Cut new opening 1" - 1 1/2" higher and wider to leave room for leveling with shims.
    how to measure for a wider front entry door
  • Cut the new rough opening using a sawzall
    cutting a front door rough opening with a sawzall to make the door opening wider
  • Using a hammer and pry bar, remove the old trim, 2x4's and existing frame
    reframing front door rough opening for a new wider door
  • We installed a new header and replaced the rotted sill
    cutting a front door rough opening and door jamp with a sawzall to make the door opening wider
  • Be sure to use pressure treated wood for sill and header
  • Frame new door opening with 2x4's to match existing frame
    *2x4 construction was "code" in our area during the time this house was built.
    frame front entry rough opening nailing 2x4s to wall and joist
  • Add flashing tape around the door
    Flashing tape provides and extra layer of protection from air and water penetration
    add flashing tape around front entry rough opening to prevent air and water penetration
  • Install new door
    1. A prehung door comes completely assembled, including the hinges, frame and exterior trim. Simply add the door to the new opening, level and nail or screw to door frame.
    2. Use wood shims to level the door on the sides, bottom and top if necessary. Be sure to use a level to ensure proper installment
  • Fasten door to frame
    Use a cordless drill and nail gun
    prehung black exterior white interior door with sidelight and white vinyl trim
  • Seal new door with foam insulation
    We used LocTITE foam insulation to seal around the gap between the door and frame to make it weather tight
  • Install interior trim around new door
    white interior front entry door with art deco privacy glass and sidelight
  • Add exterior trim around new door
    Our prehung door included vinyl trim

Tips

Our door was factory finished with black exterior paint with a white interior. You will pay extra for a factory finish but many times it's worth it!
Author: Jessica Bruno
Cost: varies depending on scope of work