From Start to Finish: How to Build a Solid Rough Opening for a 36-Inch Door

From Start to Finish: How to Build a Solid Rough Opening for a 36-Inch Door

Building a solid rough opening for a 36-inch door involves several steps to ensure proper alignment, levelness, and structural integrity. Here’s a step-by-step guide to help you through the process:

Materials and Tools You’ll Need:

  • Measuring tape
  • Level
  • Carpenter’s square
  • Circular saw
  • Reciprocating saw (optional)
  • Pry bar
  • Hammer
  • Nails or screws
  • 2×4 lumber
  • Construction adhesive
  • Shims
  • Door frame kit or casing
  • Safety glasses and gloves

Measure and Plan

  1. Measure the width and height of your 36-inch door slab to verify its exact dimensions.
  2. Determine the rough opening size needed. Typically, you should add 2 inches to the width and 2-1/2 inches to the height of the door slab. So, for a 36-inch door, your rough opening should be 38 inches wide and 82.5 inches high.

Remove Existing Materials (if applicable)

  1. If you are replacing an existing door, remove the old door, frame, and trim using a reciprocating saw, pry bar, and hammer.

Frame the Rough Opening

  1. Measure and mark the top plate of the wall for the height of your rough opening.
  2. Use a circular saw to cut through the drywall and studs along the marks.
  3. Remove any insulation or obstructions from the opening.
  4. Frame the rough opening by adding 2×4 lumber to the sides and top. Ensure the header (the horizontal piece at the top) is level.
  5. Secure the framing with nails or screws, making sure it is plumb and square. Use shims as needed to make adjustments.

Install a Sill Plate (if needed)

  1. If your door requires a sill plate, install it at the bottom of the rough opening, ensuring it is level and properly aligned.

Apply Construction Adhesive

  1. Run a bead of construction adhesive along the inner edges of the rough opening frame to help secure the door frame.

Install the Door Frame

  1. Carefully place the door frame (jamb) into the rough opening, making sure it’s level and plumb.
  2. Shim the frame at the bottom, top, and sides to ensure it’s perfectly aligned and level.
  3. Secure the door frame to the rough opening using screws or nails. Drive fasteners through the shims into the framing, being careful not to over-tighten and distort the frame.

Check for Squareness

  1. Use a carpenter’s square to check that the door frame is square. Adjust the shims as needed until it’s perfectly square.

Check for Plumb

  1. Check that the door frame is plumb on both sides. Make any necessary adjustments using shims.

Insulate and Trim

  1. Add insulation around the door frame to prevent drafts.
  2. Install the interior and exterior trim or casing, following the manufacturer’s instructions.

Hang the Door

  1. Hang the 36-inch door slab onto the hinges, following the manufacturer’s instructions.
  2. Test the door for proper operation, making sure it opens and closes smoothly.

Apply Weatherstripping and Hardware

  1. Install weatherstripping to seal any gaps between the door and frame.
  2. Install the door hardware, including the handle, latch, and deadbolt, according to the manufacturer’s instructions.


  1. Finish the door and frame with paint or stain to protect them from the elements.

By following these steps, you can build a solid rough opening for a 36-inch door that is level, plumb, and properly aligned, ensuring the door operates smoothly and provides a secure seal when closed.