Rough Opening for a 36 Inch Door

Welcome to a comprehensive guide on creating a rough opening for a 36-inch door. Whether you’re a DIY enthusiast or a professional contractor, understanding the process of preparing the opening for a door is crucial. In this article, we’ll break down the steps and considerations to ensure your door installation goes smoothly.

Gathering Tools and Materials

Before you start, make sure you have all the necessary tools and materials:


  • Measuring tape
  • Pencil
  • Level
  • Circular saw
  • Hammer
  • Screwdriver
  • Chisel
  • Safety gear (goggles, gloves, ear protection)


  • 2×4 lumber
  • Door framing kit
  • Screws
  • Shims

Measuring and Marking

Accurate measurements are key to a successful door installation. Follow these steps:

Measure Door Dimensions

  • Measure the width and height of your 36-inch door.

Mark the Rough Opening

  • Mark the centerline of the door on the wall.
  • Use a level to draw a plumb line from the top to the bottom of the opening.

Framing the Rough Opening

Proper framing ensures the door fits securely. Here’s how to frame the rough opening:

Header Installation:

  • Cut a 2×4 piece of lumber to the width of the rough opening. This will serve as the header, providing support at the top of the door frame.
  • Position the header at the top of the rough opening, making sure it aligns with the markings you’ve made earlier.
  • Secure the header in place by nailing it to the surrounding framing. Ensure it’s level and well-secured.
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Side Framing:

  • Cut two 2×4 pieces of lumber to the height of the door. These will be used for the vertical sides of the rough opening.
  • Nail one of these pieces on each side of the opening, ensuring they are plumb. Plumb means perfectly vertical.

Bottom Plate:

  • Cut a 2×4 piece of lumber to the width of the rough opening. This piece will act as the bottom plate, providing stability to the door frame.
  • Place the bottom plate at the bottom of the rough opening and secure it by nailing it securely to the floor or subfloor.

Properly framing the rough opening ensures the door is well-supported, preventing issues like sagging or misalignment. These steps provide a strong and stable structure for your 36-inch door.

Door Installation

Insert Shims

Begin by placing shims underneath the door. Shims are used to level the door within the rough opening. Insert shims at various points under the door as needed to ensure that it sits level and plumb.

Mount the Door

Position the door in the rough opening, making sure it aligns with the markings you made earlier. Ensure that there’s a small and even gap around the door frame.

Secure it using screws or nails through the jamb

Once the door is correctly positioned, secure it in place. Drive screws or nails through the door jamb into the surrounding framing, including the header, side framing, and bottom plate. Ensure the door is held securely and doesn’t move.

Properly installing the door within the rough opening is a critical step to ensure it operates smoothly and fits correctly. The use of shims and secure fastening will help maintain the door’s alignment and stability.

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Checking for Alignment

Check for Plumb

Use a level to determine if the door is perfectly vertical, or “plumb.” Place the level against the sides of the door frame, both on the hinge side and the latch side. If the bubble in the level’s vial rests between the two lines, the door is plumb. If not, you may need to adjust the shims or hinge placement to correct it.

Test the Swing

Open and close the door to ensure that it operates smoothly. Pay attention to any resistance or rubbing. A well-aligned door should swing freely without any obstructions or sticking. If you encounter any issues, you may need to make further adjustments to ensure the door’s proper operation.

Finishing Touches

Trim Installation

Install trim around the door to give it a polished and professional appearance. Properly fitted trim not only enhances the aesthetics but also covers any gaps or imperfections in the door frame.

Hardware Installation

Attach the essential hardware components to your door to make it functional and secure:

  • Doorknob: Install the doorknob, ensuring it operates smoothly and locks securely. Follow the manufacturer’s instructions for proper placement and alignment.
  • Lockset: Attach the lockset to provide security and privacy. Ensure that it functions correctly and aligns with the strike plate on the door frame.
  • Hinges: Secure the door to the frame using hinges. Make sure they are properly aligned, and the door swings smoothly without obstruction.

Completing these finishing touches not only improves the functionality of the door but also adds a polished and attractive look to your installation.

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Here are answers to the frequently asked questions regarding rough openings for a 36-inch door:

How big should a rough opening be for a 36-inch door?

The rough opening for a 36-inch door should be approximately 38 inches wide and 82 inches tall. This provides a little extra space for the door frame and ensures a proper fit.

How to rough frame a 36-inch door?

To rough frame a 36-inch door, you’ll need to create a framed opening in the wall. Start by installing a header at the top, side framing, and a bottom plate. Ensure that the framing is level and plumb, and then mount the door within this rough opening.

How do you calculate the rough opening for a door frame?

To calculate the rough opening for a door frame, measure the width and height of the door, and add approximately 2 inches to the width and 2 inches to the height. This additional space accommodates the door frame and allows for adjustments during installation.

How much space should be between the door frame and the rough opening?

There should be a small gap between the door frame and the rough opening, typically around 1/8 to 1/4 inch on all sides. This gap allows for adjustments and ensures a proper fit without binding.

What gap do I leave for a door frame?

When installing a door frame, leave a consistent gap of approximately 1/8 to 1/4 inch between the frame and the rough opening. This gap provides space for shimming and adjustment during installation.

How far off the floor should a door be?

A typical interior door is hung with the bottom of the door about 1/2 inch above the finished flooring. This clearance allows for the door to swing freely and prevents it from rubbing against the floor covering. However, this distance can vary depending on the flooring material and personal preference.


Creating a rough opening for a 36-inch door is a fundamental skill for anyone involved in construction or DIY projects. With the right tools, materials, and a step-by-step approach, you can achieve a professional-looking installation that ensures your door fits and operates perfectly.