--- title: "How to Case One Side of an 8'0\" Door" description: "On this page[Introduction](#)[Before You Begin](#)[Prerequisites](#)[What You Need To Know](#)[Tools](#)[Materials](#)[Installation Steps](#)[Step 1. Measure and Cut Casing](#)[Step 2. Install Head Casing](#)[Step 3. Attach Side Casings](#)[Step 4. Check and Adjust Alignment](#)[Pro Tips](#)[Common Mistakes](#)[QC / Punch Checklist](#)[Related Guides](#)[Overview](#lbs-field-overview)[Steps](#lbs-field-steps)[Checks](#lbs-field-checks)[Fix a problem](#lbs-field-fix) [Moldings](/learn-category/moldings/) Skill Level: [Beginner…" url: "https://letsbuildstuff.co/learn/case-one-side-door-80/" updated: "2026-09-24" category: Moldings tags: - Level 1 - Supplemental Guide --- # How to Case One Side of an 8'0" Door On this page[Introduction](#)[Before You Begin](#)[Prerequisites](#)[What You Need To Know](#)[Tools](#)[Materials](#)[Installation Steps](#)[Step 1. Measure and Cut Casing](#)[Step 2. Install Head Casing](#)[Step 3. Attach Side Casings](#)[Step 4. Check and Adjust Alignment](#)[Pro Tips](#)[Common Mistakes](#)[QC / Punch Checklist](#)[Related Guides](#)[Overview](#lbs-field-overview)[Steps](#lbs-field-steps)[Checks](#lbs-field-checks)[Fix a problem](#lbs-field-fix) [Moldings](/learn-category/moldings/) Skill Level: [Beginner (Level 1)](/learn/difficulty-levels/#level-1) · Estimated Time: 45-60 Minutes Per Door ## Introduction Casing one side of an 8'0" door is a staple task in [finish carpentry](/learn/trim-a-house/), especially in new construction and remodels. This process involves installing trim around the door to cover the gap between the door frame and the wall, providing a polished look. A well-cased door enhances the aesthetic of any room and ensures a seamless transition between spaces. The single most important concept in this task is achieving tight, clean miters and ensuring that the casing is [flush](/glossary/layout-and-shop-talk/#flush) with the wall and jamb. This attention to detail is what separates professional results from amateur attempts. This guide covers an interior door; if you're casing an [exterior door](/learn/install-exterior-door/) instead, see our [exterior door casing guide](/learn/install-exterior-door-casing/) for the extra weather-side details that come with it. ## Before You Begin Before you case the door, confirm that the following prerequisites are complete. ### Prerequisites - Drywall installation and finishing are complete. - Flooring is installed, or allowances are made for its thickness. - [Door is hung](https://letsbuildstuff.co/learn/install-pre-hung-door/) and swings correctly. ### What You Need To Know When you case the door, understanding these core techniques will save you time and prevent callbacks. - Ensure case miters are properly aligned to avoid gaps. - Check for any separation between door casings and walls. - Use a [jamb extension](/glossary/moldings/#jamb-extension) if needed to case out a door properly. If the opening you're casing has no door slab at all, our [cased opening guide](/learn/install-cased-opening/) walks through that variation instead. ## Tools - Miter Saw - for precise angle cuts on casing. - [Finish Nailer](/recommends/dewalt-dcn650-amazon) - for securing the casing to the wall and jamb. - Level - to ensure the casing is [plumb](/glossary/layout-and-shop-talk/#plumb-level-square-condition) and aligned. - Measuring Tape - for accurate measurements. - [Utility Knife](/glossary/tools/#utility-knife) - for trimming and scoring as needed. ## Materials - Door Casing - typically [MDF](/glossary/materials/#finger-joint-fj-primed-clear-pine-poplar-oak-maple-mdf) or prime pine for paint-grade applications. - Finish Nails - 15-gauge, 2-1/2" for securing casing. ## Installation Steps ### Step 1. Measure and Cut Casing Start by measuring the door opening and cutting the casing to length. Use a [miter saw](/glossary/tools/#miter-saw-12in-sliding-compound) to cut 45-degree angles for the top corners. - Measure the [head casing](/glossary/moldings/#head-casing) first and cut to length. - Cut side casings with mitered tops to match the head casing angles. ### Step 2. Install Head Casing Position the head casing above the door, ensuring it is level and centered. Secure it with [finish nails](/glossary/materials/#pin-brad-finish-nail-casing-nail-collated). - Use a level to ensure the head casing is perfectly horizontal. - Nail it into place with 2-1/2" finish nails, spacing nails every 16 inches. ### Step 3. Attach Side Casings Align the side casings with the head casing miters and secure them to the wall and jamb. - Check that the miters are tight and adjust as needed. - Nail the casing to the jamb and wall, ensuring it is flush. ### Step 4. Check and Adjust Alignment Ensure all casings are flush with the wall and jamb, adjusting as needed for a clean finish. - Use a level to check for plumb and adjust if necessary. - Ensure there are no gaps between the casing and the wall. ## Pro Tips **Pro Tip:** "Some case miters look like shit, mostly basement and main floor" - Ensure your miters are tight and well-aligned to avoid unsightly gaps. **Pro Tip:** "Cleaned up old casing to be reused" - Reusing old casing can save on materials and maintain consistency in appearance. ## Common Mistakes - **Mistake:** Misaligned miters - This happens when cuts are not precise. Ensure your miter saw is properly calibrated. - **Mistake:** Gaps between casing and wall - Often due to uneven walls or improper nailing. Check alignment and re-nail as needed. ## QC / Punch Checklist - Verify all miters are tight and aligned. - Ensure casing is flush with the wall and jamb. ## Related Guides - [How to Case One Side of a 6'8" Door](https://letsbuildstuff.co/learn/case-one-side-door-68/) - [How to Install a 6'8" Cased Opening](https://letsbuildstuff.co/learn/install-6-foot-8-inch-cased-opening/) Written by **David Hospodka**, Sun’s Up Construction David Hospodka learned finish carpentry from his father, alongside his brother Joel, and worked his way through college trimming houses. He then spent about ten years as a railroad bridge engineer, handling design, construction, maintenance and project management. He came back to finish carpentry full time in 2017. [About Let’s Build Stuff](https://letsbuildstuff.co/about/)