Step-by-Step: Installing Pre-Assembled Doors in Half the Time

Jaeson Ibarra
Step-by-Step: Installing Pre-Assembled Doors in Half the Time

Why Pre-Assembled Doors Are Changing the Game

Traditionally, installing doors has been a labour-intensive task requiring time, accuracy, and a variety of equipment. It might take hours or even a full day to install a new door, from lining up the hinges to ensuring the frame is precisely square.

Let's talk about pre-assembled doors. These are sometimes referred to as door sets or pre-hung doors since the door slab, hinges, and frequently the latch mechanism are already attached to the frame. This results in a far faster installation process, significantly less on-site labour, and less equipment.

In this guide, we’ll walk you through:

  1. The advantages of pre-assembled doors.
  2. The tools and materials you’ll need.
  3. A step-by-step installation process.
  4. Common mistakes to avoid.
  5. Aftercare tips to make your door last.

Chapter 1: What Are Pre-Assembled Doors?

Complete door units with the door slab already mounted on its hinges inside the frame are known as pre-assembled doors. For outdoor doors, the weather seals, strike plate, and latch could even be pre-installed.

Key features:

  • Door slab and frame arrive together.

  • Pre-fitted hinges for perfect alignment.

  • Latch or lock mechanism is often included.

  • Adjustable frame options for uneven walls (in some models).

These are widely used for both internal and external purposes. Homeowners adore them because they appear well-fitted from the beginning, and builders adore them because they save installation time.

Chapter 2: Why Choose Pre-Assembled Doors? (Benefits & Advantages)

Installing a pre-assembled door offers several advantages compared to fitting a door from scratch.

1. Time-Saving

Marking hinge locations, chiselling recesses, fastening the door to the frame, and adjusting until everything lines up are all part of the conventional door fitting process. All of the labour is completed at the manufacturer when using a pre-assembled item.

UK Stat: Many fitters report cutting installation time from 3–4 hours to under 90 minutes.

2. Precision Alignment

The likelihood of binding or uneven gaps is decreased by factory assembly, which guarantees uniform hinge positioning and a smooth swing.

3. Fewer Tools Required

Since the fiddly joinery work is already done, you’ll need far fewer tools — ideal for DIYers.

4. Consistent Quality

Factory finishing means every unit is square, plumb, and aligned to exact tolerances.

5. Better for Bulk Projects

Pre-assembled sets make changing many doors at once easier and preserve the same aesthetic throughout your house.

Chapter 3: Tools & Materials You’ll Need

While pre-assembled doors make the job easier, you’ll still need some basic tools:

  1. Tape measure
  2. Spirit level (at least 1.2m)
  3. Cordless drill/driver
  4. Screw bits
  5. Shims/wedges
  6. Hammer and nails (or nail gun)
  7. Sealant and caulking gun (for external doors)
  8. Safety goggles and gloves

Chapter 4: Step-by-Step Installation Guide

Here’s the complete process.

Step 1: Measure the Door Opening

Before ordering your door set, measure:

  • Width (top, middle, and bottom)

  • Height (left and right sides)

  • Wall thickness (important for frame fit)

Tip: Always measure in millimetres for accuracy.

Step 2: Prepare the Opening

  • Remove any old door frame, architrave, and fixings.

  • Clean away dust, debris, and old sealant.

  • Check the opening is level and plumb. If not, be prepared to shim.

Step 3: Position the Pre-Assembled Door

  • Place the unit into the opening.

  • Use shims to keep it centred and to adjust for level.

  • Check the gap between the door and the frame on all sides (should be even).

Step 4: Secure the Frame

  • Drill pilot holes through the hinge side first.

  • Screw the frame into place, checking alignment as you go.

  • Repeat for the latch side.

Step 5: Check Operation

  • Open and close the door several times.

  • Ensure it latches smoothly and swings without catching.

  • Adjust shims if necessary.

Step 6: Install Architrave & Finishing Touches

  • Fit architrave around the door to cover the gap between the frame and the wall.

  • Fill any screw holes with wood filler.

  • Apply paint, stain, or varnish if required.

Step 7: Seal for External Doors

For external pre-assembled doors:

  • Apply weatherproof sealant around the frame.

  • Check for draughts and adjust seals as needed.

Chapter 5: Common Mistakes to Avoid

  1. Skipping the measurement step — Door sets are not “one size fits all.”

  2. Not checking the level before fixing — This can lead to sticking doors.

  3. Over-tightening screws — This can warp the frame.

  4. Forgetting expansion gaps — Wood and some composites expand in humidity.

Chapter 6: Aftercare & Maintenance Tips

  • Lubricate hinges every 6–12 months.

  • Wipe down regularly with a damp cloth.

  • For painted doors, touch up chips quickly to prevent moisture ingress.

  • For external doors, check seals annually.

Chapter 7: Final Thoughts

For anybody who wants to save time, minimise inconvenience, and achieve a professional appearance, pre-assembled doors are a great option. Installing these door sets may cut your effort in half without compromising quality, whether you're remodelling a single room or your entire house.

For more information about our interior or exterior doors or door accessories, give us a call at 01603 622261 and speak to a member of our expert team today, or email us at sales@doorsuppliesonline.co.uk. We look forward to hearing from you.