How to Replace Your Internal Doors

The Step-by-Step DIY Guide

The DIY Checklist:
What You’ll Need

Upgrading your home's internal doors is a highly effective way to modernise your living spaces, improve heat insulation, and reduce draughts. In Ireland, older properties often have non-standard frame sizes due to settling over time, whereas newer builds typically follow standard metric configurations. Replacing a door involves careful planning, precision cutting, and setting up the correct hardware suite to ensure a perfect swing.

1.

SAFETY
GEAR
(PPE)

Safety Glasses: Essential eye protection against flying sawdust, wood splinters, and metal shavings when trimming doors or chiselling out hinge recesses.

Dust Mask (P2 or FFP2): Highly recommended when cutting, sanding, or planing timber or composite materials to avoid inhaling fine wood particles.

Ear Muffs / Ear Defenders: Important protection when operating high-speed circular saws or electric planers.

2.

TOOLS &
EQUIPMENT

Spirit Level: Essential for checking that your frame casing is plumb and level before hanging the new door.

Hand Saw or Circular Saw: Used for trimming the height of the door down to size.

Wood Chisels (12mm & 20mm): Extremely sharp bevelled edge chisels to mortise out neat hinge flaps and strike plate recesses.

Electric Planer or Hand Planer: Crucial for shaving off millimetre-perfect strips along the sides of the door to get a smooth, non-binding fit.

Cordless Drill & Driver Bits: For boring pilot holes and screwing hinges, latches, and handle plates securely into place.

Sharp Pencil or Utility Knife: For marking precise measurement lines and scoring timber grain to prevent splitting when chiselling.

3.

Materials, Fixings & Accessories

Internal Doors (Various Sizes): High-quality hollow-core, semi-solid, or solid timber doors. Popular Irish sizes include 1981mm x 762mm and 1981mm x 813mm.

Hinges, Handles & Locks: Typically, two or three 75mm (3-inch) brass or steel butt hinges per door, plus matching internal latch and handle assemblies.

Linings & Architrave (Optional): Wooden frame kits and decorative architrave timber trim sets to replace warped or damaged door surrounds.

Expandable Foam & Shims: Low-expansion polyurethane foam and wooden wedges to securely shim and level the door linings inside wall openings.

Screws & Fixings: Wood screws (typically 4.0mm x 30mm for hinges and latch plates) and frame fixings.

Wood Filler & PVA Glue: Premium timber filler to patch screw holes or blemishes, and wood glue to strengthen frame joints.

Top Tip: Know Your Trimming Limits!.

Most standard budget hollow-core doors have a very thin internal timber frame (called a lipping). You can usually only shave a maximum of 5mm to 10mm off each vertical side before compromising the structural core. If you need to trim more than this to fit an awkward or settled Irish door frame, always opt for semi-solid or solid wood doors which can be cut down substantially.

Top Tip: Maintain the Standard 3mm Clearance Gap.

For a professional, bind-free swing, aim for a consistent 3mm gap at the top and both vertical sides of the door. The bottom clearance should be 5mm to 10mm to clear hard flooring, or up to 15mm if you are fitting thick carpets or underlay. Use a 2 Euro coin as a handy 2.2mm spacer gauge to quickly check gaps during installation!

Step-by-Step DIY Installation Guide

STEP

01

Measure Your Existing Frame

Measure Width and Height:

Take three horizontal measurements of the frame opening (top, middle, bottom) and two vertical measurements (left and right sides). Use the largest measurements to choose your replacement door size.

Check for Squareness:

Use a spirit level along the inside frame casings and measure diagonally across the corners to see if the frame has settled out of square.

STEP

02

Trim the Door to Size

Mark Up Adjustment Lines:

Hold the new door up against the frame opening. Use wood wedges on the floor to lift it up, leaving a 3mm gap at the top. Mark the edges of the frame directly onto the door face.

Plane or Saw the Edges:

Lay the door flat on solid workbenches. If you need to trim more than 6mm off the height, use a circular saw fitted with a fine-toothed blade. For shaving small amounts (1mm to 5mm) off the vertical sides, run your electric planer slowly down the edges, keeping it completely flat.

STEP

03

Mark and Cut Hinge Recesses

Mark Hinge Positions:

On the hinge side of the door, measure and mark 150mm down from the top edge, and 230mm up from the bottom edge. Place your hinge flat against the door edge at these marks and trace around them with a sharp pencil.

Chisel the Mortise:

Use your utility knife to score deeply along your pencil marks to prevent the wood grain from tearing. Carefully use a 20mm wood chisel and mallet to chip away the wood inside the outline to a depth equal to the thickness of the hinge plate.

STEP

04

Mount Hinges and Hang the Door

Fix Hinges to the Door:

Drill small pilot holes to prevent the timber from splitting, then screw the hinge plates firmly into their door recesses using your cordless screwdriver.

Transfer to the Frame Casing:

Support the door in the open position inside the frame using wedges. Mark the hinge plate positions onto the vertical door frame jamb. Chisel out matching mortise recesses on the frame, drill pilot holes, and screw the hinges home to hang the door.

STEP

05

Fit Latch, Strike Plate, and Handles

Drill for Latch:

Measure the height of your existing handle strike (usually around 1000mm up from the floor). Hold your new latch against the door edge, mark its position, and drill a deep bore hole using a flat wood spade bit. Drill a perpendicular intersecting hole through the door face for the handle spindle.

Recess the Faceplate:

Push the latch into its edge hole, draw around the faceplate, chisel a shallow recess so it sits flush, and screw it in. Install the spindle and screw your new handles onto both faces of the door.

Attach the Strike Plate:

Gently close the door to mark where the latch tongue hits the frame. Position the metal strike plate over this mark, chisel a shallow recess into the door frame jamb, and screw it into place.

STEP

06

Install Architrave & Finishing Touches

Renew Trim (If required):

If you are replacing the framing linings or architrave trim, cut your timber moldings to size with a mitre box at 45-degree corner angles. Glue and nail them flat against the wall casing.

Fill and Seal:

Apply wood filler to any exposed nail heads, screws, or joints. Lightly sand flush when dry before painting or staining.

How to Replace Your Internal Doors: Irish DIY Guide

Internal Door Replacement Calculator

1. Define Your Internal Doors

Location Label

Target Standard Size

Replace Frame?

2. Configuration Options

Preview Door Row:

Hinges Per Door:

Wastage & Spares Buffer:

Hanging Door Clearance & Detail Preview

Estimated Basket Materials Required

Total Doors Required: 0 Slabs

Hinges Needed: 0 Individual Hinges

Door Handle & Latch Sets: 0 Sets

Frame Linings Kits: 0 Kits

Architrave Timber Sets: 0 Sets

Shim Wood Packs & Foam: 0 Packs

Wood Filler & PVA Glue: 1 Pack

Standard Retail Basket Yield Rules:
• Hinges: Solid core doors require 3 hinges to prevent warping. Light doors can utilize 2 hinges.
• Architrave Sets: One standard architrave pack covers one full door opening face on both sides (front and back casings).

DIY Project Shopping Checklist

Internal Door Replacement Shopping Manifest

Calculated Project Scope: 0 Replacement Door(s) Planned

1. Dynamic Calculated Materials & Core Basket Items

GOT IT	MATERIAL DESCRIPTION	TARGET QUANTITY REQUIRED
☐	Standard Internal Door Slabs (selected profiles)	0 Slabs
☐	Steel or Brass Butt Hinges (75mm / 3-inch size)	0 Individual hinges
☐	Door Handle Sets & Matching Internal Tubular Latches	0 Sets
☐	Wooden Door Lining/Casing Frame Kits	0 Kit(s)
☐	Moulded Architrave Timber sets (covering front/back frames)	0 Set(s)
☐	Timber Shims & Low-Expansion Polyurethane Foam Canister	0 Pack(s)
☐	Premium Interior Wood Filler & Waterproof PVA Wood Glue	1 Pack
☐	High-performance wood screws (4.0mm x 30mm box of 200)	1 Box

2. Required Tools & Accessories Package

GOT IT	TOOL NAME	APPLICATION PURPOSE
☐	Electric Planer or Hand Planer	For shaving millimetre-precise strips along vertical edges to fit out-of-plumb frames
☐	Bevelled Edge Wood Chisels (12mm and 20mm sizes)	To carve flat, recess-perfect hinge flaps and lock strike pockets
☐	Hand Saw or Circular Saw	For cutting the door height down to size accurately
☐	Cordless Drill & HSS wood driver bits	Bores clean pilot holes and drives fixing screws home quickly
☐	Spirit Levels (600mm & 1200mm sizes)	Ensures vertical linings and frames hang level with no binding
☐	Sharp Pencil & Retractable Utility Knife	To mark cutting lines and score wood fibers to prevent splitting

3. Mandatory Safety Gear (PPE)

GOT IT	SAFETY ITEM	PROTECTION STANDARD
☐	Impact Shielding Wrap-Around Safety Glasses	Guards eyes from wood splinters and airborne planer chips
☐	FFP2 / P2 High-Efficiency Particulate Dust Mask	Filters hazardous timber and composite MDF core dust particles
☐	Noise-Cancelling Ear Muffs / Defenders	Crucial ear protection when using loud planer and saw motors

Present this custom calculated summary list to the building merchant counter assistant to build your project basket easily.

How to Replace Your Internal Doors

The DIY Checklist: What You’ll Need

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Step-by-Step DIY Installation Guide

STEP

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STEP

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STEP

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Internal Door Replacement Calculator

Estimated Basket Materials Required

DIY Project Shopping Checklist

1. Dynamic Calculated Materials & Core Basket Items

2. Required Tools & Accessories Package

3. Mandatory Safety Gear (PPE)

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The DIY Checklist:
What You’ll Need