Skip to content Skip to navigation menu

Planning & preparation

  • Here we will show you how to replace a standard internal door, including how to trim the door to size and how to find the perfect hanging position
  • When replacing an internal door, the job is made much easier if you can use the same sized hinges and the same hinge positions as the original door. Alternatively, you’ll need to make new hinge positions; these tend to be 150mm from the top of the door and 225mm from the bottom, with an optional third hinge in the centre of the frame
  • Internal doors come in a range of sizes, materials and finishes, so be sure to look at the range and choose a design that best suits your needs
  • Bear in mind that even if you purchase a standard internal door, some door frames, especially those in older houses, may not be a standard size. Therefore, you may still need to trim your new door to fit the existing frame
  • If you do need to trim your door, check the manufacturer’s instructions as the maximum amount that can be removed from the top, bottom and sides of a door varies between products
  • To allow your new door to acclimatise, lay it on a flat and even surface for three days prior to hanging
  • If you are planning to paint your internal door, see our online guides or leaflets ‘How to Prepare Interior Woodwork for Painting’ and ‘How to Paint Interior Woodwork’ for further information
  • For advice on fitting door handles, see our online guide of leaflet ‘How To Fit Door & Window Furniture’

Do it right

  • If you need to trim your door to size, make sure that all reductions are made equally to opposite sides
  • If you are chiselling with the grain, then it can be easy to split the wood. Avoid this by making sure the chisel you are using is sharp and that you make lots of small cuts rather than a few large ones
  • It’s best to drill pilot holes to reduce the chance of the wood splitting

Staying safe

  • Wear safety goggles when drilling and sawing
  • Wear protective gloves when handling timber
  • When using a chisel, be sure to chisel away from the body
  • Secure timber in a workbench when drilling or sawing
  • Internal doors can be heavy so take care when lifting and ask for help if necessary


  • Internal doors need little maintenance but it’s a good idea to keep them clean and free from dirt and dust
  • Be sure to only use products that are suitable for your surface

Step by step

Step 1

Carefully remove the old door, making sure the weight of the door is supported when you remove the final screws.


Step 2

Stand the new door up in the doorway to check whether it needs trimming. If it does, use a pencil to mark the top of the door opening onto the new door.


Step 3

Secure the door to your workbench with clamps. Measure the distance that needs trimming and divide that measurement equally across the top and bottom of the door. Then, add an additional 3mm to both ends to allow for clearance.


Step 4

Carefully mark a cutting guideline on the bottom of the door. If you are only removing a small amount of excess wood, trim using a plane. Alternatively, use a panel saw or circular saw to remove larger amounts. Ensure that you cut in a completely straight line.


Step 5

Now that the door is cut to height, hold it up against the frame to check whether the width of the door fits. If it doesn’t, hold the door so one side is in position and then mark the overhanging distance onto the door.


Step 6

Measure the overhang and divide the measurement equally across both sides. Then add an extra 3mm onto each side to allow for clearance.


Step 7

Draw a cutting guideline then remove the excess wood with a plane or saw.


Step 8

Put the door into position and place small wedges underneath it to lift it off the ground. Position the door so there is a consistent 3mm gap between the door and the frame on all sides.


Step 9

Once the door is in position, use a pencil to mark the position of the existing hinges onto the door.


Step 10

Lay the door onto your workbench and align the hinges you will be using with the marks you made. Carefully draw around the hinges to mark their outline onto the door.


Step 11

Measure the thickness of the hinge plate then mark a line of the same thickness onto the edge of the door.


Step 12

Using a sharp chisel, cut around your pencil lines to clearly mark where the hinges will be situated.


Step 13

Then, position the chisel at a 45-degree angle to the door and, using your pencil mark as a guide, make small cuts at 5mm intervals to the same depth as the hinge plate.


Step 14

Next, turn the flat side of the chisel towards the door and chisel out the recess for the hinge plate.


Step 15

Put the hinges back into position and drill pilot holes. Then, carefully screw the hinge plates to the door using the provided screws.


Step 16

Place the door against the frame and position it so that it is open to 90-degrees.


Step 17

Put the first screw through the lowest hole of the top hinge plate and secure it in place.


Step 18

Then, put a screw through the lowest hole of the bottom hinge plate and secure.


Step 19

Put the third screw into the top hole of the top hinge. Once these three screws are in place, check that the door opens and closes without catching.


Step 20

If the door does catch, simply mark the area that needs trimming, remove the door and then trim down the area with a plane, or with sandpaper and a sanding block.


Step 21

Once the door opens and closes cleanly, carry out finishing touches such as painting the door or making cut-outs for handles or latches. Finally, screw in the remaining screws to secure the door in place.