How to measure up

How to measure your door opening

Our guidance is to help you get the most accurate door measurement for your external doors. If you have concerns about measuring your door opening, we suggest getting a local door fitter to carry out a professional measurement. 

The structural opening of a standard door

  • The Structural opening of your door is the brickwork to brickwork measurement.
  • Always measure your opening from the outside.
  • Measure the width & height, brick - brick taking three measurements from the left hand side to the middle and the right hand side. As per below images.


How to allow for side panels
  • Your side panel measurement needs to be taken from the outer frame of the door to the edge of the brickwork
  • Careful consideration needs to be taken when ordering side panel's 
  • If your overall structural opening is 1425mm and your main door + frame is 920mm, this leaves you 505mm overall to split between your side panel / panels. 
  • Don't forget to allow the 5mm fitting tolerance around the entire perimeter

How to allow for top lights 

  • As above, the top light measurement needs to be taken from the outer frame of head (Top of doorframe) to the edge of brickwork
  • If your overall structural opening is 2400 and your main door + frame is 2100, this leaves you 300mm for the toplight
  • Do not forget to allow for the 5mm tolerance around the entire perimeter 

Tolerance & fitting

  • Please allow a 5mm tolerance around the perimeter of the entire dimensions you take. This is vital to allow for fitting
  •  This will give a tolerance for adjustment when your fitters pack the frame out while fitting. 
  • Once the door and frame are fitted, checking all angles are plumb with a spirit level, the packers can be cut back and the frame sealed with silicone. 
  • Other options are to use expanding foam. Cut back, then use a UPVC trim to tidy the finish.
  • Mortar pointing may be required if the bottom cill projects beyond the structural opening

Key information to remember prior to ordering.

  • Always measure from the outside brickwork to brickwork
  • Take three measurements & deduct 10mm from the overall size i.e. structural opening of 2100mm x 910mm Door order size 2090mm x 900mm
  • Ensure the overall size you enter on our door builder is smaller than your structural opening
  • All dimensions on the door builder are in metric (MM) 
  • All designs are as you are viewing from the outside
  • We can even colour match the internal colour of the door if required
  • We do not make allowances for incorrect dimensions supplied by customers
  • In most cases, if you order a door & frame too small you can purchase a packing piece.

All doors come with our Ultion guarantee. £1000 if your door gets broken into & a replacement door!