How To Measure 

   Measuring window and door openings is a simple process

   which will result in reduced lead times and eliminates the

   need for a site survey ultimately saving you money! 

Simple Measurement Steps 

  • Always measure the opening from the external leaf of the wall.
  • Always measure the exact opening from brick to brick or lintel to brick - And NOT your old windows/doors.  
  • Measure the width in at least three different places, only providing the smallest dimension.
  • Measure the height in at least three different places, only providing the smallest dimension.
  • All dimensions to be taken in metric units.
  • All designs/opening configurations to be viewed as from the outside. 

When measuring the openings for doors please take into account the door threshold in comparison to your finished floor level and how high/low you would like your threshold to be set. Please refer to product specific threshold details. If in doubt please get in touch.

Taking into account the height of the door threshold is important for the following reasons;

  • If you require a flush threshold it is important the external leaf of your wall and your finished floor level are the same height, minus the height of the door threshold. This will then provide completely flush threshold.
  • If finished floor levels are set higher than your door threshold it may result in your doors not operating adequately. I.e whilst opening your doors, the door sashes may rub against the finished floor level and therefore not provide a smooth opening operation.  
Please Note: It is not always possible to provide a completely flush threshold as this is determined by the door system you intend to purchase.  

When measuring door openings always measure to the underside of the door threshold and door sill if required. Taking into account the internal finished floor level and the height of the door threshold and sill. The difference between the floor levels will determine what level to position your doors to achieve a minimal threshold lip.  


Once we are in receipt of the opening sizes, we will allow the necessary tolerance for your products to fit perfectly into prepared openings. 

In general a 15mm tolerance will be deducted from the overall height of the opening and a 15mm tolerance from the overall width of the opening. This tolerance allows for your windows/doors to sit flush into the opening allowing for any packing/levelling required. Once the product is plumb and square in the aperture, spacers/packers and direct fixings will then be utilized to secure the frame into place. All frames will be mastic sealed with colour coded mastic, providing a professional finish and weather protection.    

All make sizes and opening configurations/design will be reconfirmed prior to fabrication works. 

All dimensions provided will include the frame, sill and threshold.  

For Further Information Including a Quote Please Call 0333 772 9632 - Our Experts Would Love To Help!


Tel: 0333 772 9632
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