Easy bifold door installation with our measurement and fitting guide

Surveying for bifold doors is similar to measuring up patio doors, but there are some additional points to consider before ordering. Save time, money and hassle by reading our measurement and installation guide.

How to measure bifold doors

Before ordering your bifold doors, you’ll need to precisely measure the aperture in which the door set is going to be installed.

  • Measure the width at 3 separate levels and use the smallest width for your order.
  • Measure the diagonals from corner to corner, and check that the area is a perfect square.
  • Order the door (overall height and width) 10mm shorter and 10mm narrower than the opening that you plan to install it into. This gives you the tolerance to pack out the frame of the door using plastic or timber wedges or packers when installing it to get the frame square and plumb.

If the frame is ordered exactly the same size as the opening, you will have difficulty getting the door in position and you will not be able to adjust the level of the frame. Remember, it’s very unlikely that the opening will be perfectly square.
Doors must be viewed from the outside when ordering – this is important when specifying opening options.

Questions to ask your customer

  • Which way do you want the door to fold, into or outside the property?
  • Which way should the doors travel when opening: right, left or out from the middle?
  • Does your customer want a ‘traffic’ door as a main opener for daily use?
  • Consider the floor level – allow for carpet, wooden floors, tiles and patio slabs
  • Outer frame sizes from Alex Trade includes the bottom track height

How to install a bifold door

Installing bifold doors is similar to other glazing products, so please also consult our other guides to installing windows and doors, and toe and heeling glazing first. There are a few differences, however.


To guarantee your bifold doors are glazed in the correct manner, remove all glazing beads and apply the necessary bridge packers. Toe and heel each unit from the ground upwards before re-inserting all of the glazing beads in the same positions in which they were removed, width beads first. Finish by inserting the wedge gaskets between glass unit and beading.


For perimeter sealing use a low modulus neutral cure sealant where necessary and ensure that the drainage channels at the base of the door are free of blockage and debris. Check the operation of the master door panel and then the sliding doors – ensure each glides smoothly along the base track.


When installing bifold doors, make sure to keep the stainless steel track free of dirt and dust, and after finishing, clean by wiping down with a sponge cloth, and refrain from using any chemical solutions. This will ensure you leave your customers with bifolds in the best working condition.