Our top tips for a successful aluminium bifold door installation

With aluminium bifold doors more popular than ever, the demand for bifold door installations is especially high.

When it comes to fitting aluminium bifold doors, the process doesn’t have to be complicated. As long as you follow the instructions correctly and in the right order, you’re set for a perfect bifold door installation – it’s a bit like assembling flat-pack furniture!

At The Builders Choice, we supply contemporary aluminium bifold doors to the trade, delivering directly to your site, ready for a successful installation.

We have an informative step-by-step video to guide you through the bifold doors installation process, complete with useful tips and tricks. You can watch the video here:

Measure with precision

Correct measurements are key to ensure that you have a smooth bifold door installation.

  1. Begin by checking the aperture or space for the new bifold door is completely flat, level, straight, plumb and square at every side.
  2. Take 3 measurements for the aperture’s height, width and diagonals, so that the opening is completely equal on each side. Leave a 10mm tolerance between the frame and opening and consider the internal floor finish too. There should be no load bearings on any part of the frame once it is fitted.
  3. The smallest height and width measurements that you take will determine the overall frame size, ready for manufacturing.

Prepare for fitting

Once delivered, you are now ready to start the bifold door installation.

  1. Make sure you have all the components that you need to complete the installation – such as cills, add-ons, gaskets, trickle vents, packers.
  2. There should be a solid structure to fix the frame onto, completely clean and clear of any old silicone or debris. Double check the size of the opening against the bifold door outerframe to ensure correct measurements.
  3. We supply all our aluminium bifold doors fully packaged and protected to avoid potential damage. Carefully remove the packaging without cutting across the face of the bifolds. You will find the keys and fittings attached to the inner master door and frame.

Fit the cill

Once you’ve double checked the aperture is completely clear and level, it’s time to install the cill.

  1. Cut the end caps to the correct length, then silicone the end of the cill before fixing the caps in place. If additional cill height is required, use a continuous packer underneath the cill to achieve your desired height. If the base or brickwork isn’t level, use packers under the cill to stabilise.
  2. Check there’s at least a 25mm overhang from the face of the building, then set the cill in place. We recommend that you use silicone instead of screws to hold the cill in place.
  3. Now check that the cill is absolutely level and that all measurements are correct, then fix the back edge of the cill in place, ensuring all drainage holes are free and not blocked.

Position the bifold

The bifold doors can now be positioned onto the cill and into the aperture.

  1. To position the bifold, ensure the top and bottom remain both plumb and square. If using straps to support the bifolds during the installation, fix them in place.
  2. Remove the threshold gasket and fix the frame to the cill. The first fixing should be placed 150mm above the bottom corner.
  3. Even out the fixings approximately 600mm apart and make sure the clearance of the master sash is at least 5mm clear of the keep. Do not over-tighten the fixings and use packers around the fixings to prevent distortion of the frame.
  4. Remove the 2mm cover gaskets and fix the final frame fixing screw, then put the gasket back in place.

Adjustable jambs

All our aluminium bifold doors come with handy adjustable frame jambs on both sides, to help overcome any irregularities in the wall structures.

  1. If the bifold is not fully square and plumb once fitted, you can adjust the jambs on either side to a 4mm tolerance. Simply remove the gasket, loosening the main frame fixing screws and the screws on the face by the same number of turns.
  2. Then, with a 4mm Alan key, wind the jambs to the desired distance, then re-tighten the screws and put the gasket back in place.
  3. Once all the doors are working as they should, you can fix all the final fixing screws to the internal and external hinges.

Fit the glazing in place

Before fitting the glazing, lock all door panels and fully engage the locks. Ensure the captive gasket is pushed all the way into the bed and remove the top and side beads from the first door leaf.

  1. It’s crucial that all the door leafs are toe and heeled correctly. If incorrect, it will result in the doors not opening properly.
  2. Use glazing packers to pack the bottom corner of the hinge side and top corner of the opposite side on the furthest door leaf from the master door.
  3. Lift the glass into place and fit extra packers where needed. Refit the beading into the same position it was removed from and repeat the process for each door.
  4. Check the measurements are correct between the door leaf and outerframe then fit the wedge gaskets. To help with fitting, you can dip the gaskets in warm soapy water. Provide at least an extra inch in length to allow for a small amount of movement or shrinkage.

Add door magnets

Top tip: fit door magnets between the leafs when they are open.

  1. Position the door leaf at the point where it will stop, ensuring clearance between the door and the lever handle. Fix the magnet using the fixings supplied and ensure the position of the anti-rotation screw is pointed toward the hinged side.
  2. Join the magnets together to locate the position needed on the opposite door panel. Mark the position for the panel catch and fix in place. Then screw the outer magnet sleeves into place.

Complete the installation

Once installed, ensure that the doors are in full working order, fully sealed both internally and externally.

  1. Always give a full demonstration to your customer on how to operate their new bifold doors and provide them with an End User Manual. Ensure that they are aware to always open and close the doors in the correct sequence.
  2. Make sure to clean down and clear up any mess you’ve made.
  3. And you’re all done!

We hope our guide is useful when you next come to fit bifold doors! If you’re looking for more help, or have any questions about bifold door installations, get in touch with us today. You can call 01772 603 303 or email

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