How to Fit Bi Fold Doors: Installation Planning Guide
Installing external bi fold doors is a precision job. A wide aluminium frame has to remain square and level, the structural opening needs suitable support, the threshold must integrate with floor levels and drainage, and every panel has to open, fold and lock without being forced. This guide explains the main stages of how to fit bi fold doors so you can plan the project and understand the checks a competent installer should complete.
For a complete system, always follow the manufacturer's installation instructions. Browse our bi fold doors and use the documentation for the exact LPD AluVu product as the final fitting reference.
Professional Installation Is Usually the Best Route
External bifold doors are large, glazed and relatively high-value. Correct installation affects smooth operation, security, weather sealing and long-term alignment. Although it is useful for a homeowner or builder to understand the process, an experienced installer is usually the safest route for a complete aluminium system.
If the installation forms part of a new or widened structural opening, coordinate the door installer with the builder and structural professional before work starts.
1. Confirm the Door Specification Before Delivery
Check the ordered frame size, colour, handing, panel configuration, opening direction and threshold arrangement. Make sure the selected product suits the intended structural aperture.
Use our bi fold door sizes UK guide if the opening and frame dimensions still need to be cross-checked.
2. Confirm the Structural Opening
Measure the finished aperture at the top, centre and bottom for width and at several points for height. Check both diagonals, level and plumb. The opening should provide the fitting tolerance specified for the exact doorset.
Our how to measure for bi fold doors guide gives the full survey process.
3. Check Structural Support Above
A wide opening in an external wall needs appropriate support above it. The lintel or structural beam should be designed for the building loads and installed before the frame. Excessive movement or deflection at the head can interfere with panel operation.
Do not use the doorset frame as structural support for the wall above.
4. Agree the Threshold Datum
Set a clear level for the frame base, finished internal floor and external paving before installation. This is particularly important where the design aims for a low visual transition between inside and outside.
The builder, flooring contractor, landscaper and door installer should work from the same datum so later finishes do not compromise the threshold.
5. Prepare External Drainage
Plan how water will be managed outside the opening. Paving, drainage channels and the doorset cill or threshold need to work together. Do not raise external surfaces against the frame in a way that blocks designed drainage routes.
If the system includes drainage slots or outlets, their location should be understood before sealing and landscaping.
6. Inspect the Doorset on Delivery
Check packaging for damage and compare the delivered components with the order. Confirm frame size, panel quantity, glazing, colour and handing before permanent installation begins.
Do not install a visibly damaged frame in the hope that adjustment will hide the issue. Report transport or component problems before fixing.
7. Store the Components Safely
If installation is not immediate, keep frame sections, panels and glass protected according to the manufacturer's guidance. Avoid storing heavy glazed panels where they can fall, twist or be damaged by other site work.
Keep hardware and small components together and labelled so nothing is lost before fitting.
8. Prepare the Structural Opening
Remove loose mortar, protruding fixings, old sealant and debris. The base should be sound and capable of supporting the frame at the required points. Repair obvious defects before installation.
Dry-check the aperture one final time because structural or plastering work may have changed the dimensions since the original survey.
9. Assemble the Frame if Required
Some systems are supplied in sections that need to be joined on site. Follow the exact sequence for frame joints, gaskets, cill components and sealant. Incorrect assembly can create water paths or dimensional errors that are difficult to correct later.
Keep designed cavities and drainage routes free from excess sealant.
10. Dry-Fit the Frame
Place the assembled frame into the opening before permanent fixing. Confirm that the fitting gaps are appropriate and the threshold sits at the intended level. Check that internal and external finishes can be completed around it.
This is the point to stop if the opening is unexpectedly tight or the frame does not match the order.
11. Level the Base
Use durable support and packers at the points specified by the manufacturer. Check the threshold with a long spirit or laser level. A base that is out of level can create panel alignment problems across the full width of the system.
Do not rely on the frame to bridge unsupported or uneven areas.
12. Plumb the Jambs and Level the Head
Check both side jambs for plumb and the head for level. Measure diagonals repeatedly. Across a wide frame, a small error at one corner can translate into a noticeable difference at the opposite side.
The aim is to keep the entire rectangle true before the fixings are tightened.
13. Fix the Frame Without Distortion
Use suitable fixings and spacing for the frame and building substrate. Fix through appropriate packers so tightening does not pull the aluminium profile out of line. Work progressively around the opening and recheck measurements after each group of fixings.
Do not use screws to force the frame to follow irregular masonry.
14. Install or Rehang the Panels
Follow the manufacturer's numbered sequence for carriers, rollers, hinges and panels. Glazed leaves are heavy, so use appropriate lifting equipment and enough people to control them safely.
The LPD Doors AluVu 8ft Aluminium Bi Fold Door, for example, is a complete system and should be installed using its own hardware arrangement rather than instructions for another brand.
15. Glaze the Panels Where Required
If glazing is installed on site, follow the correct packer and bead sequence. Glazing packers can influence panel geometry and long-term alignment, so they should not be placed randomly.
Use safe glass-handling methods and suitable PPE. Large units are best handled by experienced installers.
16. Set Initial Panel Alignment
Once the panels are installed, close the complete set and inspect the gaps between leaves, the head and the threshold. Use the system's approved adjustment points to bring panels into alignment.
Make small changes and cycle the doors after each adjustment rather than moving several components at once.
17. Test the Traffic Door
If the configuration includes a traffic door, operate it independently. Check that it opens freely, closes against the seals and locks without needing to be lifted or pushed.
A traffic door that is difficult to lock can indicate frame or neighbouring-panel alignment issues.
18. Test the Full Folding Sequence
Open every panel through the complete fold and stack movement. Check for contact at the head, threshold, hinges and stack position. Make sure the panels have sufficient clearance from walls, furniture or exterior features.
Do not force a stiff panel. Identify the cause first.
19. Adjust Locks and Keeps
Test lock operation with the relevant panel open and then closed. If the hardware works smoothly while open but becomes stiff when closed, alignment is likely the issue.
Correct panel geometry before filing, moving or enlarging keeps.
20. Insulate the Perimeter Gap
Insulate the frame-to-building joint using materials appropriate to the installation design. Expanding foam can be one component, but it is not a substitute for correct mechanical fixing or the complete weather seal.
Apply materials carefully so pressure does not bow the frame.
21. Weather-Seal Externally
Seal the perimeter using products compatible with the frame and wall finish. Make the required joint continuous while keeping drainage outlets and designed cavities open.
External sealant should complement the threshold and cill detail, not attempt to replace it.
22. Complete Internal Finishes
Fit trims or make good plaster after the doors have been tested. Protect aluminium surfaces and moving hardware from wet plaster, cement dust and abrasive debris.
Do not cover adjustment points that may need future access.
23. Coordinate Final Landscaping
After installation, make sure patio or decking work respects the threshold and drainage design. Keep paving falls, drainage channels and frame outlets clear.
This step is often overlooked because landscaping may happen weeks after the doors are fitted.
24. Carry Out a Final Handover
Operate the full system several times, test every handle and lock, inspect frame seals and confirm drainage is clear. Give the homeowner any maintenance and adjustment information supplied by the manufacturer.
Photograph the finished frame and threshold before later decorating or landscaping work begins. This can be useful if a problem develops after another trade has altered the surrounding area.
Common Bi Fold Door Installation Problems
Panels Drop After Glazing
Incorrect glass packing, hinge or roller adjustment can affect alignment. Use the system-specific diagnostic method.
The Lock Is Hard to Engage
Check frame square, panel height and meeting-stile alignment before altering keeps.
Panels Rub at the Head
Check panel adjustment, frame level and whether there is any movement or deflection in the structural support above.
Water Appears at the Threshold
Inspect drainage routes, cill joints, perimeter sealing and the level of external paving. Do not block drainage slots.
The Stack Hits an Obstruction
Confirm the configured opening direction and surrounding clear space. This should ideally have been checked before ordering.
Bi Fold Door Installation Checklist
- Correct size, colour and handing confirmed.
- Structural opening measured again.
- Support above completed.
- Threshold datum agreed.
- External drainage planned.
- Frame level, plumb and square.
- Fixings packed without distortion.
- Panels installed in the correct sequence.
- Glazing packed as specified.
- Traffic door and full fold sequence tested.
- Locks operate without force.
- Perimeter insulated and weather-sealed.
- Drainage outlets remain open.
- Final landscaping respects the threshold.
Frequently Asked Questions
Can I install aluminium bifold doors myself?
A highly competent installer may understand the process, but the weight, glazing, precision, structural coordination and weather sealing make professional installation the sensible choice for most projects.
Does the structural opening have to be perfectly square?
Limited variation can be accommodated within the fitting tolerance, but the doorset frame itself needs to be installed square and level.
Can bifold doors sit flush with the patio?
Low-threshold visual transitions can be achieved with suitable systems and construction details, but drainage and weatherproofing still need to be designed correctly.
Why do new bifold doors feel stiff?
Possible causes include debris, frame distortion, panel alignment, roller adjustment or glazing packers. Diagnose the cause rather than forcing the panels.
Should final paving be installed before the doors?
Either sequence can work if the levels are coordinated, but the door threshold and drainage design should be fixed before paving is brought up to the opening.
What maintenance should be explained at handover?
Cleaning, track and drainage care, hardware lubrication where approved and the correct adjustment procedure should all follow the manufacturer's guidance.
Choose the Right Bi Fold System Before Installation
Good fitting begins with the correct size and configuration. Read our bi fold doors buying guide and compare our current aluminium bifold doors before finalising the opening.