Fitting a new garage door is a substantial DIY task that is achievable for a competent home improver with the right preparation and assistance. The process varies significantly between door types; this guide focuses on the most common type, the up-and-over door.

Before You Start: Measure Carefully

Accurate measurement of the opening is the most critical step. Measure the clear opening width (between masonry jambs) at the top, middle, and bottom and use the narrowest measurement. Measure the opening height from floor to lintel. Check the headroom above the lintel (the space between the lintel and the garage ceiling), which must be at least 300mm for a standard up-and-over door. Check the available sideroom on each side of the opening (minimum 100mm for standard track brackets). Confirm these measurements are compatible with the door you are ordering before purchasing.

Installing the Frame

Most up-and-over doors come with a steel sub-frame that is bolted to the masonry around the opening. Position the frame in the opening, check for plumb and level, pack behind the frame at fixing points to ensure it sits square, and fix to the masonry using appropriate wall plugs and screws. The frame must be square and level: a distorted frame causes the door to bind and operate poorly.

Fitting the Door Panel and Mechanism

Attach the spring mechanism arms or torsion spring components to the frame at the positions specified in the manufacturer's instructions. With assistance from a second person, hang the door panel in the frame by engaging the retractable or canopy mechanism arms. Follow the manufacturer's sequence carefully; fitting components in the wrong order can create spring tension issues that are difficult to reverse safely.

Spring Tension and Balancing

Spring tension is the most critical and safety-sensitive part of garage door fitting. The spring must be tensioned to balance the door weight so the door stays open at any position without falling. An over-tensioned spring lifts the door aggressively; an under-tensioned spring allows it to fall. Follow the manufacturer's tensioning procedure exactly. If in doubt, have the spring tensioning checked by a qualified garage door engineer after fitting.

Fitting Seals and Final Adjustments

Fit the perimeter seals (bottom, sides, and top) and adjust the lock to align with the frame keep. Test the door through the full open and close cycle, checking that it moves freely and that the spring holds it at the fully open position. Adjust track alignment if the door binds or rubs at any point.

Summary

Fitting an up-and-over garage door requires accurate measurement of the opening, a level and plumb frame installation, careful fitting of the mechanism following the manufacturer's sequence, correct spring tensioning for door balance, and fitting of seals and final adjustments. Spring tensioning is the safety-critical step; follow manufacturer instructions exactly or use professional assistance for this step.