How to Measure Your Garage Opening for a New Door
Ensuring you have the correct measurements for your new garage door is essential for a smooth installation. Whether you’re a homeowner looking to upgrade your garage or a contractor assisting a client, accurate measurements prevent costly errors and ensure a perfect fit. While the basic measuring process applies to all garage doors, different styles – such as sectional, roller or up-and-over doors – may have specific requirements that should be considered before purchase.
In this article, we will explain not only the standard procedure for ensuring precise measurements when sizing up your garage opening for a new door, but also look at a range of additional considerations.
Tools You Will Need
Before you begin, gather a steel tape measure, a notepad and pen to record your measurements and a spirit level to check the straightness of the surfaces. If your garage door opening is particularly tall, you may also need a ladder to reach higher points. For added precision, having a helper can be useful, especially when measuring wider openings.
Step 1 – Measure the Width of the Opening
The width of the garage opening is the most crucial measurement, as it determines the overall size of the door. Using your tape measure, check the distance between the left and right sides of the opening at the top, middle, and bottom. If there are variations between these measurements, record the smallest value as this will reflect the tightest fit.
The type of garage door you choose may influence how width measurements are used. Sectional and roller doors, for example, require a precise fit within the frame, whereas up-and-over and bi-fold doors may need slightly more clearance on the sides for their pivoting mechanism. If the walls are uneven, some adjustments may be necessary during installation.
Step 2 – Measure the Height of the Opening
Next, measure the height from the floor to the top of the garage door opening, again checking at multiple points along the width. If there is any variation, record the shortest measurement to ensure the door can close properly.
For roller garage doors, height is particularly important, as these doors retract into a compact roll above the opening. If the ceiling is lower than expected, you may need a reduced-size roller housing. Similarly, side-hinged doors require careful height consideration, as too much variation in the opening may result in uneven door movement. The same considerations could also be applied when measuring for automatic and electric garage doors which may require additional headroom for any accompanying mechanisms.
Step 3 – Measure the Side Room (Clearance)
The space on either side of the garage opening is referred to as the clearance and is crucial for fitting the tracks or side brackets of your chosen door. Measure from the edge of the opening to the nearest wall on both sides. Most standard garage doors require at least 90mm (3.5 inches) on each side.
Different door types may have varying side clearance requirements. For example, roller doors generally need more side room to accommodate the barrel mechanism and curtain roll, typically 90-120mm per side. Sectional doors require side room for vertical tracks, usually 85-100mm. Up-and-over canopy doors may need less side clearance but require more headroom.
Step 4 – Measure the Headroom
The headroom is the space between the top of the garage opening and the ceiling, which is essential for the door mechanism. Unlike standard doors, garage doors must leave sufficient overhead clearance to accommodate their opening action and hardware components. Standard sectional doors typically require 300mm (12 inches) of headroom for a track system, though some models offer compact tracks for garages with limited overhead space. If your headroom is restricted, special low-clearance options may be available.
Step 5 – Measure the Backroom (Depth)
The backroom, or depth, is the distance from the garage opening to the rear wall. This determines whether the garage has enough space for the door to retract when opened. To measure, start at the garage opening and extend the tape measure to the nearest obstruction, such as a wall, shelving unit, or ceiling beam.
A sectional door typically requires the door height plus 350mm (14 inches) for full retraction. Roller doors require extra space for the rolled-up curtain, while side-hinged doors do not need as much backroom since they open outward. If space is tight, alternative door configurations may be necessary.
Step 6 – Check for Obstructions
Before finalising your measurements, inspect the garage for any obstructions that could interfere with the installation. Look for pipes, ductwork, or shelving near the ceiling, as these could block the track or roller housing. Ensure light fixtures and electrical boxes are not in the way and check if the floor is level, as an uneven surface may require additional adjustments during installation. For garages with tight spaces, a professional assessment or site survey from an experienced garage door installation contractor can help determine the most suitable door style.
Conclusion
When measuring for a new garage door, always double-check your measurements before placing an order. If the opening is irregular, custom-fit solutions may be required. Additionally, consider the door material when finalising your choice – steel and aluminium doors typically have standard fitting requirements, while wooden doors may need extra clearance due to swelling in different weather conditions.
If you are unsure about any measurements or want professional guidance, our team at WM Garage Doors is here to help. Our expert team can assess your garage and recommend the best solution based on your space, style preferences and budget. Contact us today to discuss your options and ensure a perfect fit for your new garage door.