Garage door sizing and fitting

A garage door size is not always the size of the hole in the wall. A manufacturer may publish a nominal leaf size, an overall frame size, an ordering size or a clear passage size. These figures answer different questions. A door listed as a certain width is not automatically suitable for an opening of that same width.

Measure four spaces

Record the opening width and height at several points, then note the smallest reliable measurement. Measure headroom from the top of the opening to the lowest ceiling obstruction; side room from each reveal to the nearest obstruction; and garage depth from the opening to the back wall or anything that limits the door’s travel. Also note floor slope, pipes, lights, storage and whether a vehicle will sit beneath tracks.

Use our illustrated measuring guide and keep the left and right side-room figures separate. A single average can hide an obstruction on one side.

Treat manufacturer sizes as model-specific

Garador’s up-and-over sizing table distinguishes nominal sizes between the frame from the overall dimensions of pre-framed canopy and retractable doors. It also specifies extra clearance when fitting between brickwork. Those dimensions describe Garador products and arrangements; they are not a national standard that can be applied to another brand.

Clearance depends on door type and configuration. For example, Garador publishes different sectional-door depth requirements for manual operation and for a GaraMatic operator. Hörmann’s diagrams likewise show different headroom and side-room ranges for different sectional fitting positions. See headroom and side room.

What a survey should confirm

Ask the installer to record the structural opening, the order size, the frame or guide positions, usable passage dimensions, operating clearance, and any building work needed. Confirm whether the quote includes removal and making good, and whether the proposed door can be operated manually if the power fails. Do not order from a rough opening measurement alone.

Use the garage door size checker to organise your measurements. It can only compare the published examples in its data; the manufacturer’s instructions and a site survey decide the final fit.