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Custom size exterior doors solve openings that do not suit a standard catalogue unit, but “custom size” needs more than a width and height. The useful specification distinguishes the door leaf from the frame, the complete unit from the finished opening, and the finished opening from the structural opening. If those terms are mixed, even an accurate number can be applied to the wrong part of the build.
The goal at enquiry stage is not to produce a final fabrication drawing. It is to give the door maker enough labelled information to identify the configuration, recognise site risks and ask the right follow-up questions.
Record the complete opening, not one convenient measurement
Measure width and height at more than one point and note whether the values describe an existing frame, a finished opening or exposed structure. Record wall or jamb depth, threshold and floor transitions, nearby trim, ceiling or arch details, and the clear space available for swing. Photographs from inside, outside and across the threshold often reveal conditions that numbers alone miss.
For replacement work, do not assume the old slab size defines the new unit. Existing frames can be out of square, partly concealed or built differently from the proposed package. Use our fuller door measurement guide to label each dimension consistently.
Let configuration and installation guide the final size
A single leaf, double entry, sidelight or transom package distributes the available width and height differently. Frame members, clearances, weather details and hardware preparation occupy space too. The installer and manufacturer therefore need to agree which party is responsible for converting site measurements into the final unit size.
Share the intended handing, opening direction, access constraints and delivery destination early. Large framed units may need to be divided for handling, and the route from unloading point to opening can be as important as the facade measurement.
Build a brief that can be checked
A useful first submission contains approximate labelled dimensions, opening photographs, preferred material and configuration, design references and known glass or hardware needs. YMSCollections can then clarify what is included and what still requires confirmation. Browse the custom entry door planning guide for the wider decision sequence, or review a custom front door and frame project for context.
Use the custom door brief to send dimensions, photographs or drawings. Final site dimensions and installation tolerances should always be confirmed by the responsible project professionals before production approval.
Explore the product direction: browse the exterior door collection and use the custom door brief to ask which designs can be adapted to your dimensions.
