A window order needs more than a width and height. Distinguish field measurements, design dimensions, product dimensions and required installation clearances; coordinate support and enclosure interfaces; and identify who verifies each input. Shop drawings translate the chosen system into the project, while review and approval responsibilities must remain explicit.
Canadian planning context. Technical examples from other regions are identified in the guide; approval and performance requirements must be checked for the actual building and jurisdiction. Original explanatory diagrams are not construction details.
- An opening dimension, frame dimension and visible-glass dimension are different.
- Identify the datum, units, measurement method and access limits for every survey.
- Manufacturer clearances and project tolerances must be coordinated rather than guessed.
- Sections reveal interfaces that an elevation or BIM object can hide.
- Record revisions and field changes before fabrication or concealment.
01 /Define the information chain and responsibility
The homeowner’s inventory identifies an opening and its concerns. A designer’s survey establishes the existing geometry and interfaces. A supplier’s order translates those inputs into product dimensions. Shop drawings coordinate fabrication and installation with the project. These documents are related, but they have different purposes and levels of certainty.
Before the survey, decide who measures, who checks the receiving structure, who confirms product clearances and who authorises fabrication. A contractor taking a measurement does not automatically accept responsibility for the structural design. A consultant reviewing shop drawings does not necessarily verify every field dimension. Those obligations need to be stated in the project’s agreements and review process.
Use the homeowner measurement brief for early information collection and the specification schedule guide for product and procurement requirements. This guide addresses the subsequent coordination between surveyed conditions, designed interfaces and fabrication documents.
02 /Choose datums, units and opening identifiers
A datum is the reference from which a dimension is taken. State whether height is measured from structural floor, finished floor, an exterior sill or another defined level. For repeated openings, a consistent reference helps distinguish a genuinely different opening from a different measurement convention. Show the reference on drawings rather than leaving it in a technician’s notebook.
Use one unit convention and identify any conversion. Avoid mixing millimetres, centimetres, inches and nominal catalogue sizes without labels. Rounding can matter when several components and clearances accumulate. Keep raw measured values separate from the dimensions selected for ordering; the latter may include coordinated allowances and design decisions.
Link every measurement to an opening identifier, photograph, date and surveyor. Where the opening is inaccessible or concealed by trim, mark the limitation. A preliminary dimension taken through an existing frame should not silently become a verified rough-opening dimension. Define which items require remeasurement after planned opening-up.
03 /Survey geometry and the receiving surfaces
| Input | Why it matters | Record |
|---|---|---|
| Opening geometry | Out-of-square, bow and local variations affect fit | Multiple dimensions and method |
| Receiving material | Anchors and support require a suitable substrate | Material, condition and access limits |
| Wall depth | Frame placement, lining and control-layer connections | Sections through representative locations |
| Sill and head | Support, slope, drainage and clearance | Levels and existing concealed-condition findings |
| Adjacent finishes | Trim, cladding, screens and access | Photographs and coordinated details |
| Delivery route | Large products require suitable handling access | Site constraints and lifting assumptions |
Existing buildings often contain variations. Do not assume that openings on one façade are identical because the elevation repeats. The survey can establish representative groups, but the responsible team should decide which dimensions need individual verification. Keep exceptions visible so the supplier does not fabricate every unit from one convenient sample.
Identify the condition of the substrate separately from its dimensions. A correctly sized opening with decayed timber or damaged concrete still needs a repair and attachment design. If the condition cannot be established before removal, agree on a hold point and a process for resolving findings before the new unit is installed.
04 /Coordinate frame size, rough opening and clearances
A manufacturer may define frame dimensions, nominal size, installation flange size and rough-opening requirements differently from another manufacturer. Read the exact product instructions. Do not subtract a standard allowance from every measured opening or reuse a clearance learned on a different system.
The clearance must accommodate the intended support, fastening, sealing and movement without undermining the product’s installation. Adjacent tolerances matter: structural opening, frame fabrication, placement, cladding and interior lining can each vary. The design team should resolve the combined condition rather than allowing every trade to consume the same small gap.
Show the installation position within the wall. A deeper or shallower frame changes exterior reveals, thermal continuity, air-seal access, sill drainage and interior finishes. “Install centred” may be insufficient where the wall contains several control layers. A coordinated section gives the installer a reference that a plan symbol cannot.
05 /Use shop drawings to expose the interfaces
An elevation should identify units, operation, mullions, glass types and finish. Sections should show head, jamb, sill, joining and significant transitions. For a façade system, include anchors, movement joints, slab edges, corners and spandrels as applicable. Dimension the interfaces enough that the other trades can coordinate their work.
Kawneer’s architectural manuals illustrate product sections, performance information and CAD resources. Andersen’s installation resources provide product-specific preparation and joining guidance. These references inform the selected detail; they do not replace project-specific shop drawings or design.
A downloaded BIM object can support coordination but should not be assumed to contain every necessary connection or the exact quoted configuration. Verify its version, dimensions, operation and level of detail. A clash-free model can still omit a water path, unsuitable anchor or inaccessible service component.
06 /Review structure, enclosure and operation together
The structural review should identify loads, support, anchors, substrate and movement. The enclosure review should identify water drainage, exterior transitions, air-control continuity and thermal effects. The operating review should identify sash paths, handles, screens, safety devices and maintenance access. None should be left to infer its interface from a different discipline’s drawing.
Glass make-up affects weight, thickness and support. A change from one glazing package to another may require changes to stops, blocks, frame construction or hardware. A solar-control substitution can also affect appearance. Use a formal change review rather than treating every glass option as interchangeable within the same frame.
For fire-rated boundaries, guards or other specialised functions, identify the required complete system and the professional responsible for its design. Ordinary window sealant, laminated glass or a stock frame cannot be assumed to meet those functions. Keep the relevant evidence linked to the particular location and assembly.
07 /Manage review comments and fabrication releases
Keep a revision register that states the issue date, changes, reviewer comments and release status. A stamp or email saying “reviewed” can mean different things under different contracts. Establish what review authorises and what remains with the supplier or contractor. Do not fabricate from a superseded drawing because it is the only printed copy on site.
Require unresolved dimensions, substitutions and interfaces to be clearly marked. A drawing can be accepted in part while certain units remain on hold. Separate that status from a general project deadline. Ordering pressure is not evidence that an unverified opening or connection is acceptable.
When field conditions differ, record the finding with photographs and dimensions and obtain the necessary revision. A shortened trim or minor finish change may be routine; a changed support, joint, glass or drainage path can require design review. Define the threshold and communication route before the installer encounters the problem.
08 /Use mock-ups and hold points for concealed work
A representative mock-up can reveal fit, finish, operation and difficult interfaces before repetition. Select a location that contains the relevant conditions rather than the easiest opening. Agree on who reviews it and what must be documented. If performance testing is required, its method and acceptance criteria should be defined separately from appearance approval.
Set inspection points before critical details are concealed: repaired substrate, support and anchors, sill and perimeter transitions, joining and specified seals. Photographs should identify the opening and stage, not simply show an anonymous strip of membrane. A record of concealed work is useful later only when it can be connected to the finished asset.
If a test or inspection finds a problem, preserve the result and the corrective detail. Repeated work should follow the accepted revision. A passed specimen has a defined scope; use it alongside consistent installation inspection rather than calling it proof of every opening’s performance.
09 /Close out with as-installed information
The final archive should reflect what was installed, not merely what was first proposed. Record approved substitutions, site changes, product identifiers, glass make-ups and location-specific variations. Include service access and the components that must be removed for glass replacement. This turns the drawing set into a usable asset record.
Keep care instructions, warranty, test reports and inspection records connected to that archive. Note any outstanding monitoring or deferred work. A final drawing is not a blanket statement that every concealed detail was inspected; the evidence record should state what was actually observed and tested.
For the owner, provide a clear index and a simpler operating and maintenance summary. For the next designer or technician, retain the detailed interfaces. Good coordination reduces ordering mistakes and makes future repair more predictable because the project’s dimensions, assumptions and changes remain visible.
FAQQuestions people ask
Can I order from the visible glass dimensions?
No. Visible glass, frame and rough-opening dimensions describe different things. The supplier must identify the required measurement convention and verify the order against the installation detail.
Does a reviewed shop drawing mean every field dimension was checked?
Not necessarily. Review responsibilities depend on the project agreements. Explicitly identify who verifies dimensions, design, compatibility and release for fabrication.
Is a downloaded BIM object a complete installation detail?
No. Its dimensions, version and configuration must be checked, and it may omit structural, drainage, sealing or service interfaces needed for the project.