Aluminum Curtain Wall Site Survey: Checklist for Retrofits

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An aluminum curtain wall site survey records the exact opening dimensions, the condition and make-up of the existing structure, access conditions and finishing requirements before any drawing is issued. Accurate on-site measurement, documented with photos and a written specification, is what allows the factory to produce a unit that fits the building on the first attempt.

Why the Site Survey Comes First

In curtain wall retrofits, the existing building is rarely perfectly square, level or consistent from floor to floor. Openings that look identical on the original drawings often differ by several centimeters once measured. A thorough survey protects the design intent and avoids costly rework after production has started.

Treat the survey as the foundation of the whole process. Every later stage, from the drawing to the finish and installation, depends on the data collected here, so it is worth doing slowly and carefully.

Measuring Openings Correctly

Measure each opening at several points: top, middle and bottom for width, and left, centre and right for height. Record the smallest and largest values, since these reveal how far the opening deviates from square. Check diagonals as well, because a large difference between them signals distortion.

Clear opening width and height at three points each
Diagonal measurements for squareness
Depth of reveal and wall thickness
Sill, head and jamb conditions

Checking the Existing Structure

Note the material and condition of the surrounding structure, including concrete edges, masonry, steel frames and any existing anchors. Look for cracks, spalling, moisture staining and signs of previous repairs. Where loads will be transferred to the structure, the design engineer should confirm the fixing points and capacity before drawings are finalized.

Record the location of any services such as pipes, cables and drainage that could interfere with the new frame or its fixings.

Documenting Access, Site Conditions and Logistics

Retrofit work often takes place in occupied buildings, so access matters as much as dimensions. Document floor levels, lift sizes, stair widths, the route for carrying long profiles and any restrictions on working hours. Note where crane or hoist access is possible and whether scaffolding or a working platform will be needed.

Photograph each elevation and the approach routes. Clear photos reduce misunderstandings later and help the installation team plan.

From Survey to Drawing and Specification

Once measurements are complete, the survey data is transferred into a dimensioned drawing and a written specification. The specification should list the frame system, glazing type, infill panels, opening types, colour and finish. Any tolerances agreed with the architect should be stated clearly.

Share the drawing with the architect or designer for approval before production begins. Written approval protects both the client and the fabricator.

Production, Finishing and Installation Planning

After approval, units are produced in the factory to the measured dimensions. Surface finish, whether powder coating or another system, should be chosen with the building's exposure and maintenance expectations in mind. Confirm the finish sample with the designer before the full run.

Installation planning should follow the survey: fixing method, sequencing by floor, protection of finished surfaces and the sealing details at the perimeter. Coordinating these steps early keeps the retrofit on schedule.

Frequently asked questions

How many measurements should be taken for each opening?

Take at least three width and three height readings, plus both diagonals, to capture any deviation from square. Record the smallest and largest values for the drawing.

Should the survey be done before the design is finalized?

Yes. Survey data should inform the design so that the proposed frames suit the real openings. Designing from original drawings alone often leads to changes later.

Who checks the structural fixing points?

The design engineer should confirm the fixing points and load capacity of the existing structure. The fabricator records the site conditions that the engineer needs to assess.

What information should I send a manufacturer first?

Send photos of each elevation, a sketch with approximate dimensions, the building's floor count and access conditions. Detailed on-site measurement usually follows once the inquiry is reviewed.

Common mistakes to avoid

The most common error is relying on original drawings instead of measuring the building as it stands today. Single measurements that ignore deviation from square also lead to frames that do not fit.

Our recommendation

Measure every opening at multiple points, record diagonals, and photograph the surroundings before drafting anything. Confirm structural fixings with the engineer prior to issuing the final drawing.

Summary

A careful site survey with accurate measurements, structural checks and documented access is the key to a successful aluminum curtain wall retrofit.

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