How to Measure a Steel-Look Window Opening Correctly

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To measure a steel-look window opening, record the width and height at several points inside the frame, use the smallest reading, and note the depth and any obstructions. Take the measurements on the actual opening rather than from the plans, and check them twice before ordering.

Why accurate measurements matter

A Belgian steel-look profile window is made to measure, so the frame is built around the exact opening you give us. Small errors that seem harmless on paper can leave gaps, force the frame to be installed crookedly, or require a costly remake. Careful measuring at the start saves time for everyone involved.

Walls in older buildings are rarely perfectly square, so the numbers you take on site matter far more than any drawing. Treat the opening as it actually is, not as it was originally planned.

Tools you need before you start

Gather a steel measuring tape, a spirit level, a pencil, a notebook and, if possible, a second person to hold the far end of the tape. A laser measure is helpful for long spans but is not essential.

Steel tape measure, at least 5 meters
Spirit level or a long straight edge
Notepad and pencil for a simple sketch
Camera or phone to photograph the opening

Measuring width and height step by step

Measure the width at the top, middle and bottom of the opening, and the height at the left, centre and right. Write down all readings. Use the smallest width and the smallest height as your working dimensions, because the new frame must fit the tightest point.

Measure from the finished inner face of the wall to the opposite face, including any plaster or tile already in place. If the wall is still being finished, note that and plan with your contractor.

Checking depth, plumb and square

Measure the depth of the reveal, which is the distance from the outer face to the inner face of the wall. This affects how the frame sits and how the fixing is made. Check whether the sides and sill are plumb and level with your spirit level.

Measure both diagonals of the opening. If the two diagonal readings differ noticeably, the opening is out of square, and you should tell us so the drawing can account for it.

Noting obstructions and the opening type

Mark anything that could affect the frame: pipes, electrical boxes, shutter housings, air conditioning sleeves, or uneven edges. Note whether the window will open inward or outward and which way the handle should face.

Describe the opening type, for example a single casement, a sliding unit, or a fixed pane, and whether it is a window or a balcony door. Photos from several angles help us understand the situation before a visit.

Sending your measurements to the factory

Send us your sketch with all readings marked, along with clear photos of the opening and the surrounding wall. Include the floor level if it is a door, and any notes about the wall finish. Our team reviews the details, arranges an on-site measurement when needed, and prepares a drawing and written specification for your approval before production starts.

Nothing is manufactured until you have approved the drawing, so you have a chance to correct any detail first.

Frequently asked questions

Should I measure the rough opening or the finished one?

Measure the opening as it will be once the plaster or tiles are finished, since that is where the frame will sit. If finishing work is still ahead, tell us so the dimensions can be coordinated.

What if my opening is not square?

That is common in older buildings and it is not a problem by itself. Record the diagonals and the differences in width and height, and we will account for them in the drawing.

Do I need to measure twice?

Yes, it is a good habit. Taking two independent sets of readings helps catch reading or writing errors before they reach the production stage.

Can I send only photos instead of measurements?

Photos help us understand the opening, but they cannot replace measured dimensions. We recommend sending both, and we can arrange an on-site measurement when precision is critical.

Common mistakes to avoid

The most common mistake is measuring only once in one spot and using the nominal size from a plan. Always measure at several points on the actual opening and use the smallest reading.

Our recommendation

Measure at three heights and three widths, write every reading down, and send photos with your sketch. When in doubt, let us measure on site before anything is ordered.

Summary

Measure width, height, depth and diagonals at several points, use the smallest working dimensions, note obstructions, and send everything with photos before ordering.

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