Measuring for an initial quote—not a manufacturing order

Say what the number represents

An opening size, frame size and glass size are not interchangeable. For the initial quote, follow the guidance in the selected product’s Size step and use millimetres. Explain whether you measured the existing frame or the surrounding opening, and whether the height includes the cill.

Keep a simple record

Label each opening by room and keep width and height in a consistent order. A photograph or sketch can show which item each measurement belongs to. Approximate dimensions can start a conversation, but should be labelled approximate.

• Record overall width and height, not one pane.
• Identify the viewpoint on an opening sketch.
• Note uncertain measurements rather than guessing.
• Keep quantities and room labels with each item.

Some products use different conventions

The vertical sliding sash journey asks for the structural opening and shows a proposed quotation size after a 10 mm deduction in each direction. Rooflights and lanterns use their own measurement guidance. Do not apply one product’s deduction or sizing convention to another.

Stop before treating it as an order size

The final survey and manufacturing dimensions need checking before an order. Dolly’s illustration and quotation tool are not a replacement for your installer’s measurements or installation instructions. If the opening is unusual, keep the information and ask for manual review rather than forcing it into a standard layout.