Steel Frame Sizing Checklist: Measure Right Before You Order

Why Sizing Comes Before Everything Else

A custom steel frame is made to the dimensions you give us, so the accuracy of those dimensions decides how well it fits. Small errors in an opening can mean a frame that does not sit square, a gap that needs filler, or a part that has to be remade. Taking time to size properly at the start saves time for everyone involved.

Measure the actual opening on site, not only the drawing. Walls are rarely perfectly straight, and older buildings often vary from one side to the other. Record what you find, even when it differs from the plan.

Measure the Opening Correctly

Take width and height at three points each: top, middle and bottom for height, and left, centre and right for width. Use the smallest figure where the opening narrows. Check the diagonals as well, since a large difference between them shows the opening is out of square.

• Note the wall thickness at each side.
• Record the depth of any recess or reveal.
• Mark the level of the floor or threshold.

Check Fixing Points and Structure

Decide how the frame will be fixed before the dimensions are final. Frames can be anchored into concrete, brick or existing steel, and each method needs room for anchors, plates or welds. Tell us what the wall is made of and where the fixings are planned.

Note nearby services such as pipes, cables and drainage, as well as any existing railings or fittings that the new frame must clear. Our engineer can advise on the fixing method, but exact load values are confirmed with a qualified engineer for your project.

Allow for Finishing and Installation

Finishing changes the final size. Hot-dip galvanizing and powder coating add a layer to the surface, and this should be considered when you set the gap around the frame. Plan the clearance for installation as well, so the frame can be lifted into place and levelled without forcing it.

Tell us which finish you want early, because it affects the tolerances we work to during fabrication.

Confirm Drawings and Written Specification

Once measurements are taken, we prepare a drawing and a written specification showing the frame size, profiles, fixing details and finish. Read both carefully. Check that every dimension matches your site notes and that nothing is missing, such as a door swing or an access path.

Approve the drawing in writing only when you are satisfied. Production starts from the approved version, so any later change may need a revised drawing.

Final Checklist Before You Order

• Opening width and height measured at three points
• Diagonals checked for squareness
• Wall material and fixing method confirmed
• Services and obstructions noted
• Finish chosen and clearance allowed
• Drawing and specification reviewed and approved

Working through this list before you place the order gives the cleanest route from measurement to installation.

Frequently asked questions

Should I measure the drawing or the actual opening?

Always measure the actual opening on site. Drawings can differ from the built wall, and the frame must fit what is really there.

Why do I need to measure the diagonals?

Comparing the two diagonals shows whether the opening is square. A large difference means the frame may need adjustment or a note on the drawing.

Do I need to include the finish in my measurements?

Yes, tell us the finish early, because coatings affect the final size and the clearance needed for installation.

Can the drawing be changed after I approve it?

Changes after approval may require a revised drawing before production continues, so review everything carefully first.

Common mistakes to avoid

The most common mistake is measuring only once and at one point, which misses wall variations that cause fit problems. Another is ordering before the fixing method and finish are decided.

Our recommendation

Measure at three points, note the wall material and any obstructions, and send photos with your dimensions so we can check them before production begins.

Summary

A careful sizing checklist covers opening measurements, squareness, fixings, obstructions, finish allowance and drawing approval. Completing it before ordering helps your custom steel frame fit correctly the first time.

Related guides

• Choosing a Steel Finish: Paint, Powder Coat or Galvanized
• Delivery Planning and Site Access for Steel Orders
• Steel Frame Change Orders: How to Modify During Production
• Custom Steel Frame Warranty and Guarantee: What to Ask
• Acceptance Inspection Checklist for Delivered Steel Frames
• Payment Milestones and Contract Terms for Steel Projects
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