Root face: meaning and how to check it
A root face, also called a land, is the short flat strip left on the edge of a member at the bottom of a bevel or J preparation. Rather than grinding to a knife edge, the fitter leaves a small square edge. It gives the root pass something to fuse into without burning straight through.
Use this diagram
How to recognise and check a root face
- Look at the edge, not the gap. The root face is on the member. Run your eye down the bevel: where the slope stops and the edge turns square, that square strip is the land.
- Measure its height. Measure the flat strip from the bottom of the bevel to the bottom surface of the plate. A small rule, a fit-up gauge or a caliper works.
- Check along the joint. Hand-ground bevels vary. A land that's thick in one spot and thin in another will weld unevenly.
- Compare with the WPS. The joint detail or WPS sets the root face. Use the documents, not your eye, to decide whether it's right.
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Definitions and Terminology
A fatigue crack in a cyclically loaded fillet-welded attachment started along the line where the surface of the weld blends into the flange plate. At which weld feature did the crack start?
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Common mix-ups
- Root face versus root opening. The face is a dimension of the edge. The opening is the gap between two edges. A joint can have a land and no gap, or a gap and no land.
- Too much land. A thick root face holds back fusion, and the root may not penetrate through. That shows up as incomplete penetration on the far side.
- Too little land. A knife edge melts away fast, which invites burn-through or a sagging root, especially with a wide opening.
- Land versus backing. A root face is part of the plate. Backing is a separate strip placed under the joint. Some joints use both.
- The bevel above it. The land is measured below the bevel. The bevel itself has its own angle, covered on the bevel angle vs groove angle page.
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Root face on the CWI exam
Root face and land are in Definitions and Terminology, at least 12% of Part A, which is closed book. The groove weld symbol doesn't show the land directly; it comes from a joint detail or the WPS, which makes it a common trap.
On Part B, joint details live in the procedure documents you're handed. Procedure and Performance Qualifications is at least 28% of the practical, and reading a WPS joint detail, land included, is the kind of check that domain is built on.
On a D1.1 Part C, root faces appear in the prequalified joint details in Clause 5. Use your own copy for the dimensions.
Practice it
The CWI Part A flashcards have a card on where the root opening and groove angle go on a groove symbol. The land is the dimension that card leaves to the joint detail. The welding terms glossary has every joint-prep term in one table.
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Sources
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- AWS bookstore, terminology and symbols listing, American Welding Society. Retrieved 20 Oct 2026.
- CWI Part A Fundamentals Examination Information, American Welding Society, Rev. 03.01.2024. Retrieved 20 Oct 2026.
- AWS B5.1:2025, Specification for the Qualification of Welding Inspectors, American Welding Society, Tables 5.1 and 8.1. Retrieved 20 Oct 2026.
Facts checked 25 October 2026 against the sources listed above. If something has changed, tell us and we will correct it within 2 business days.
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