A hatch pattern is the repeating fill that tells you what material a cut element is made of. Concrete reads as stipple with small triangles, brick and general masonry as 45 degree diagonal lines, earth as clusters of short lines, and batt insulation as a looping wavy line. The project's G-sheet legend overrides any convention.
Last reviewed October 2026
Helonic, an AI drawing review platform, reads material callouts, wall types, and rating marks across a PDF set, and those are the same things a hatch is supposed to agree with. The table below describes each common hatch in words, since the patterns themselves vary by office.
These are the patterns you'll meet most often in building and wall sections. The AutoCAD names are the standard patterns that ship with the program, listed where offices commonly use them.
| Material | How it's drawn in section | Common AutoCAD pattern |
|---|---|---|
| Concrete | Random dots with small scattered triangles for the aggregate | AR-CONC |
| Concrete masonry (CMU) | Diagonal lines through the face shells with the cells drawn open; grouted cells filled with the concrete stipple | ANSI31 for the shells, AR-CONC for grout; AR-B816 for block in elevation |
| Brick (common) | Evenly spaced 45 degree diagonal lines; in elevation, coursing with mortar joints | ANSI31 in section; AR-BRSTD in elevation |
| Earth (undisturbed soil) | Clusters of short parallel lines set at alternating angles, often only in a band along the soil edge | EARTH |
| Compacted or engineered fill | No single convention; often the earth pattern with dots or a hatch defined in the legend | Office legend |
| Gravel | Small random stones or polygons | GRAVEL |
| Sand | Fine random dots with no triangles | AR-SAND |
| Batt insulation | A continuous looping or wavy line filling the cavity | Usually the BATTING linetype or a block, not a hatch |
| Rigid insulation | Crosshatch (diagonal X lines) or a tight zigzag between two lines | ANSI37 or an office crosshatch; AutoCAD also ships INSUL |
| Rough or framing lumber | One X drawn corner to corner across each cut member | Drawn as lines, not a fill |
| Blocking and shims | A single diagonal line corner to corner | Drawn as lines |
| Finished wood | Curved grain lines along the piece | Office pattern |
| Plywood | Thin layered lines showing the plies; at small scale, an outline with the panel thickness | Office pattern |
| Steel | Solid fill at small scale; pairs of close diagonal lines at large scale | SOLID or ANSI32 |
| Aluminum | A light diagonal pattern kept distinct from steel, or just the extrusion outline at small scale | ANSI38 |
| Glass | One or two thin lines in section; no fill at most scales | None |
| Gypsum board | Two thin lines, sometimes with a fine dot fill between them | Often none, or a fine stipple |
| Stone | Irregular diagonal lines or random veining | ANSI36 (marble, slate) |
| Membranes and barriers | A heavy line or a dashed line along the face it covers | A linetype, not a hatch |
Use this table to read an unfamiliar set, then check the set against its own legend. Two offices can draw rigid insulation two different ways and both be correct, as long as each set's legend says so.
Office standards set hatches, and building codes say nothing about them. The Uniform Drawing System in the National CAD Standard includes material symbols, but firms adopt it to different degrees and add their own. Revit families and AutoCAD templates carry each firm's choices from project to project.
The ANSI patterns in AutoCAD show how loose the mapping is. They come from mechanical drafting, where ANSI31 means iron, ANSI32 means steel, and ANSI38 means aluminum. Architects borrowed ANSI31 for brick and masonry because it was there. So the only reliable key is the material legend in the set you're holding, usually on the general sheets with the architectural plan symbols and abbreviations.
If there's no legend, read the material callout or keynote next to the hatch. A leader that says "rigid insulation" tells you more than the fill does.
The same material is drawn differently depending on the view. Brick is the clearest example: in section it's diagonal lines, and in elevation it's drawn as coursing with mortar joints, because you're looking at its face.
Scale changes things too. At 1/8" = 1'-0" a wall may be two lines with a gray fill. At 3" = 1'-0" on a wall section, every layer gets its own hatch. Wall sections and building sections are compared in building section vs wall section.
A hatch is a claim about material. When it disagrees with the note beside it or the wall type it belongs to, one of them is wrong, and the field will build whichever one they read first.
On each wall section, read the layers from outside to inside and name each hatch out loud. If you can't name one from the legend or a callout, it's undefined, and that's an RFI.
This check belongs in the envelope and life safety part of a full review. The order for the rest of the set is in how to review construction drawings.
Helonic reads the wall type schedule, the floor plans, the wall sections, and the life safety plan together. It flags a wall tagged as rated on one sheet and unrated on another, and material callouts that disagree between a section and its detail. Fire and life safety checks and envelope analysis cite the sheet for each finding.
The architect decides what the assembly should be. If you're still learning the set itself, start with how to read blueprints.
Practitioner insight
“The wall section had the rigid board hatched, the leader said mineral wool, and the spec said polyiso. Three answers on one wall. The hatch was just whatever was in the template.”
Conversations with envelope consultants reviewing architectural wall sections during design development and CD review.
Manas is the co-founder and CTO of Helonic, where he leads engineering and AI research for construction drawing analysis. He works directly with structural, MEP, civil, and fire protection engineers to translate the way they review drawings into AI systems that flag the issues that actually matter in the field. Before Helonic, he built machine learning pipelines for technical document understanding and has spent the last several years interviewing licensed design engineers and discipline leads to ground product decisions in real practice rather than industry assumptions.
How this page was researched: AutoCAD pattern names are from the standard patterns that ship with AutoCAD, including the ANSI series that comes from mechanical drafting. Material conventions vary by office and by template, so the article describes common practice and defers to each project's legend.
Last reviewed by Manas Gandhi · October 2026
Related references for reading sections, legends, and assemblies.
The other half of the legend: symbols, tags, and marks.
Where the insulation and rating on a wall are defined.
Rated assemblies and how they're shown in the set.
The views where you'll read most hatches.
The full reading order for a drawing set.
A systematic approach to catching drawing errors before construction.