Walls — Create and edit walls (types, constraints, joins) - Autodesk Revit

SECTION 1

Historical Context & Motivation

Before the rise of Building Information Modeling (BIM), architects and designers represented walls as simple pairs of parallel lines on a two-dimensional drafting board. Those lines carried no material data, no height constraints, and no intelligence about how they connected at corners or intersections. Every change in wall thickness or composition required manual redrawing of plans, sections, and details—a labor-intensive process prone to coordination errors. The transition from CAD linework to parametric, data-rich wall objects in Revit represents one of the most consequential shifts in architectural production since the adoption of computer-aided drafting itself.

1963 • Sutherland's Sketchpad

Ivan Sutherland demonstrates the first interactive computer graphics system at MIT, introducing the concept of parametric constraints—objects that 'remember' their geometric relationships—laying the intellectual groundwork for all future BIM tools.

1982 • AutoCAD Launches

Autodesk releases AutoCAD, making digital drafting accessible on personal computers. Walls are represented as dumb geometry—lines and hatches—with no embedded material or structural information.

1997 • Revit Technology Corporation Founded

Leonid Raiz and Irwin Jungreis establish the company that will create Revit, envisioning a fully parametric building modeler where every element—including walls—carries data about its composition, constraints, and relationships.

2002 • Autodesk Acquires Revit

Autodesk acquires Revit and begins integrating BIM into mainstream practice. The wall element becomes the paradigmatic example of an intelligent building component—editable through types, constrained by levels, and automatically joined at intersections.

2020s • Cloud BIM & Generative Design

Modern Revit versions incorporate cloud collaboration, real-time co-authoring, and generative design tools that leverage the parametric wall system for performance analysis and sustainability optimization.

Understanding walls in Revit is not merely about placing geometry—it is about working within a parametric system where every wall element encodes material layers, structural behavior, fire-rating data, and spatial relationships. How does a single wall object simultaneously serve as a drawing element, a material schedule contributor, and a spatial boundary? That is the question this lesson addresses.

SECTION 2

Core Principles & Definitions

Revit walls operate on a set of interconnected principles that distinguish them from simple geometric extrusions. Every wall instance in a project is governed by a wall type (defining its internal composition), a pair of vertical constraints (controlling its height and attachment to levels), and a set of join conditions (determining how walls merge or separate at intersections). Grasping these three dimensions of wall behavior is essential before placing your first wall element.

Wall Types & Families

Walls belong to three system families—Basic Wall, Curtain Wall, and Stacked Wall. Each type is defined by its internal layer structure, which you edit in the Type Properties dialog.

Vertical Constraints

Every wall has a Base Constraint and a Top Constraint tied to project levels or set as an unconnected height. Constraints allow walls to automatically resize when floor-to-floor heights change.

Wall Joins

When walls meet, Revit automatically resolves their geometry through join conditions—butt, miter, or square off—which can be overridden manually to control visual output in plan views.

Location Line

The Location Line determines which reference within the wall's thickness (Wall Centerline, Core Centerline, Finish Face Interior/Exterior, Core Face Interior/Exterior) Revit uses for placement and dimensioning.

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KEY TAKEAWAY

Think of a Revit wall like a smart sandwich: the wall type defines the recipe (bread, lettuce, cheese—or in our case, gypsum board, studs, insulation, sheathing). The constraints tell the sandwich how tall to grow if the plate changes size. And the joins determine how two sandwiches stack or merge when they meet at a corner. Unlike a CAD line, the wall 'knows' what it is made of and how it relates to its neighbors.

SECTION 3

Visual Explanation — Wall Anatomy

A plan-section view through a typical exterior wall type showing all five layer functions (Finish, Substrate, Core Boundary, Structure, and Thermal/Air). The dashed lines indicate the Wall Centerline and Core Centerline location line options.

The diagram above reveals how Revit organizes wall composition into functional layers arranged symmetrically around a core boundary. The core boundary is a non-physical marker that separates structural layers from finish layers; it plays a critical role in how Revit resolves wall joins and in how room-bounding calculations work. When you select a Location Line of 'Core Face – Exterior,' for example, Revit places the wall so that the outer edge of the structural core aligns with your drawn path, and the finish layers extend beyond it. This distinction is essential in coordinated practice because structural engineers typically dimension to core faces while architects may reference finished surfaces.

SECTION 4

How It Works — Wall Creation & Constraint Logic

Placing a Wall

Wall placement begins on the Architecture tab → Build panel → Wall command (keyboard shortcut WA). Upon activation, the Options Bar and Properties palette expose the essential parameters: wall type, height or top constraint, location line, chain mode, and offset. You draw walls by clicking start and end points in a plan view, and Revit generates a three-dimensional solid governed by the selected type's layer structure and the specified vertical constraints.

Vertical Constraint System

The Base Constraint locks the bottom of the wall to a specific level, with an optional Base Offset (positive pushes the base up, negative pushes it down from the level). The Top Constraint can be set to either 'Up to Level' (linking to another level, with an optional Top Offset) or 'Unconnected' (specifying a fixed height value). When a wall is constrained between two levels and you change a level's elevation, the wall stretches or shrinks automatically—a defining advantage of parametric modeling over static CAD geometry.

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Constraint Best Practice

Always constrain walls to levels rather than using 'Unconnected' height whenever possible. Level-constrained walls automatically update when floor-to-floor heights change during design development, reducing rework and preventing coordination errors between plans and sections.

Wall Join Behavior

When two walls meet or cross, Revit invokes the Wall Joins engine. The default behavior is an automatic join that merges like layers—core to core, finish to finish—at corners, L-junctions, and T-junctions. Three explicit join configurations exist. A butt join terminates one wall against the face of another without merging. A miter join creates a diagonal seam at 45° (or the bisecting angle for non-perpendicular walls). A square-off join forces each wall end to remain a clean right-angle cut. You toggle between these using the Modify → Wall Joins tool, or by right-clicking a wall end grip and selecting 'Disallow Join' to prevent Revit from auto-joining altogether.

SECTION 5

Detailed Breakdown — Wall Type Classification

Revit organizes walls into three distinct system families, each with its own editing paradigm and use case. Unlike loadable families (doors, windows, furniture), wall families cannot be created from external files—they are embedded in the Revit application and configured exclusively through the Type Properties dialog. Understanding when to use each family is fundamental to building an accurate and efficient model.

Plan-view comparison of the three join conditions. Butt joins terminate one wall against another's face. Miter joins merge layers at a diagonal seam. Square-off joins force both walls to maintain clean perpendicular ends.

System Family	Description	Typical Use Cases
Basic Wall	A layered construction defined by material functions (Finish, Substrate, Core Boundary, Structure, Thermal/Air). Layers are edited in the Edit Assembly dialog.	Interior partitions, exterior enclosures, foundation walls, retaining walls. The workhorse of most projects.
Curtain Wall	A grid-based system subdivided by curtain grids into panels and mullions. Does not use the layer structure model.	Glass façades, storefronts, custom panel systems. Allows embedded doors and operable panels.
Stacked Wall	Combines two or more Basic Wall types vertically. Each sub-wall has its own height and type, but they move as a single element.	Walls that change construction at a specific elevation—e.g., masonry below with metal panel above.

Revit wall system families and their applications

Within the Basic Wall family, each wall type defines its layers through the Edit Assembly dialog. Every layer receives a Function (Structure, Substrate, Thermal/Air Layer, Finish 1, or Finish 2), a Material, and a Thickness. The layer function is not merely cosmetic—it governs how Revit wraps layers at inserts (doors and windows), how room boundaries are calculated, and how layers merge at wall joins. Structure-function layers, for instance, always wrap around inserts to maintain structural continuity, while finish layers may or may not wrap depending on the wrapping settings you configure.

SECTION 6

Worked Example — Creating & Constraining an Exterior Wall

Create, Edit, and Join an Exterior Wall Assembly

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Step 1 — Select the Wall Tool & Choose a Type

Open a Level 1 floor plan view. Navigate to Architecture tab → Build panel → Wall (or press WA). In the Properties palette, select 'Basic Wall: Exterior – Brick on CMU' from the Type Selector dropdown. This type is pre-defined in most Revit templates and includes brick veneer, air gap, CMU structure, and interior gypsum board.

Wall tool active with 'Exterior – Brick on CMU' type selected.
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Step 2 — Set Constraints in the Options Bar

In the Options Bar, set Height to 'Level 2' (top constraint linked to the level above). Set Location Line to 'Core Face – Exterior' so that the structural face of the CMU aligns with the grid or reference planes you will snap to. Leave 'Chain' checked to draw continuous wall segments.

Top Constraint = Level 2; Location Line = Core Face – Exterior; Chain = On.
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Step 3 — Draw the Wall Path

Click at point A (e.g., grid intersection 1/A) to begin the wall. Move the cursor horizontally to the right and click at point B (grid intersection 4/A)—a distance of, say, 18 meters. With Chain mode active, click at point C (grid 4/D) to turn a corner. Press Esc to finish. Revit automatically joins the two wall segments at the corner with a miter join (since both walls share the same type).

Two wall segments placed and auto-joined at a 90° miter corner.
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Step 4 — Edit the Wall Type

Select one wall segment. In Properties, click Edit Type → Edit (Assembly). The Edit Assembly dialog opens, showing each layer's Function, Material, and Thickness. To add rigid insulation outboard of the CMU, click 'Insert' to add a new row below the air gap layer. Set Function to 'Thermal/Air Layer,' Material to 'Rigid Insulation,' and Thickness to 50mm. Click OK to apply.

Wall type now includes a 50mm rigid insulation layer. Total wall width has increased accordingly.
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Step 5 — Modify the Corner Join

If the automatic miter join at the corner does not produce the desired plan graphic, navigate to Modify tab → Wall Joins. Click on the corner junction. A dialog appears allowing you to cycle through Butt, Miter, and Square Off. Select Butt to force the shorter wall to terminate against the longer wall's exterior face—useful when one wall wraps a corner and the other meets it perpendicular. Press Esc to exit the tool.

Corner join changed from miter to butt. Plan graphics updated to reflect the new condition.

SECTION 7

Strengths, Limitations & Comparisons

Feature	Strengths	Limitations
Wall Types	Centralized type definitions ensure consistency. Changing a type updates every instance project-wide.	Cannot model complex or non-uniform layer assemblies (e.g., walls that taper in thickness). Requires workarounds with in-place families.
Constraints	Level-linked constraints automate height adjustments, saving time during design iteration and preventing coordination errors.	Walls can only be constrained to horizontal levels—cannot follow sloped references natively (profile editing or curtain wall workarounds needed).
Joins	Automatic layer merging at corners produces clean, constructable details with minimal manual intervention.	Join behavior can be unpredictable with walls of very different types. Overriding joins is manual and can reset if walls are moved.
Location Lines	Six location line options provide precise control over which reference within the wall's thickness is used for placement.	Changing the wall type after placement can shift the wall position if core or overall widths differ from the original type.

Strengths and limitations of Revit's wall system

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KEY TAKEAWAY

Revit walls are extraordinarily powerful for standard construction conditions—rectilinear plans, level-based floor-to-floor heights, and conventional material assemblies. However, as a visual arts student exploring unconventional forms, you will inevitably encounter situations where Revit's wall system resists your design intent. In those cases, think of the system wall as your starting vocabulary and in-place families, adaptive components, and massing tools as your extended vocabulary for freeform enclosure.

SECTION 8

Connection to Advanced Theory — Compound & Profile Editing

Once you are comfortable with standard wall placement, two advanced features extend the system's expressive range. Vertically compound walls allow individual layers to split at specified heights, enabling a wall whose exterior finish changes from brick to metal panel at a certain elevation without resorting to stacked walls. Profile editing allows you to reshape a wall's elevation profile—cutting gable shapes, stepped parapets, or custom silhouettes directly into the wall geometry, which is particularly relevant for sculptural architectural expression.

Concept	Standard Wall Editing	Advanced Techniques
Vertical composition	Uniform layer structure from base to top. Entire wall is one assembly.	Vertically compound walls with split regions, or Stacked Walls combining multiple types at specified heights.
Profile shape	Rectangular extrusion between base and top constraint.	Edit Profile allows freeform elevation outlines—gables, arches, stepped parapets, and irregular silhouettes.
Join complexity	Automatic butt/miter/square joins at endpoints.	Wall sweeps and reveals add molding profiles to wall faces. Embedded curtain walls create glazed openings within basic wall assemblies.
Curvature	Arc-based walls using the Arc draw tool on the Options Bar.	Complex curved walls via conceptual mass surfaces using Wall by Face. Enables double-curved and non-planar enclosures.

Standard vs. advanced wall editing techniques

For students of visual arts and architectural design, the Wall by Face workflow is especially significant. By first creating a freeform mass surface—using Revit's conceptual massing environment or imported geometry from Rhino/Grasshopper—you can apply wall types to those surfaces, inheriting the mass's curvature while retaining the wall's material data and scheduling capabilities. This bridges the gap between sculptural design intent and constructable BIM documentation, a tension that defines much of contemporary computational design practice.

SECTION 9

Practice Problems

Question 1: CONCEPTUAL

Explain the difference between a wall's 'Type' and its 'Instance' properties. Give two examples of each and describe why this distinction matters for project-wide consistency.

Show answer

Type properties are shared by every instance of a given wall type and include the layer structure (assembly), coarse-scale fill pattern, wrapping behavior, and identity data like type name and keynote. Instance properties are unique to each placed wall element and include Base Constraint, Top Constraint, Base Offset, Top Offset, and Location Line. This distinction ensures that when you modify a Type property—say, adding a 25mm insulation layer—every wall of that type in the project updates simultaneously, maintaining consistency across hundreds of wall instances without manual editing.

Question 2: BASIC CALCULATION

A Basic Wall type has the following layers from exterior to interior: Brick (90mm), Air Gap (25mm), Rigid Insulation (50mm), CMU Structure (200mm), Gypsum Board (16mm). What is the total wall thickness? If the Location Line is set to 'Core Face – Exterior,' how far from the placement line does the outermost brick surface extend?

Show answer

The total wall thickness is 90 + 25 + 50 + 200 + 16 = 381mm. The core boundary in this assembly wraps the CMU Structure layer. 'Core Face – Exterior' places the wall so the outer face of the CMU (the core) aligns with the drawn path. The layers outboard of the core are: Rigid Insulation (50mm) + Air Gap (25mm) + Brick (90mm) = 165mm. Therefore, the outermost brick surface extends 165mm beyond the placement line to the exterior side.

Question 3: INTERMEDIATE

You have placed exterior walls constrained from Level 1 (elevation 0.000m) to Level 2 (elevation 3.600m). The client requests the floor-to-floor height increase to 4.200m. Describe what happens to the walls automatically, and explain what additional manual adjustment you might need to make if a parapet wall above Level 2 was placed with an 'Unconnected' height of 1.200m.

Show answer

The exterior walls constrained between Level 1 and Level 2 will automatically stretch from 3.600m to 4.200m when you change Level 2's elevation—this is the core benefit of level-based constraints. However, the parapet wall placed with an 'Unconnected' height of 1.200m is not linked to any level above it. Its base is constrained to Level 2, so its base will move up with Level 2 (maintaining the 1.200m unconnected height above the new Level 2 elevation), but if the design intent was for the parapet to reach a specific absolute elevation, you would need to manually adjust its height. This scenario illustrates why it is best practice to define a 'Roof' or 'Parapet' level and constrain even short walls to named levels rather than using unconnected heights.

Question 4: APPLIED

You are designing a gallery space where a 200mm concrete wall meets a 125mm steel-stud partition at a T-junction. In plan view, the automatic join shows the partition's gypsum board layers merging awkwardly into the concrete wall's mass. Describe the steps you would take to achieve a clean graphic where the partition terminates crisply against the concrete wall without layer merging.

Show answer

First, select the partition wall at the junction end and right-click the end grip, then choose 'Disallow Join.' This prevents Revit from attempting to merge layers between the two dissimilar wall types. If the graphic is still unsatisfactory, use the Wall Joins tool (Modify tab) to select the junction and toggle to 'Butt' or 'Square Off.' Butt will terminate the partition against the concrete wall's face, while Square Off will ensure both walls maintain perpendicular end cuts. For the cleanest result in a gallery context, Butt is typically preferred because it clearly communicates that the partition is secondary to the primary concrete enclosure. You may also need to adjust the join order (which wall is dominant) by clicking the arrows in the Wall Joins tool interface to control which wall's layers take priority at the intersection.

Question 5: CRITICAL THINKING

A colleague argues that for a conceptual design competition, it is faster to model walls as generic extrusions (in-place model geometry) rather than using Revit's wall system families. Evaluate this argument by discussing at least three capabilities that are lost when walls are modeled as generic geometry, and propose a workflow that balances design freedom with BIM data integrity.

Show answer

Modeling walls as generic extrusions sacrifices several critical BIM capabilities. First, scheduling and quantification: system walls automatically appear in wall schedules with area, volume, and type data, enabling cost estimation and material takeoffs—generic geometry does not. Second, room bounding: Revit walls serve as room boundaries for area calculations and spatial analysis; generic extrusions do not bound rooms unless explicitly set. Third, hosted elements: doors and windows can only be hosted in wall system families, not in generic model geometry—you lose the ability to cut openings that update automatically. A balanced workflow would use Revit's massing tools to explore conceptual forms, then apply Wall by Face to convert mass surfaces into true wall elements, or use curtain walls with custom panels for non-standard geometries. This approach preserves the designer's formal freedom while maintaining the data structure that makes BIM valuable for documentation, coordination, and fabrication.

SUMMARY

Lesson Summary

Summary

Walls in Autodesk Revit are parametric building elements defined by three system families—Basic Wall, Curtain Wall, and Stacked Wall. Each wall instance is governed by a wall type that specifies its internal layer composition (finish, substrate, structure, thermal, and core boundary layers), vertical constraints that lock its base and top to project levels for automatic height adjustment, and join conditions (butt, miter, or square off) that control how layers merge or separate at corners, T-junctions, and intersections.

The Location Line setting determines which reference within the wall's thickness is used for placement and dimensioning—six options span from Wall Centerline to individual Core and Finish faces. For advanced design scenarios, Edit Profile reshapes the wall's elevation silhouette, vertically compound assemblies allow layer splits at specific heights, and Wall by Face applies wall types to freeform mass surfaces—bridging sculptural design intent with constructable BIM documentation.