Alphabetical by name of thing. Please suggest improvements and additions. Many things have changed, many have stayed the same. Layer theory hasn't changed much. Current as of Archicad 20, which prompted some layer changes.
Big table below the fold.
| Item | Layer | Note |
|---|---|---|
| Area Calculation Fill | Z Measurement | |
| Baseboard | F Trim Int Lo | |
| Bathtub | P Fixture | |
| Beam, Moment Frame | S Frame Beam | For Wall Bracing plan |
| Beam, Structural | S Beam | To show in 3D |
| Beam, Structural | S Framing | To show in Structure Plan only |
| Bench | F Counter | |
| Bookshelves | F Shelves | |
| Bracket | F Trim Int/Ext Hi | |
| Builtin Labels ("Bench") | +A Arch Note Reg Scale | |
| Cabinet, Base | F Cabinet Base | |
| Cabinet, Upper | F Cabinet Upper | |
| Cabinet parts, 3D | F Cabs3 | To show in 3D only |
| Car; Plan | F Furniture | |
| Ceiling, attic | A Ceiling3 | Slab within roofs |
| Ceiling, lowered | A Ceiling3 | Slab below story above's S Deck slab |
| Ceiling lines | A Ceiling2 | |
| Chair Rail | F Trim Int/Ext Mid | |
| Chimney Parts | A Fireplace/Chimney2 | To show in Plan |
| Chimney Parts | A Chimney/Fireplace3 | To show in 3D only |
| Clip Line (Ceiling) | A Ceiling2 | |
| Closet Shelf | F Cabinet Upper | |
| Coffer Beams | A Soffit2 | Use a dotted line for the beam or slab. |
| Column, Decorative | F Trim Int/Ext Mid | To show in 3D only |
| Column, Decorative | A Wall Int/Ext | To show in Plan |
| Column, Moment Frame | S Frame Column | For Wall Bracing plan |
| Column, Structural | S Column | |
| Concrete Slab | S Slab | 3D Only |
| Cooktop | A Appliance | |
| Countertop | F Counter | |
| Crown Moulding | F Trim Int/Ext Hi | 3D Only |
| Crown Moulding (RCP) | F Trim Crown | To show in RCP |
| Cutline, Stair | A Stair2 | Use object's cutline feature |
| Deck Railing | A Deck Railing | |
| Deck Structure | S Deck | |
| Deck Surface | A Deck2 | To show in Plan |
| Deck Surface | A Deck3 | To show in 3D only |
| Decorative items, non-furniture | F Decor | BIMx and render only |
| Detail Marker | Note layer of drawing type | |
| Downspout | F Gutter | |
| Drawing Area (Object) | +Z Drawing Area | |
| Drawing in Layout | +Z Layout | |
| Plan Title | Note layer of drawing type | Only plans have title objects in the window |
| Driveway (Mesh) | L Drive3 | |
| Elec Fixtures | Complicated. | |
| Elec Fixture, Wall & Floor, Symbol only | E Symbol | To show in Elec Plan |
| Elec Fixtures, Wall & Floor, 3D | E Wall Fixture | To show in Elec Plan, Int Elev |
| Elec Fixture Symbols, Ceiling, Symbol Only | E Ceiling Symbol | To show in Elec Plan, RCP |
| Elec Fixtures, Ceiling, 3D | E Ceiling Fixture | To show in Elec Plan, RCP, Int Elev |
| Elec Fixtures, Exterior, 3D | E Ext Fixture | To show in Elec Plan, Elevations, BIMx |
| Elec Fixtures, Ext, Clg, 3D | E Ext Ceiling Fixture | To show in EP, RCP, 1/4" Elevs, BIMx |
| Elevator | A Wall Int | Bugs me, but not enough to have a single-element layer |
| Energy Calculation Fill | Z Measurement | |
| Fireplace | A Fireplace/Chimney2 | |
| Floor joist deck | S Deck | |
| Floor Pattern | F Floor Fin2 | Fills |
| Flooring, Finish | F Floor Fin3 | 3D Only |
| Chimney Flue | A Fireplace/Chimney2 | A Fireplace/Chimney3 to hide in plan |
| Footing | S Footing | Use a dotted line for the slab. |
| Foundation Perimeter on Site Plan | +C Footprint | |
| Foundation Walls & Piers | S Wall2 | Plan & 3D |
| Foundation Walls & Piers | S Wall3 | 3D Only |
| Furniture | F Furniture | |
| Gutter | F Gutter | |
| Hearth, flush | F Floor Fin2 | |
| Hearth, raised | F Counter | |
| HVAC Register, Floor | M Fixture | |
| HVAC Register, Ceiling | M Ceiling Fixture | |
| Hotspot (Drawing Aid) | ! Non-Print, ! Site Non-Print | Not needed, use sparingly, reconsider. |
| Hotspot (Plan Alignment) | Archicad Layer | |
| House on Site Plan | +L House Line | 3D Top View drawing is better |
| Interior Elevation Marker | +Z SE Hide | To hide in plan |
| Interior Elevation Marker | +Z SE Show | To show in plan |
| Joists, 2D Fill | S Framing | |
| Joists, Modeled | S Framing | Very rare, optional |
| Label | Note layer of drawing type | |
| Mantel | F Trim Int/Ext Mid | |
| Mask Fills, Sect/Elev | +A Misc Line | |
| Mech Equipment | M Equip | Plan, Mech Plan, 3D |
| Note Text | Note layer of drawing type | |
| Object Creation Resources | Z Object Lab | Slabifying slabs, e.g. |
| Oven, wall | F Cabs3 | The oven itself. The cabinet goes on F Shelves. |
| Oven, wall | A Appliance | To show in plan |
| Outlet, Electrical, symbol only | E Symbol2 | Electrical plan |
| Outlet, Electrical, 3D | E Wall Fixture3 | Electrical plan, Int Elev |
| Panels | F Trim Int/Ext Mid | Thin wall with panel windows or objects |
| Panels, trim, in slabs/roofs | F Trim Int/Ext Hi | 3D Only |
| Panels, trim, in slabs/roofs | F Trim Crown | To show in RCP |
| Pantry Shelves | F Shelves | |
| Pantry cabinet (built with walls) | F Shelves | |
| Patches | Layer of patched elements | Usually a Wall layer. In Sect/Elev, use +A Misc Line |
| Pergola | F Trellis | |
| Picture (Scanned) | Z Image Scan | |
| Pool | A Deck2 | |
| Refrigertor | A Appliance | |
| Roof Overhang | A Soffit2 | Polylines |
| Roof | A Roof2 | Plan and 3D |
| Roof | A Roof3 | 3D Only |
| Room Name Object | +Z Zones | Use zones instead |
| Sconce, 3D | E Wall Fixture | |
| Sconce, symbol | E Symbol | |
| Section or Elevation Marker | +Z SE Hide | To hide in plan output |
| Section or Elevation Marker | +Z SE Show | To show in plan output |
| Shower Head | P Fixture | |
| Shower Pan | P Fixture | |
| Sink | P Fixture | |
| Site (Mesh) | C Site3 | |
| Site (Mesh), original | C Site3 Existing | Backup of site data |
| Site Boundary | C Site2 | |
| Site Topo Contour (Existing) | C Topo Existing | |
| Site Topo Contour (Modified) | C Topo New | |
| Site Topo Labels | +C Site Note | |
| Soffit, Exterior | A Soffit3 | |
| Soffit panels | F Trim Crown | To show in RCP, overwise F Trim Int Hi |
| Solid Element Operators | X SEO General | |
| Stair Arrow | +A Arch Note Reg Scale | |
| Stair Newel | A Stair Railing | |
| Stair Railing | A Stair Railing | To hide in Structure Plan |
| Stair Stringer (Wall, Object) | A Stair3 | |
| Stair Tread (Slab, Roof, Object) | A Stair2 | If it looks good, otherwise A Stair3 |
| Stair Tread 2D | A Stair2 | If real treads don't look good |
| Switch, Electrical, symbol only | E Symbol2 | Electrical plan |
| Switch, Electrical, 3D | E Wall Fixture3 | Electrical plan, Int Elev |
| Switch Path (Electrical) | +E Elec Note | |
| Terrace | A Deck2 | |
| Toilet | P Fixture | |
| Tree, Model | L Tree3 | |
| Tree, Symbol | L Tree2 | |
| Trellis | F Trellis | |
| Vanity Top | F Counter | |
| Wainscot | F Trim Int Lo | |
| Wall Poche Mask | +A Wall Mask | |
| Washer/Dryer | A Appliance | |
| Zone | +Z Zones |