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Reference library

Building Components

Reference entries for the discrete elements a building is assembled from — named by where they sit and what they do, rather than by what they are bought as. Each explains what the element is, what it depends on, the material families it is commonly formed from, the systems it belongs to, and the junctions where it meets other elements.

192 components across 15 categories, connected to 96 junction concepts and 25 building contexts.

How this library differs from the other two

Materials are what you procure — a substance or a product format that can be specified and delivered. Plasterboard, structural softwood and facing brick are materials, and each has an entry in the Materials Library.

Components are what you position — an element identified by where it sits in an assembly and what job it does there. A wall stud, an outer leaf and a rafter are positions, and the same position can be realised in several different materials. That is what these pages describe.

Systems are what components add up to — a coordinated assembly whose parts interact, explained in the Building Systems Encyclopedia.

Where an element already has a Materials Library entry — a lintel, a wall tie, a roof truss, a damp-proof course — this library does not repeat it. It links to it instead.

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Structure & Ground

Elements that carry load or prepare the ground to receive it — from the surface a foundation bears on, through the joints and reinforcement positions that govern cast concrete, to the members and connections that span between supports.

18 entriesSubstructure & Ground →The prepared surfaces, layers and buried members between undisturbed ground and the first structure above it.38 entriesFrame Members →The columns, beams, joists, rafters, plates and bracing that make up a load-carrying frame, identified by the position each occupies.5 entriesConcrete & Reinforcement →The positions that govern how concrete is placed, joined and reinforced — the joints between pours, the zones around reinforcement, and the faces that form the finished surface.

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Envelope Elements

Elements of the outer shell: the leaves that form a wall, the carcass and edges of a roof, the framing around openings, the supports behind a facade, the layers that control heat and water, and the pieces that terminate them.

22 entriesWall Leaves & Backing →The distinct vertical layers that make up a wall — outer and inner leaves, the cavity between them, and the backing that supports what is fixed to the face.13 entriesRoof Carcass & Edges →The battens, boards and edge elements that finish a roof structure and prepare it to receive a covering.13 entriesOpenings & Frames →The frames, heads, jambs, sills, thresholds and closers that form and finish an opening through a wall.10 entriesFacade Support →The brackets, rails, subframes and framing members that hold a facade off a backing structure, and the panels they carry.7 entriesLayers & Barriers →Continuous positioned layers within a build-up — insulation, separation, protection, drainage and root barriers — named by the job they do rather than the product used.8 entriesTerminations →The elements where a plane stops, turns up, sheds water or is deliberately interrupted — parapets, upstands, flashings, drips, weeps and movement joints.

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Interior Elements

Elements within the occupied volume: the layers built up on a structural floor, the framing and voids above a ceiling, the positions that make up a stair, and the shafts, chases and openings left in the fabric for services.

8 entriesFloor Build-Up →The deck, toppings, floating layers, isolation strips and voids that sit between a floor structure and its finish.10 entriesCeilings & Voids →The joists, hangers, independent frames, voids and access provisions that form the plane above a room and the space behind it.10 entriesStairs & Level Change →The positions that make up a stair and the elements that carry people safely between levels — treads, risers, the members beneath them, and the guarding at the edge.7 entriesService Zones & Penetrations →The voids, shafts, chases and openings left in the fabric so services can pass through it and be reached again afterwards.

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Water & External Elements

Elements outside the enclosure: the build-up beneath paving and decks, and the elements that collect, carry and discharge water.

10 entriesPaving & Decks →The laying course, wearing course, edge restraint, deck framing, guarding posts and the enclosing and surfacing elements that make up the ground outside the building.13 entriesDrainage Elements →The gutters, outlets, downpipes, channels, chambers and traps that collect water, carry it and let it be inspected.

Junctions

Interfaces between components

Junction concepts where the condition between two elements governs how the construction behaves. These are a data layer rather than a set of pages: each surfaces on the pages of the components it connects, because a junction concept without those two elements around it would be a page with nothing substantive to say. They name what a junction has to do and the subjects it raises — they are never details, arrangements or approved ways of building.

Envelope junctions
  • Cavity Barrier Across a Cavity
  • Facade Bracket Through Insulation
  • Outer Leaf to Inner Leaf Restraint
  • Sheathing to Frame
  • Slab Edge to External Wall
  • Wall Head to Roof Insulation Continuity
  • Beam to Masonry Infill Panel
  • Brick Support Angle to Outer Leaf
  • Cavity Barrier to Service Penetration
  • Column to Masonry Infill Panel
  • Insulation Layer to Parapet
  • Mullion to Transom
  • Rainscreen Panel to Support Rail
  • Slab Edge to Spandrel Panel
  • Support Bracket to Support Rail
Finish transitions
  • Movement Joint Through a Surface
  • Reveal to Frame
  • Ceiling Grid Tee to Ceiling Perimeter Trim
Floor & wall junctions
  • Floating Layer to Perimeter
  • Partition Head to Ceiling Void
  • Sleeper Wall to Subfloor Ventilation
  • Topping to Structural Deck
  • Access Panel to Riser Shaft
  • Deflection Head to Structural Deck
  • Floating Floor Layer to Service Penetration
  • Floor Joist to Head Binder
  • Raised Floor Panel to Raised Floor Pedestal
  • Raised Floor Pedestal to Structural Deck
  • Slab Edge to Sole Plate
  • Sleeper Wall to Wall Plate
Moisture-control junctions
  • Cavity Tray to Weep Discharge
  • Membrane to Roof Outlet
  • Protection Over Waterproofing
  • Upstand to Flashing Termination
  • Wall Base Damp-Proofing Junction
  • Wet Area Floor to Wall Tanking
  • Construction Joint to Pool Tank Wall
  • Downpipe to Gully
  • Filter & Separation Layer to Subgrade
  • Masonry Pier to Pier Cap
  • Roof Walkway to Waterproofing Layer
Opening interfaces
  • Cavity Closer to Frame
  • Frame to Opening Head
  • Frame to Jamb
  • Sill to Frame
  • Threshold to External Ground
  • Door Frame to Door Leaf
  • Door Frame to Door Threshold
  • Door Threshold to Threshold Upstand
  • Frame Packer to Opening Jamb
  • Opening Jamb to Window Sill
  • Window Frame to Window Sash
Roof junctions
  • Counter-Batten to Tile Batten
  • Eaves to Gutter Discharge
  • Jack Rafter to Hip
  • Jack Rafter to Valley
  • Parapet Base to Roof Upstand
  • Rafter to Ridge
  • Tilting Fillet at Upstand Base
  • Verge Covering Termination
  • Back Gutter to Chimney Stack
  • Chimney Stack to Flashing
  • Firring Piece to Structural Deck
  • Gutter to Hopper Head
  • Overflow Outlet to Parapet
  • Plant Support Plinth to Upstand
Structural connections
  • Beam End to Column
  • Column Base to Foundation
  • Ground Beam Bearing on a Cap
  • Joist End to Masonry Bearing
  • Purlin to Strut Support
  • Rafter Foot to Wall Plate
  • Trimmer to Trimming Joist
  • Arch Springer to Masonry Pier
  • Balustrade Post to Stair Landing
  • Beam Bearing on a Corbel
  • Bracing Member to Gusset Connection
  • Cantilever Member to Thermal Break Pad
  • Ceiling Hanger to Structural Deck
  • Ceiling Joist to Rafter
  • Collar Tie to Rafter
  • Column to Portal Frame Haunch
  • Column Bearing on a Transfer Beam
  • Construction Joint to Starter Bar
  • Ground Anchor to Retaining Stem
  • Inner Leaf to Wall Plate
  • Kicker to Retaining Stem
  • King Post to Truss Chord
  • Pile Cap to Pile Shaft
  • Purlin to Rafter
  • Shear Wall to Structural Deck
  • Stair Carriage to Stair Tread
  • Stair Landing to Stair Stringer
  • Stair Landing to Trimmer
  • Stair Stringer to Stair Tread
  • Truss Chord to Truss Web Member

Contexts

Where components are applied

Functional building contexts — where in a building, and for what purpose. Also a data layer: an application groups components and systems rather than adding knowledge of its own, and a page per context would restate what those entries already say. A component listed against a context is commonly encountered there; that is an association, never a recommendation.

Envelope
  • Building Envelope — External Wall, Facade, Flat Roof, Opening, Pitched Roof
External works
  • External Works — Boundary Structure, Deck & Terrace, Hardstanding, Planted Construction, Site Drainage, Sports & Play Surface
Interior
  • Building Interior — Ceiling, Internal Partition, Separating Construction, Wet Area
Structure
  • Superstructure — Intermediate Floor, Stair & Ramp, Structural Fire Protection
Substructure
  • Substructure — Basement, Ground Floor