Thirteen truss examples from King Post to A-Frame, each with a schematic, its working span, and the trade it makes. Filter by family, tap a profile, and know exactly what you are ordering.
Filter by family, tap a profile, and read its span range, superpower, and watch-outs.
schematic — not to scale
W-shaped web pattern — four top-chord segments, fan webs to the bottom chord
Typical span
20–36 ft
Best for
The default truss of American house framing
✓ Short, well-braced web members use smaller lumber
✓ Factory-efficient: the most produced roof truss in North America
✗ Many web joints mean more plates to install
✗ No open space in the web zone for storage or rooms
What is a roof truss, in one sentence? A prefabricated triangle-based frame that carries a roof across a room using members in pure tension and compression — no bending anywhere. In construction terms, trusses replaced stick framing (rafters plus ceiling joists plus purlins plus struts) with a single engineered unit lifted into place by crane. Two framers set a 40-foot truss every few minutes; the same roof in stick framing would consume a day of cutting, and a structural ridge beam the truss never needed.
The magic is geometry, not lumber grade. A rectangle pushed at one corner folds into a parallelogram — that is bending and racking. A triangle has no such freedom: its shape is fixed by its three member lengths, so each member only stretches or squeezes. Trusses are therefore “triangulated beams”: the top chord works like the compression flange of a deep I-beam, the bottom chord like its tension flange, and the webbing like the web connecting them — at a fraction of the weight of solid timber.
Triangulation does the workPhoto: UnsplashThe chart below is the page in one table — the same thirteen profiles the explorer above presents one at a time. Span bands are the typical factory ranges for dimension-lumber trusses at 24-inch spacing; your plate supplier’s engineered numbers govern.
| Truss type | Typical span | Defining feature | Best for | Watch out |
|---|---|---|---|---|
| King Post | 12–24 ft | One central vertical post between the apex and the bottom chord | Sheds, garages, small gable roofs | Span caps out quickly as the single post does little work |
| Queen Post | 24–36 ft | Two vertical posts with a straining beam between them at the apex | Wider sheds, small barns, workshops | Middle third of the bottom chord is the weak link |
| Fink★ | 20–36 ft | W-shaped web pattern — four top-chord segments, fan webs to the bottom chord | The default truss of American house framing | Many web joints mean more plates to install |
| Howe | 24–40 ft | Verticals in tension, diagonals rising toward the apex (the traditional Howe arrangement) | Barns, agricultural buildings, heavier roof loads | Slightly more lumber than a Fink at equal span |
| Pratt | 24–48 ft | Diagonals slope down toward the center — verticals in compression, diagonals in tension | Long residential spans, light commercial roofs | Compression verticals need bracing attention |
| Warren | 30–80 ft+ | Alternating diagonals only — no verticals, members equal-length in a zigzag | Bridge trusses, long open floors, big industrial roofs | Long unbraced compression chord segments |
| Scissor★ | 16–40 ft | Both chords slope upward — the bottom chord forms the vaulted ceiling | Cathedral ceilings in great rooms and churches | Delivers horizontal thrust to the walls that a flat-bottom truss never does |
| Gambrel | 20–40 ft | Two slopes per side — steep lower pitch, shallow upper pitch — for a boxy loft volume | Barns, Dutch Colonial roofs, loft buildings | Two pitch breaks per side: more complex flashing and layout |
| Attic (Room-in-Truss)★ | 28–48 ft | Steepened top chords and raised webbing frame a walkable rectangular room inside the truss | Bonus rooms, studio apartments, home offices inside the roof | Needs 10/12+ pitch to yield real headroom |
| Mono | 12–32 ft | A right-triangle truss — one sloping top chord, one flat bottom chord | Shed roofs, lean-tos, add-ons, modern single-slope designs | Single-slope roofs limit ceiling options |
| Parallel Chord | 12–60 ft (as floor trusses) | Both chords parallel — a webbed steel-like beam in timber | Floor systems, flat roofs, long unsupported interior spans | Web triangles are off-limits to cutting — plumbers learn fast |
| Girder | Varies — sized for carried load | A heavy multi-ply truss that carries point loads from framing it supports | Supporting other trusses at hips, valleys and floor openings | Point-load connections are the design-critical detail |
| A-Frame | 16–32 ft | Rafters extended to act as walls — the roof plane reaches (near) the floor | Cabins, tiny homes, steep pitched A-frame houses | Steep angles waste floor area at the edges |
Each entry pairs the schematic from the explorer with the reasoning a builder actually uses: why the webbing looks that way, where the profile earns its keep, and what it costs you.
12–24 ft · Everyday Gable
One central vertical post between the apex and the bottom chord. Typical duty: Sheds, garages, small gable roofs.
24–36 ft · Everyday Gable
Two vertical posts with a straining beam between them at the apex. Typical duty: Wider sheds, small barns, workshops.
20–36 ft · Everyday Gable
W-shaped web pattern — four top-chord segments, fan webs to the bottom chord. Typical duty: The default truss of American house framing.
24–40 ft · Everyday Gable
Verticals in tension, diagonals rising toward the apex (the traditional Howe arrangement). Typical duty: Barns, agricultural buildings, heavier roof loads.
24–48 ft · Everyday Gable
Diagonals slope down toward the center — verticals in compression, diagonals in tension. Typical duty: Long residential spans, light commercial roofs.
30–80 ft+ · Bridge, Floor & Special
Alternating diagonals only — no verticals, members equal-length in a zigzag. Typical duty: Bridge trusses, long open floors, big industrial roofs.
16–40 ft · Ceiling & Open Space
Both chords slope upward — the bottom chord forms the vaulted ceiling. Typical duty: Cathedral ceilings in great rooms and churches.
20–40 ft · Ceiling & Open Space
Two slopes per side — steep lower pitch, shallow upper pitch — for a boxy loft volume. Typical duty: Barns, Dutch Colonial roofs, loft buildings.
28–48 ft · Room-in-Roof
Steepened top chords and raised webbing frame a walkable rectangular room inside the truss. Typical duty: Bonus rooms, studio apartments, home offices inside the roof.
12–32 ft · Everyday Gable
A right-triangle truss — one sloping top chord, one flat bottom chord. Typical duty: Shed roofs, lean-tos, add-ons, modern single-slope designs.
12–60 ft (as floor trusses) · Bridge, Floor & Special
Both chords parallel — a webbed steel-like beam in timber. Typical duty: Floor systems, flat roofs, long unsupported interior spans.
Varies — sized for carried load · Bridge, Floor & Special
A heavy multi-ply truss that carries point loads from framing it supports. Typical duty: Supporting other trusses at hips, valleys and floor openings.
16–32 ft · Ceiling & Open Space
Rafters extended to act as walls — the roof plane reaches (near) the floor. Typical duty: Cabins, tiny homes, steep pitched A-frame houses.
Every profile above shares the same skeleton. Learn these nine names and you can read any truss drawing — or argue intelligently with a plate supplier.
The two sloping outer members. Under gravity loads they work in compression — the roof's rafters, absorbed into the frame. Their top edge receives the sheathing.
The horizontal member joining the wall plates. Works in tension like a tie beam, doubles as the ceiling's framing, and — in attic profiles — carries the room's floor loads.
The inner diagonal and vertical members between the chords. They triangulate the frame and transfer shear; their pattern is what distinguishes a Fink from a Howe from a Pratt.
Toothed metal plates pressed over the joints in factories. Each connects chords and webs at panel points; plate size and nail embedding are the engineered part of the truss.
The joint where top and bottom chords meet at the wall plate. Heel height determines how much insulation fits at the eave — a detail energy codes keep raising.
The top-center joint where the top chords meet. In King Post profiles the king post hangs from it; ridge vents and caps terminate here.
The joints where webs meet chords. Purlins and point loads must land here — a load applied mid-member bends it, violating the tension-compression-only assumption.
The top-chord extension past the heel that forms the eave. Ordered in inches; feeds soffit, fascia, and gutter takeoffs.
An upsized truss — often two or three plies bolted together — that carries other trusses framing into it at hips, valleys, and stairwell openings. The literal 'beam truss'.
⚠️ Warning — never cut or notch webbing. “Truss webbing” looks like spare space to plumbers and attic-storage shoppers, but every web is a computed compression or tension member. Cutting one removes a triangle side and the whole truss reverts to a folding mechanism. Ducts route through the web zone of parallel chord trusses, never across a cut one — and any modification goes back to the plate supplier for a stamped repair detail.
The geometry catalog is identical on both sides of the fence — a Warren is a Warren whether it roofs a church or a warehouse. What changes is the brief the profile has to satisfy. The comparison below is the selection logic engineers apply before any drawing is made.
| Selection factor | Residential roof trusses | Commercial trusses |
|---|---|---|
| Dominant profiles | Fink, Howe, King Post; scissor and attic where space is sold | Warren, Pratt, parallel chord, heavy girder assemblies |
| Typical span band | 12–40 ft | 40–120 ft+ (often steel or heavy timber) |
| Governing loads | Snow, shingle weight, attic storage, wind uplift | Rooftop HVAC, suspended services, drone-level wind studies |
| Spacing & bays | 24 in o.c. standard; 16 in for heavy finishes | Wide bays on girder grids; purlin systems between trusses |
| Approval path | Supplier span tables + permit office | Stamped engineered drawings per project |
💡 Selection shortcut: start from the space, not the shape. Flat ceiling on walls → Fink or Howe. Cathedral ceiling → scissor (budget for wall thrust). Living space in the roof → attic truss at 10/12+. Barn volume under a low ridge → gambrel. Clear span past 40 ft or a floor → Warren, Pratt, or parallel chord. Every one of those profiles links to its dedicated calculator page in the explorer above, where the trade-offs get numbers.
A roof truss is a prefabricated structural frame — usually of dimension lumber joined by metal plates — that carries the roof load across a room in one piece. Its members (top chords, bottom chord, and webs) are arranged in triangles because a triangle is the only shape that cannot be pushed out of square: under load, its members work in pure tension and compression instead of bending. That is why a truss can span 40 feet from two wall plates while a single beam of the same lumber depth cannot. Most house trusses in North America are Fink profiles; barns lean on gambrels and Howes; cathedral ceilings demand scissors.
The two outer sloping members are the top chords; the horizontal member joining the wall plates is the bottom chord; the inner bracing members are the webs (sometimes called webbing or web members). Joints are held by toothed metal gusset plates, the triangle corners have names — heel where top chord meets bottom chord, apex or peak at the top center — and intermediate member intersections are panel points. A girder truss is an upsized, often multi-ply truss that supports other trusses. The full glossary with each part's job is in the anatomy section above.
A rafter is a single sloping beam that must resist bending along its length, so it needs a ridge board or beam and ceiling joists to keep the roof from spreading. A truss replaces that assembly with a triangulated frame: top chords do the rafter's job, the bottom chord does the ceiling joist's job, and webs keep everything triangular. The practical result is that trusses span wider, use smaller lumber, install in minutes by crane, and arrive with the ceiling structure built in — but leave no open attic unless you order an attic or room-in-truss profile.
Match the profile to span and purpose. Up to 24 ft, a King Post or Fink is the economical answer. From 24 to 36 ft, Fink and Howe dominate residential work. Past 36 ft, look at Pratt, or a modified Fink with extra webbing. Want a cathedral ceiling at any span — that is a scissor. Want living space inside the roof — an attic truss with a 10/12 or steeper pitch. Barn or Dutch Colonial volume — a gambrel. Flat floors and long clear spans between supports — parallel chord trusses. The span-versus-profile chart above gives the typical band for every type.
A truss behaves like a deep beam built out of triangles: the top chord compresses, the bottom chord tensions, and the webbing transfers shear between them — exactly the stress pattern inside a solid beam, but with most of the dead weight removed. That is why long-span roof and bridge structures choose trusses: they deliver beam action with a fraction of the material. 'Beam truss' colloquially describes this behavior, and a girder truss is the literal case — an upsized truss doing a beam's job by carrying point loads from other trusses framing into it.
Truss webbing is simply the collective term for the web members — the diagonal and vertical members between the top and bottom chords. Their job is to keep the chords working as one deep triangulated beam by transferring forces at the panel points. Different webbing patterns define different truss types: the W-shape makes a Fink, rising diagonals make a Howe, falling diagonals a Pratt, and zigzag-only webbing a Warren. Webbing is also the reason trusses resist spreading: no triangle in the frame can deform without one of its members changing length.
Commercial roofs lean on long-span profiles: Warren and Pratt trusses for clear spans past 40 feet, parallel chord trusses as floor joists in multi-storey buildings, and girder trusses wherever hip or valley lines concentrate loads. Heavy timber and steel versions of the same triangles appear in warehouses, arenas, and churches. The selection logic differs from residential mainly in load magnitude and fire or serviceability requirements — the geometry families above stay the same, but members are sized by engineered load cases rather than stock span tables.
Scissor truss calculator for cathedral ceilings: check interior clearance vs wall thrust, see truss depth effects, and compare spans before you build.
Attic truss calculator with a room-in-truss size chart: usable room width and height by span, chord load differences, and bonus room planning data.
Gambrel truss calculator: the two-slope angle method, section lengths, barn roof height by span, and a full 12 ft gambrel roof example.
Roof truss design calculator and build-your-own workflow: pick a type, set span and pitch, run member forces, and hand clean numbers to your supplier.
Shed roof truss design calculator for mono pitch and lean-to roofs: one-slope geometry, wall connection checks, and a full 12 ft shed worked example.
Floor truss calculator for open-web and flat truss design: depth-vs-span tables, L/360 deflection checks, plumbing routing wins, and a preloaded model.
Steel truss calculator for metal truss design: set E = 29,000 ksi, compare steel vs wood member forces on the same frame, and use the section-area table.
Bridge truss calculator with one-click Pratt, Howe and Warren models: same load, three force tables, and classroom-ready comparison steps.
Free 2D truss analysis calculator with steps: model any truss, solve reactions, displacements and member forces, and audit the full stiffness report.
Truss load calculator that converts psf roof loads into joint point loads: tributary width, dead, live and snow values, worked examples, and deep-linked models.
Roof truss span calculator: turn span and pitch into truss length, ridge height, and angle — with 4/12 and 6/12 quick examples and plumb cut angles.
Truss cost calculator: price ranges by span and pitch, weight and delivery estimates, labor factors, and the spec list to send manufacturers.
Truss spacing calculator: 16 vs 24 inch on-center logic, the truss count formula, load-span-spacing limits, and rafter spacing comparisons.
Free metric roof truss calculator for UK, Australia, NZ & Canada: span, pitch in degrees, truss length and height in mm, with C24/MGP10 timber notes.
Free rafter length calculator: turn span, pitch and overhang into rafter length, plumb cut angle and birdsmouth seat cut, with 4/12-12/12 tables.
King post truss calculator: preload a 16 ft model, hand-check member forces, size the post, and see span-to-rise rules and curved-bottom variants.
Learn to calculate truss forces by hand: the method of joints rule set, two fully worked examples, a method of sections shortcut, a printable truss calculations worksheet, and stress-ratio strength checks — each verifiable in the free calculator.
A quantified reference for common truss sizes: a master chart from 12 ft to 40 ft spans with chord sizes (2x4 vs 2x6), web configurations, spacing and applications, plus per-span detail blocks and a truss count calculator.
The only factory-side guide on this site: how prefabricated wood roof trusses are manufactured — design software, jigs, hydraulic plate presses, engineered lumber — plus the custom-truss ordering workflow, typical lead times, and the questions to ask roof truss manufacturers before you order.
An application guide to pole barn trusses: why post-frame buildings use wide 8-foot truss spacing, steel vs wood comparisons, ready-to-model 30 ft and 40 ft barn truss schemes with deep links into the calculator, and the full purlin-and-truss layout sequence from pole to ridge.
A methodology-first walkthrough of PLTW POE Activity 2.1.7 calculating truss forces: reaction steps, joint-by-joint equilibrium on a 30° Warren truss with a 1 lb center load, section-cut verification, and a five-test answer-checking routine — every number reproducible in the free calculator.
A scenario-based comparison of truss calculation software: browser calculators for quick force checks, Excel templates for repeated geometry, MATLAB and Python scripts for batch studies, MDSolids for coursework, and SkyCiv, Medeek, MiTek or ETABS for engineered and manufactured work.
A structural tour of timber frame trusses: how heavy timber differs from light prefab, the king post, queen post, hammerbeam and cruck forms with their span envelopes, glulam grades including 24F-1.8E, and the load path through mortise-and-tenon pegged joints — with a free span checker.
Ready to run numbers on the profile you picked? The free truss calculator models all of these shapes and returns every member force.