Common
The standard symmetrical gable truss, flat ceiling and equal slopes. Fink, Howe, king-post and queen-post webbing depending on span.
Most residential roofs
Roof trusses
Roof trusses, engineered per job
Metal-plate-connected roof trusses in the profiles residential and light commercial framing actually calls for. Every truss is designed for your span, pitch, loads and bearing conditions — there is no standard truss.
Profiles
Truss types we fabricate
Profile describes the shape of the truss. Web configuration describes how the inside is triangulated, and it is chosen by the engineer to suit the span and loads.
Scissor
Sloped bottom chord that creates a vaulted ceiling inside the truss depth, without a structural ridge beam.
Vaulted great roomsAttic (room-in-attic)
Open rectangular space framed inside the truss for habitable or storage use. Floor loads must be specified up front.
Bonus rooms, storageHip and step-down hip
Hip sets that turn the roof down on all four sides, supplied as a coordinated bundle with the hip girder and jacks.
Hip roofsMono (single slope)
A single sloping top chord. Used for lean-tos, shed dormers, porches and agricultural or light commercial structures.
Sheds, porches, additionsGable end
Vertically studded end frame that matches the adjacent common truss profile and carries sheathing and siding at the gable.
Every gablePiggyback
A two-piece assembly for roofs too tall to transport in one piece. Base truss plus a cap set on site.
Steep or tall roofsGirder trusses
Multi-ply trusses that carry concentrated loads from other trusses. Ply count and fastening schedule come with the sealed drawings.
Point loads, hip setsValley sets
Framed valley sets that sit over a completed roof plane where two roofs intersect, instead of hand-cut valley framing.
Roof intersections
Materials
What goes into the truss
- LumberVisually graded and MSR SPF, Douglas Fir-Larch and Southern Pine, 2x4 through 2x12, grade stamps intact and verifiable on delivery.
- PlatesGalvanised 20-gauge and 18-gauge metal connector plates, sized and located by the truss design engineer rather than by rule of thumb.
- TreatedPressure-treated members with corrosion-resistant plates where the design calls for ground or moisture contact.
- BracingPermanent bracing requirements are shown on the drawings. Temporary erection bracing is the installer’s responsibility and is covered in the BCSI sheets we ship.
Specify this
Design inputs we need
Every one of these changes the truss. Give them to us up front and the first quote is the right quote.
| Input | Why it matters |
|---|---|
| Clear span | Sets chord size and web configuration |
| Roof pitch | Sets truss height and transport method |
| Heel height | Drives energy-code insulation depth at the eave |
| Overhang | Tail length, fascia and soffit detail |
| Top chord live load | Roofing, snow and construction loads |
| Bottom chord dead load | Ceiling, insulation, mechanical |
| Ground snow load | Governs design in most of the mountain west |
| Wind speed / exposure | Uplift connections at bearing |
| Spacing | 24" o.c. is typical; 16" changes the design |
| Bearing conditions | Wall, beam or girder support locations |
Also worth knowing
Two things that catch people out
Trusses cannot be field-modified
Cutting, drilling or notching a truss chord or web voids its engineering. If a duct or a beam needs to pass through, tell us before fabrication and the truss gets designed for it. A modification after delivery needs a new sealed repair detail, which costs time you do not have on site.
Attic trusses need floor loads
A room-in-attic truss carries a real floor. Tell us whether the space is storage or habitable, and what live load the code requires, before we design it. Retrofitting a heavier floor load means rebuilding the trusses.
