Takeoff & Estimating — Wood, Framing & Millwork

Truss

A triangulated framework of members that spans an opening, usually a roof.

Quick Answer

A truss is a framework of straight members arranged in triangles so that the pieces carry mainly tension and compression. Roof trusses span between bearing walls and support the roof deck, and they are made of wood or steel. Estimators count them by the piece, each with its span, pitch and type.

The Full Picture

A truss replaces a deep solid beam with a lightweight frame. Top and bottom chords are tied together with web members that form triangles, so loads travel through the members as tension or compression. In light-frame work the standard product is the metal plate connected wood truss, which the Truss Plate Institute describes as an engineered structural component. Steel trusses, built from angles, tubes or open-web sections, are used for longer spans, industrial buildings and heavier roof loads. The word also covers floor trusses, scissor trusses, girder trusses and gable-end trusses.

A truss sits on the top plate of the bearing walls and carries the roof deck and the loads on it. Trusses are normally spaced on a regular layout, often 24 in on center for wood roofs, but the layout comes from the roof framing plan, which also shows girder trusses, jacks and special conditions. Each truss is custom engineered by the supplier from the roof geometry and loads, so a supplier's shop drawings usually confirm the final mark list and bracing.

The takeoff unit is each (EA), by truss type or mark. For a roof framing plan, the estimator counts regular trusses by marked type, then gable-end trusses, girders, hip sets and any special pieces. Spacing sets the count: divide the length of roof by the spacing and add one. Lumber in a wood truss is not taken off, since the supplier prices the assembled truss. Steel trusses may be counted by piece or by weight in tons, according to how the structural steel is priced, and they bring their own erection and bracing.

Common mistakes include missing the girders or the hip and valley sets, pricing the truss without the bracing, bearing hardware and temporary stabilizing material, and forgetting the crane or lift needed for long spans. Delivery is a separate cost on large trusses, and the drawings for a truss package should be matched to the roof plan before the number is closed. Truss cost is also sensitive to span and pitch, so a changed roof plan changes the count and the type, not just the price.

Real Examples

→Worked takeoff: truss count: A building is 46 ft long, with trusses at 24 in on center. 46 ft x 12 = 552 in, and 552 / 24 = 23 spaces, so 23 + 1 = 24 trusses, with the two end trusses included in that count. If the roof plan marks 2 of those as gable-end trusses, the estimate carries 22 common trusses and 2 gable-end trusses.

→Girder and hip sets: A roof plan shows a hip end. The estimator counts the common trusses, the girder truss that supports the hip jacks, and the hip set pieces from the plan marks. The supplier's quotation confirms the list, and any difference is resolved before the price is final.

→Steel truss by weight: A warehouse roof uses steel trusses. The structural sheets give the member sizes, so the estimator may carry the trusses in tons with the rest of the structural steel or as an each count from a fabricator quote, whichever the bid package calls for.

Common Misconceptions

People assume: A truss is just a rafter and a joist put together.

Actually: A truss is an engineered assembly of chords and webs whose members work together, and it cannot be cut or altered on site without the engineer's approval.

People assume: Truss price covers everything to the roof deck.

Actually: Bracing, bearing hardware, lifting equipment, delivery and sheathing are often separate lines. Check what the quote includes.

People assume: Wood trusses are priced by lumber quantity.

Actually: The supplier prices the finished truss, so the estimator counts pieces by type, not board feet.

Does MeltPlan Solve This?

Partially — adjacent

Truss marks, spans and spacing are read from roof framing plans, and MeltPlan's takeoff service applies to counting from those plans: AI pulls quantities from plans and US-based experienced estimators review and adjust them. Engineering, supplier quotes and the final truss package stay with the supplier and your estimator.

Get truss counts taken off your roof framing plans →

Frequently Asked Questions

How are trusses counted in a takeoff?

Each truss is counted by piece and by type or mark from the roof framing plan. Common, gable-end, girder, hip and special trusses are listed separately because their prices differ.

What are trusses made of?

Light-frame roofs usually use metal plate connected wood trusses. Longer spans and heavier loads use steel trusses built from angles, tubes or open-web sections.

What is the difference between a truss and a rafter?

A rafter is a single sloped member that works with a ridge and ceiling joists. A truss is a complete engineered frame that spans between supports without interior bearing.

Who designs a roof truss?

The truss supplier or fabricator usually engineers each truss from the roof plan and loads, and the building's engineer of record reviews it. The estimator uses the framing plan and the supplier's quote to confirm the count.