Prefabricated Roof Truss RFQ Checklist: How to Specify Span, Loads, Connections, Transport and Installation

A useful prefabricated roof truss RFQ should state the building geometry, actual support span, roof form, roof build-up, attached equipment, connection interfaces, delivery constraints and installation responsibilities. It should also identify who will confirm the final structural design and design loads. A floor area and a short request for a price are not enough for suppliers to prepare directly comparable quotations.

The buyer is not expected to calculate the structure. The buyer's role is to assemble the project inputs, drawings, site conditions and scope boundaries that the roof truss supplier needs. The supplier should not be left to infer support locations, loading or site responsibilities from a general floor plan.

Why is roof area alone insufficient for comparing quotations?

Two roofs with the same area can require different truss quantities, member sizes, connection details and erection methods. Price per square foot or square metre is therefore useful only for an early indication, not for a final like-for-like comparison.

• The clear span and distance between structural supports may differ.
• Roof pitch, eaves level, ridge height and roof geometry may differ.
• Roof covering, insulation, ceilings and mounted services may impose different requirements.
• Trusses may be delivered fully assembled, in sections or as loose components.
• One price may include design, connections, transport and erection while another covers fabrication only.

What information should be prepared before requesting a roof truss quotation?

A comparable RFQ should cover the building, structural interfaces, roof assembly, logistics, installation and handover documents. The following table is a practical minimum-information checklist.

How should span and roof geometry be described?

A statement such as “12-metre building width” does not necessarily mean a 12-metre truss span. External wall dimensions, gridline distances, centre-to-centre support dimensions, bearing-face distances and clear spans may all be different. The RFQ should identify exactly which dimension is being used.

Provide the building plan, roof plan, column or loadbearing-wall grid, cross-sections, roof pitch, eaves level, ridge level and overhangs. Show changes in roof level, hips, valleys, skylights, access openings and equipment penetrations. Where trusses bear on concrete beams or steel columns, include bearing dimensions, levels and information on embedded plates or anchors.

Who should confirm the roof truss loads?

The procurement team can identify the materials and equipment that the roof must carry, but it should not invent structural load values. The final loading conditions should be confirmed by the qualified professional responsible for the project's structural design and approval, taking account of the building use, site, roof system and applicable project requirements.

Relevant inputs may include the truss self-weight, roofing, waterproofing, insulation, ceilings, purlins, lighting, suspended services, solar panels, maintenance access and the applicable construction, maintenance and wind conditions. These inputs must be coordinated instead of being hidden inside a general phrase such as “standard roof load”.

Future solar panels, tanks or mechanical equipment should be declared at the RFQ stage. If they were not considered in the original design, the completed truss should not be assumed to have spare capacity. Obtain a professional assessment before adding load or new fixing points.

How should light gauge and conventional steel trusses be specified?

Neither system should be selected solely by product name or unit material price. Span, loading, roof form, exposure, transport and construction conditions determine which engineered solution is appropriate.

If the buyer has not selected a system, the RFQ can invite suppliers to propose a suitable solution. Each proposal should state its design basis, member specification, connection method, delivery arrangement and erection scope.

Why must connections and interfaces be listed separately?

Designing the truss members does not automatically settle responsibility for every roof interface. The RFQ should allocate design, supply and installation responsibility for:

• Truss bearings and connections to concrete beams, steel columns or loadbearing walls.
• Splices in segmented trusses and permanent bracing between trusses.
• Purlins, roof covering, overhangs and edge members.
• Anchor bolts, embedded items, bearing plates and site connection materials.
• Ceiling, M&E services and accessory support or suspension points.

If a quotation merely says “connectors included”, ask for the type, quantity, material, protection and installation responsibility. Site cutting, drilling, welding or moving a connection is not routine adjustment; structural changes should receive written approval from the responsible designer before work proceeds.

What transport information belongs in the RFQ?

Whether a prefabricated truss can travel as a complete assembly depends on its length, height, weight and the access route. A truss that is easy to fabricate may still be impossible to deliver through a narrow gate or restricted road.

Provide the site address and entrance, road width, turning space, gate dimensions, overhead restrictions, unloading zone, ground conditions, storage area and permitted delivery hours. Ask the supplier to state the largest delivery unit, whether components arrive complete or segmented, how site splices will be made, who unloads, how components are restrained in transit, and who repairs transport damage or coating scratches.

How can the erection scope be made unambiguous?

The phrase “supply and install roof trusses” is still too broad. Every quotation should identify the labour, plant, access equipment, temporary works, permanent components and inspections included.

Temporary bracing deserves explicit attention. Before all permanent connections and bracing are complete, individual trusses may not yet form the final stable system. The erection method and temporary stability measures should therefore be agreed before installation begins.

How should competing roof truss quotations be evaluated?

Start by normalising the scope, not by ranking the total prices. Place every supplier's design basis, materials, connections, logistics, erection and exclusions into one comparison schedule.

Which omissions commonly create additional cost?

Using building width as truss span

An incorrect support dimension can affect design, drawings, pricing and fabrication, leading to rework or a revised proposal.

Omitting the roof covering and future equipment

Roof tiles, metal sheets, ceilings, solar panels and services have different loading and connection requirements.

Ignoring access and storage

Restricted vehicle access, an unsuitable unloading zone or poor storage conditions can add segmentation, handling, waiting time and damage risk.

Assuming crane and temporary bracing are included

Some installation prices cover labour only and exclude cranes, scaffolding, elevated platforms or temporary stability measures.

Changing the roof after drawing approval

Changes to pitch, overhang, openings or mounted equipment after fabrication starts normally affect materials, programme and cost.

A practical roof truss RFQ format

Arrange the RFQ in the following order and require each supplier to respond item by item:

1. Project name, location and building use.
2. Building plans, sections and roof drawings.
3. Truss spans, spacing, pitch, levels and overhangs.
4. Supporting structure, interfaces and site-measurement responsibility.
5. Roof covering, insulation, ceiling, drainage and attached equipment.
6. Design criteria confirmed by the project design team.
7. Specified truss system, or an invitation for an engineered proposal.
8. Material, corrosion protection, connection and document requirements.
9. Design, fabrication, transport, unloading, lifting and erection responsibilities.
10. Road access, delivery hours, storage and construction restrictions.
11. Quantities, delivery batches, target dates and inspection arrangements.
12. Warranty, exclusions, variation procedure and additional-charge basis.

Ask suppliers to separate design, materials, connectors, transport, lifting and erection prices where practical, and to list every exclusion. This makes scope differences visible before award rather than after fabrication.

What should be checked before placing the order?

• The quotation uses the same drawing revision as the final project information.
• Span, pitch, supports, roof build-up and attached equipment are confirmed.
• Engineering, drawing approval and site-measurement responsibilities are allocated.
• Member specifications, protective system and connection method are recorded.
• Transport segmentation, site assembly, lifting and bracing arrangements are described.
• Required handover documents, warranty and exclusions form part of the purchase scope.
• Variation, delay, extra delivery and waiting-time charges are addressed.

Frequently Asked Questions

1. Can roof trusses be quoted by building area alone?

Area may support a very early budget estimate, but a final quotation also needs span, pitch, supports, loading, materials and scope.

2. Is the truss span the same as the external building width?

Not necessarily. Span relates to the actual supports and should be confirmed from the structural layout, grids and bearing positions.

3. Who determines the design loads?

The qualified professional responsible for the project's structural design and approval should determine the loads using the building use, site, roof system and attached equipment.

4. Are light gauge steel trusses always cheaper?

No. Total cost also depends on span, loading, geometry, connections, corrosion protection, transport and erection.

5. How should the truss system be selected?

Selection should consider project-specific structural design, use, span, loads, environment, construction access and maintenance, not material price alone.

6. Can solar panels be added after the roof is completed?

Do not assume so. Solar panels add weight, fixing points and wind effects; the responsible professional should assess the existing structure first.

7. Are drawings necessary for an RFQ?

For a formal quotation, provide at least the building plan, roof plan and relevant sections. Written dimensions alone can be misunderstood.

8. Does “supply and install” include a crane?

Not automatically. Confirm unloading, cranes, mobile platforms, scaffolding, operators and lifting supervision separately.

9. Why should transport be priced separately?

Member size, route constraints, delivery frequency and unloading method affect cost. Segmented delivery may also create additional site assembly.

10. What is temporary truss bracing?

It is the temporary arrangement used to maintain stability during erection before all permanent restraints and connections are complete. Responsibility should be defined in advance.

11. May a truss be cut or drilled on site?

It should not be altered without approval. Cutting, drilling, welding or relocating connections can change structural behaviour and requires written confirmation from the responsible designer.

12. Are purlins included in a roof truss quotation?

Not always. Some suppliers quote main trusses only, while others include purlins, bracing and connectors. Check every line item.

13. How long does roof truss fabrication take?

It depends on information completeness, drawing approval, material availability, quantity, logistics and site readiness. Request separate periods for each stage.

14. How can two quotations be compared fairly?

Confirm that both use the same drawings, design inputs, material specification and work scope. Add omitted design, connections, transport or erection items before comparing totals.

15. What documents should be handed over?

Depending on project requirements, the package may include final drawings, component schedules, material information, erection instructions, inspection records, approved changes and warranty documents.

An effective prefabricated roof truss RFQ does not attempt to replace engineering design. It gives every bidder the same clear description of the span, roof build-up, attached loads, structural interfaces, delivery limits and erection responsibilities. This makes exclusions visible, improves price comparison and reduces the chance of discovering a geometry, access or scope problem only after fabrication has started.

Before issuing the final RFQ, ask the architect, structural design team, main contractor and roof truss supplier to review the support positions, future equipment, access route, lifting space and temporary bracing arrangement together. Resolve those interfaces before confirming the price and shop drawings.

Disclaimer: Information provided is for reference only. We do not bear responsibility for any inaccuracies or consequences arising from its use.