You need a floor package that carries the design loads and leaves workable routes for plumbing and HVAC. Start your floor truss vs I-joist comparison with loads and service routes. Coordinate the structure and services before ordering. Then compare the complete package and installation scope.
Floor trusses provide open spaces between chords and webs. I-joists use flanges and a web, with permitted service openings governed by the product instructions. SBCA describes floor-truss service space, and APA explains I-joist applications and selection.
Draw the service routes before choosing the framing
Ask the plumber and HVAC contractor to mark proposed routes, including the largest ducts, drains, and vertical transitions. Locate tubs, showers, equipment, and major openings on the coordinated plan. Give that plan to the building designer and floor supplier.
An open-web floor truss offers routing opportunities, but every web and connection remains part of the component. Ask the manufacturer to show a usable path for the actual services. An opening in one truss does not guarantee a clear route across the floor.
For I-joists, use the identified manufacturer’s hole guidance. Weyerhaeuser publishes a TJI installation guide for its products. Do not apply that guide to another product or assume that a knockout authorizes a larger opening.
Bring unresolved crossings to the design team before manufacture or installation. Ask whether the route, framing direction, member selection, or ceiling arrangement needs to change. Keep the answer on the plan used by both the crew and rough-in trades.
Compare the two systems as packages
Use this table to compare bids. It does not specify a span, depth, or installed price.
Scroll to read all columns.
| Issue | Floor trusses | I-joists |
|---|---|---|
| Service routing | Confirm open-web paths and any designed chases | Confirm permitted web holes for the exact product |
| Layout | Match truss marks, orientation, and special conditions | Match member series, lengths, spacing, and installation details |
| Supports | Coordinate bearing and reactions with the building | Coordinate bearing, blocking, rim, and connections |
| Site cutting | Obtain direction before altering a component | Follow product-specific cutting and hole restrictions |
| Openings | Include required girders and opening details | Include required headers, beams, hangers, and trimmers |
| Installation | Identify handling, temporary restraint, and permanent bracing | Identify stability measures and all required supporting details |
Ask for the quote’s exclusions beside the inclusion list. Review subfloor, adhesives, connectors, hardware, delivery, and design support as separate lines. Make each bidder identify the drawings and assumptions behind its quantities.
Name who designs and reviews the floor layout
Name the person coordinating the structural system. Then identify the supplier’s layout and calculation scope. SBCA’s delegated design guidance explains why individual truss design and whole-building design are separate responsibilities.
Ask who checks concentrated loads, bearing conditions, openings, and interfaces with walls or beams. Identify who reviews the complete proposed floor package. Write down who answers these questions before releasing the order for fabrication or cutting.
Some suppliers handle both trusses and engineered wood. Builders FirstSource describes layout and design services for these components. Confirm availability and scope with the actual branch. Check the contract for the drawings the supplier will provide.
Use a single revision index for the supplier and building designer. If a wall, stair, or bathroom moves, ask which floor documents change. Have the team review the floor package whenever the architectural plans change.
Check floor performance beyond the open span
Ask the designer to specify strength and serviceability requirements for the planned use and finishes. Request the assumptions behind the proposal. Do not choose a member from the distance between walls alone.
Have the team check heavy items and unusual conditions. Identify tile areas, equipment, partitions, and concentrated loads in the design conversation. Ask which assumptions the supplier has included and which remain the building designer’s responsibility.
Review the LVL beam package where beams or headers support the floor. Confirm that each member’s design and connection information agrees with the floor layout. Leave beam sizing to the responsible designer and applicable manufacturer data.
If a bidder promises a “stiffer floor” or “fewer callbacks,” ask for the specification behind that claim. Ask what the bidder is providing and how installation will follow the accepted design.
Coordinate HVAC design with the floor package
Give the HVAC contractor the available framing zones before duct design is finalized. Ask for the route and space requirements from the system design. Manual J establishes loads; the contractor must also coordinate equipment and distribution.
ACCA describes Manual D as a duct-design method. An open floor system still needs a duct design. Request the planned duct sizes and transitions instead of relying on a request for “some room for HVAC.”
Walk through the route at stair openings, beams, and changes in framing direction. Include insulation and finish space where relevant. Ask who issues a revised drawing when the selected floor system changes the route.
Plan storage and installation for the selected product
Keep the manufacturer’s installation documents with the delivery. Identify the receiving person and the installation lead. Confirm how the package will remain supported and protected until work begins.
APA’s I-joist and LVL handling guidance addresses storage and moisture-related damage. Use the applicable product instructions for the actual arrangement. Ask the supplier about material that arrives damaged or remains exposed beyond the planned construction period.
Weyerhaeuser warns that unbraced TJI joists are unstable. Have the installation contractor identify the required stability measures before loading the floor. Do not use the finished floor’s load capacity to judge whether an incomplete assembly can be loaded.
If the project uses floor trusses, request the corresponding jobsite package. Check that the supplied guidance matches the components. Review temporary restraint and permanent floor details separately with the crew.
Stop service conflicts before they become repairs
At rough-in, ask each trade to check its route against the installed package. Mark unresolved conflicts and contact the responsible designer or manufacturer. A different joist position does not authorize cutting a truss web. Ask the designer or manufacturer how to resolve the conflict.
If a component is damaged or altered, document the condition before concealing it. The truss repair guide explains the reporting process. For an I-joist, use that product manufacturer’s technical support and repair instructions.
Before subfloor and ceiling work close access, confirm that specified blocking, connections, and other required details are complete. Keep the current layout and approved changes in the project record. Give the superintendent one list of open items and who must answer each.
Before accepting the order, request one list of all package documents. List the layout, member schedules, connection details, installation guidance, and outstanding questions. Ask the supplier and framing lead to confirm that they are using the same revision. Keep that list with the delivery record so the superintendent can track down missing sheets.
Where Cercha fits
Cercha helps you identify framing contacts through trade and location search. Supplier profiles list brands, and Messages lets you start a package discussion. Use portfolios and endorsements to assess relevant experience before requesting a coordinated proposal directly.