Set-Day Alignment: When Field Shimming Is Needed

A module can be ready for the crane and still meet a foundation that needs attention. Set-day alignment depends on approved bearing locations, foundation elevations, and structural connection details agreeing before the crew releases the rigging.

Field shimming may be part of the engineered installation detail, but it isn't a blanket fix for a mismatch. In modular home installation, the right response depends on what the plans call for and what the crew finds at the supports. Here's how to distinguish an approved adjustment from a problem that needs a stop and design review.

Key Takeaways

• Use shims only when the approved plans or the responsible design professional specify them.
• Check bearing contact, elevation, and module connections before releasing the crane rigging.
• Stop if a section won't align. Identify the obstruction or discrepancy instead of forcing a fit.
• On elevated coastal sites, compare foundation support locations and elevations with the module support plan before delivery.

What Field Shimming Can Address

A shim is an adjustment at a support or connection point. In modular construction, its purpose and location must follow the project's approved details. The crew shouldn't choose a shim arrangement on the spot simply because a module appears out of level or sits differently than expected.

A planned adjustment, not a general remedy

Plans may specify shims as part of the bearing detail, or the responsible design professional may approve them to address a defined condition. In either case, the shim belongs within a reviewed structural solution. Its role is to achieve the support and alignment described in the project documents, not to change where loads transfer through the structure.

That distinction matters on elevated concrete foundations. A column, pier, grade beam, or other support has a planned relationship to the module frame. Changing that relationship can affect bearing contact or structural connections. The guidance for coastal multifamily module placement makes the same point: specified or engineer-approved shims are different from an improvised field modification.

What a shim cannot decide

A shim can't determine whether a foundation is in the right location, whether a support can carry the intended load, or whether a connection detail still works. Those questions belong to the approved plans and the design professional responsible for them. If the condition on site differs from the detail, pause the affected work until the discrepancy has a clear direction.

Set-Day Alignment Starts at the Bearing Points

Alignment isn't just about making two modules look straight beside each other. Each section must land on the support locations shown in the engineered plans, and those supports must meet the intended contact and elevation.

Check supports before releasing the rigging

While the section is still held by the crane, the crew can assess its position against the designated bearing points. The checks should include support contact and the relationships needed for the next structural connections. Once the rigging is released, correcting a placement issue may involve more work and a new lift.

The modular home section placement and alignment process includes checking placement before releasing the rigging. This is also when the team can catch a bearing location that doesn't match the support layout. The crane operator shouldn't be expected to compensate for a foundation discrepancy with a last-second shift.

Check the full structure, not one visible edge

A module's exterior wall can appear aligned even when another part of the structure isn't. Set-day checks need to account for floor systems, roof connections, marriage lines, and structural fastening points. For a multi-section home, accurate placement supports the work of joining the sections and completing their connections.

The foundation setout review compares the completed foundation with the module support plan, including marriage-line supports and concentrated loads. That comparison helps distinguish a local adjustment allowed by the plans from a broader layout conflict.

When Field Shimming May Be Appropriate

Shimming may be appropriate when it's already included in the approved detail or when the design professional approves a specific adjustment. The crew needs a defined location and purpose, not a general instruction to "make it level."

The plans identify the adjustment

Before setting begins, the team should review placement drawings, foundation details, and notes that affect bearing, alignment, and connections. Notes about temporary supports or structural fastening can also affect the order of work. A pre-set review of modular placement drawings helps bring those instructions into the field plan.

If the documents specify a shim detail, the crew can follow it at the identified support location. If they don't, a visible gap or uneven contact should trigger a question, not an improvised material choice or placement pattern. The plans should control how the structure is supported.

The adjustment leaves the structural intent intact

An approved shim detail should address the condition without changing the designed bearing layout or connection approach. The crew still needs to confirm that the module is positioned at the correct support and that the connection details can be completed as planned.

When the specified detail fits the actual site condition, the team can proceed within that direction. If the shim would shift a bearing point, affect a connection, or create an unplanned support condition, the issue needs design review before setting continues.

When Shimming Is the Wrong Response

A shim shouldn't hide a discrepancy between the foundation and the module. If the crew can't tell why the section isn't landing correctly, stop and identify the cause before proceeding.

Look for the source of the mismatch

Possible causes include an obstruction at a bearing point, an elevation difference, or a conflict between connection details. A support may also be offset from the location shown on the drawings. These conditions call for diagnosis, because each one may require a different response.

If the module doesn't align, don't force it into position with the crane. That can damage finished surfaces or conceal a structural issue. The guidance on aligning modules without damaging finished surfaces calls for stopping to identify the obstruction, elevation issue, or connection conflict.

Escalate foundation conflicts

A foundation measurement conflict belongs with the builder lead and engineer. The crew should record the location and nature of the discrepancy and keep the affected work on hold until the responsible design professional provides direction. A field adjustment should not turn into an unreviewed change to structural support.

Clear communication helps the right people respond before the discrepancy spreads to other sections or connections. The set-day issue escalation process distinguishes a measurement conflict from permission to improvise a fix.

Elevated Concrete Adds Coastal Site Considerations

Coastal modular homes often rely on elevated concrete support systems. That makes foundation layout and set-day access part of the same practical plan: the crew needs the correct support locations and a safe way to place the sections.

Review elevations and support locations together

The foundation should be compared with the module support plan before the crane arrives. On elevated work, that review includes bearing points and the supports serving marriage lines or concentrated loads. A discrepancy may affect where a section lands and how its structural connections can be completed.

For projects around Key West and the Florida Keys, narrow streets, nearby structures, overhead utilities, and limited crane positions can constrain the lift. In Fort Myers, Sarasota, Tampa, Naples, and other Gulf Coast communities, site access and ground conditions can also affect equipment setup. These factors make a late foundation correction especially difficult to handle during a lift.

Treat crane access as part of readiness

The set plan should account for the route, staging area, crane position, and ground under the crane's outriggers. Soft ground or vulnerable pavers can affect equipment placement, while overhead lines and tight turning space can limit the lift path. A route problem won't be solved by shimming, but it can delay the set if the team discovers it after delivery begins.

A complete modular home setup connects foundation readiness with the delivery sequence and crane plan. The crew needs enough access to place each module at its intended supports, then complete the structural connections under the approved details.

A Practical Decision Path for Set Day

A consistent decision process keeps a small mismatch from becoming an unapproved structural change. The goal is to resolve the actual condition before the section is released or the next module is placed.

Pause, identify, and document

First, hold the affected placement when bearing contact or alignment doesn't match the approved detail. Identify the location and note what appears different: support position, elevation, obstruction, or connection geometry. Compare the field condition with the foundation and placement drawings.

Next, bring the issue to the builder lead and the design professional responsible for the plans. Keep other work moving only if it doesn't depend on the unresolved support or connection. This avoids treating a decision on one point as approval for other locations.

Resume only with a clear direction

Once the design professional gives an approved correction, the crew can follow that direction and recheck the support, alignment, and connections before releasing the rigging. If the instruction changes the work sequence, communicate that change to the crane operator and the installation team.

Set-day coordination should also make clear who handles foundation questions and who communicates changes to the crew. That's especially useful on multi-section homes, where a mismatch at one support can affect the following placements. The crane should move only when the affected section has a defined path forward.

Frequently Asked Questions

Can the crew add a shim whenever a module sits unevenly?

No. The crew should use a shim only when the approved detail or the responsible design professional authorizes it. An uneven fit can point to an obstruction, elevation issue, or foundation measurement conflict. Identify the cause before adjusting the support.

Should the crane force a section into alignment?

No. If a module won't align at its intended bearing points, stop the placement and find the reason. Forcing the section can damage finished surfaces or obscure a structural discrepancy. The crew should follow the approved direction before continuing.

What should be reviewed before delivery?

The team should compare the completed foundation with the module support plan and review placement notes, bearing locations, and connection details. Site access, crane position, rigging, and the delivery sequence also need coordination. Resolving drawing or foundation questions before the sections arrive helps prevent avoidable delays.

Is shimming always needed on elevated foundations?

No. The project details and actual site conditions determine whether a shim is part of the installation. Elevated concrete supports don't create a universal shimming requirement. The approved plans govern the support arrangement.

Keep Alignment Tied to the Approved Design

Field shimming has a place when it's part of an approved structural detail. It isn't a substitute for accurate foundation layout or a way to force a module into position.

On a coastal set, check the bearing points, foundation elevations, and access plan before the crane releases each section. When the field condition doesn't match the drawings, a clear pause and design direction protect the structure and keep the installation on a sound path.