Relation-Back Permits Late Joinder of Engineers for Negligence Where Inherently Dangerous Excavation Creates Vicarious-Liability Unity of Interest—But Not for NYC Building Code § BC 3309.4 Strict Liability

1. Introduction

In Crossbay Assoc., LLC v Singh (2026 NY Slip Op 03941), the Appellate Division, Second Department reviewed whether a property owner-plaintiff could amend its pleading—after the statute of limitations had run—to add an engineering firm and its principal (Rizwan Abdus Salam P.E. Consulting Engineer, P.C., and Rizwan Abdus Salam) as new defendants. The underlying dispute arose from excavation work allegedly performed on property adjacent to the plaintiff’s building, purportedly without adequate support of excavation (e.g., shoring), resulting in a partial collapse of the plaintiff’s structure.

The key procedural issue was whether the proposed defendants could be added under CPLR 3025(b) using the relation-back doctrine. The substantive split concerned the nature of the claims: (i) negligence and gross negligence versus (ii) strict/absolute liability tied to New York City Building Code (Administrative Code of City of NY, tit 28, ch 7) § BC 3309.4.

Parties and posture

  • Plaintiff-Appellant: Crossbay Associates, LLC (owner of the damaged property).
  • Original Defendants-Respondents: Inderpal Singh, Sarbjit Singh, Mike Singh, Tejinder Singh (adjacent owners) and AT-SAF, Inc. (alleged general contractor), and Sikander Singh.
  • Proposed Defendants / Nonparty-Respondents: Rizwan Abdus Salam P.E. Consulting Engineer, P.C., and Rizwan Abdus Salam (alleged excavation/foundation engineering services provider).

2. Summary of the Opinion

The Second Department modified the Supreme Court’s order. It held that the plaintiff satisfied relation-back and could add the proposed defendants for the negligence and gross negligence causes of action, but not for the strict liability claim under § BC 3309.4.

  • Granted: Leave to amend to add the engineer defendants as to negligence and gross negligence.
  • Denied (affirmed): Leave to amend to add the engineer defendants as to strict liability under NYC Building Code § BC 3309.4.

3. Analysis

3.1 Precedents Cited (and how they drive the result)

Relation-back framework

The court anchors the analysis in Buran v Coupal, 87 NY2d 173, which is the leading Court of Appeals authority articulating New York’s modern relation-back approach and its policy balance—permitting late joinder where the new party had adequate notice and is sufficiently aligned with the original defendants. The Second Department then quotes the familiar three-part test as stated in Bumpus v New York City Tr. Auth., 66 AD3d 26:

  1. Same conduct, transaction, or occurrence;
  2. Unity of interest between original and new party;
  3. New party knew or should have known that, but for a mistake as to identity, it would have been sued.

“Unity of interest” and vicarious liability

The opinion collects several Second Department decisions clarifying unity of interest:

  • Mileski v MSC Indus. Direct Co., Inc., 138 AD3d 797 and Mitzmacher v Bay Country Owners, 211 AD3d 1025: Unity exists when parties “stand or fall together” such that a judgment similarly affects both.
  • Desiderio v Rubin, 234 AD2d 581 and Ragusa v Drazie's Farm II, LLC, 226 AD3d 836: If one party may assert a defense not available to the other, unity is lacking.
  • Bisono v Mist Enters., Inc., 231 AD3d 134 and Cedarwood Assoc., LLC v County of Nassau, 211 AD3d 799: Vicarious-liability relationships typically create unity because defenses align.

Independent contractor nonliability—plus the inherently dangerous exception

To determine whether the original defendants could be vicariously liable for the engineers’ alleged negligence (which would support unity of interest), the court relies on the independent-contractor baseline rule and its exceptions:

  • Mery v Eginger, 149 AD3d 827, affd 31 NY3d 1068, quoting Kleeman v Rheingold, 81 NY2d 270: As a general rule, one who retains an independent contractor is not liable for the contractor’s negligence.
  • Brothers v New York State Elec. & Gas Corp., 11 NY3d 251 and Kleeman v Rheingold, 81 NY2d 270: This general rule is subject to exceptions, including where the work is inherently dangerous.
  • Klein v Beta I LLC, 10 AD3d 509 and Hixon v Congregation Beit Yaakov, 57 AD3d 328: The court cites these as support for treating the pleaded excavation circumstances as sufficient (at this stage) to invoke the inherently dangerous exception, making vicarious liability plausible.

Notice/“mistake” prong

For the third prong, the court cites Marrone v Miloscio, 145 AD3d 996, for the proposition that relation-back can apply where the new defendant knew or should have known it would have been sued but for a mistake about proper identity. It also references Brunero v City of N.Y. Dept. of Parks & Recreation, 121 AD3d 624, as a general exemplar of granting amendment where relation-back is met.

Strict/absolute liability under Building Code § BC 3309.4 and why unity fails

The strict-liability analysis turns on who the statute targets—“the ‘person who causes’ an excavation to be made.” The court quotes American Sec. Ins. Co. v Church of God of St. Albans, 131 AD3d 903, quoting 492 Kings Realty, LLC v 506 King, LLC, 105 AD3d 991, on the reach of § BC 3309.4.

It then relies on:

  • Reiss v Professional Grade Constr. Group, Inc., 172 AD3d 1121, abrogated on other grounds by 211-12 N. Blvd. Corp. v LIC Contr., Inc., 186 AD3d 69: Strict liability under this code provision attaches to the responsible excavating/causing party; others may have distinct defenses.
  • 87 Chambers, LLC v 77 Reade, LLC, 122 AD3d 540: Supports the conclusion that parties outside the “owner/actual excavator” lane are not similarly situated for strict liability.

Applying these authorities, the court finds the engineers were not owners of the adjacent property and not the excavation contractor who performed the work; therefore, they possessed defenses not shared by the original defendants. That defeats unity of interest and relation-back for strict liability.

3.2 Legal Reasoning

(a) CPLR 3025(b) + an expired limitations period triggers relation-back scrutiny

The court treats the proposed amendment as time-barred absent relation-back. Thus, the amendment does not rise or fall on CPLR 3025(b)’s usual liberal standard alone; it depends on whether the new claims against the new parties are deemed timely.

(b) Negligence and gross negligence: unity of interest satisfied via plausible vicarious liability

The decisive move is the court’s acceptance that the pleadings alleged “inherently dangerous” excavation activity (excavation without support causing a collapse). If the work is inherently dangerous, an entity that retains those performing it may be vicariously liable notwithstanding the independent-contractor rule. Once vicarious liability is in play, Bisono v Mist Enters., Inc. and Cedarwood Assoc., LLC v County of Nassau support treating the parties as united in interest because the litigation posture and defenses substantially align: the original defendants’ liability on these claims could be derivative of the engineers’ negligence, and the defenses would tend to “stand or fall together.”

(c) Strict liability: unity of interest fails because the statute targets different actors

By contrast, § BC 3309.4 strict/absolute liability is not analyzed like ordinary negligence allocation. It is actor-specific: it imposes liability upon the “person who causes” excavation. Because the proposed engineer defendants were not alleged to be the owners or the actual excavators, the court concludes they can advance different defenses on the strict-liability claim than the owners/contractor defendants. That divergence defeats unity of interest under Desiderio v Rubin and Ragusa v Drazie's Farm II, LLC.

3.3 Impact

Practical pleading consequences in construction/excavation loss cases

  • More viable late joinder of design professionals for negligence: Where excavation or similar construction work is pleaded as inherently dangerous, plaintiffs may use relation-back to add engineers/consultants after limitations, provided they can show the three prongs—especially unity of interest through a plausible vicarious-liability pathway.
  • Strict-liability claims remain narrower for relation-back: For NYC Building Code § BC 3309.4 claims, this opinion reinforces that unity of interest is harder to establish beyond the “person who causes” excavation (commonly owners and excavating contractors). Design professionals may fall outside that strict-liability identity, giving them distinct defenses and blocking relation-back.
  • Claim-by-claim relation-back analysis is mandatory: The court’s split result underscores that unity of interest can exist for negligence while failing for statutory strict liability in the same case. Future courts and litigants should treat relation-back as cause-of-action specific.

4. Complex Concepts Simplified

  • CPLR 3025(b) (leave to amend): A rule that generally allows parties to amend pleadings with permission; courts often grant leave unless there is prejudice or the amendment is plainly meritless. But if the statute of limitations has expired, the amendment must be “timely” via relation-back.
  • Relation-back doctrine: A doctrine that can treat claims against a newly added defendant as if filed on the original filing date, but only if the three-part test (same occurrence, unity of interest, and knowledge/mistake) is satisfied.
  • United in interest: Two parties are “united” when their legal interests are so aligned that a judgment against one effectively determines the outcome against the other—often because one is vicariously liable for the other and defenses are essentially the same.
  • Vicarious liability: Liability imposed on one party for another’s wrongdoing due to a legally recognized relationship (e.g., employer/employee, or certain nondelegable duties/exceptions involving independent contractors).
  • Independent contractor rule and “inherently dangerous” exception: Normally, hiring an independent contractor insulates the hirer from liability for the contractor’s negligence; however, if the work is inherently dangerous, the hirer may still be responsible.
  • Strict/absolute liability under § BC 3309.4: Liability that can attach without proving negligence, typically focusing on whether the defendant falls within the category of persons the statute makes responsible (here, the “person who causes” the excavation).

5. Conclusion

Crossbay Assoc., LLC v Singh sharpens New York practice on late amendments in construction-collapse litigation by making two points clear. First, when inherently dangerous excavation is plausibly alleged, relation-back may permit adding engineers as defendants for negligence-based claims because vicarious-liability principles can create unity of interest with original owner/contractor defendants. Second, that same unity may not exist for NYC Building Code § BC 3309.4 strict liability, which targets the “person who causes” excavation and can afford different defenses to non-owner, non-excavator professionals. The opinion’s claim-specific approach provides a roadmap: plaintiffs should plead and prove relation-back elements per claim, while defendants should focus unity-of-interest objections on differences in statutory role and available defenses.

Source: Crossbay Assoc., LLC v Singh, 2026 NY Slip Op 03941 (App Div 2d Dept June 24, 2026).