Western National Mutual Insurance Co. v. Gateway Building Systems, Inc., 887 N.W.2d 887

Dakota Mill contracted Gateway to construct three large grain bins and integrate conveyors with a pre-existing support tower; Gateway provided steel, concrete, labor, anchors, and rebar but not site preparation or fill gravel.
Subcontractors B & B Excavation and BMS Concrete performed excavation, compaction, staking, and footing work; Gateway conceded staking the center of the first bin but disputed responsibility for the other bins’ locations.
After filling, the three bins began tipping/were unstable; Dakota Mill emptied grain, removed/reattached conveyor/support tower, and pursued remedial work and claims for defective construction and engineering.
Western National (insurer) defended Gateway under a reservation of rights and filed a declaratory-judgment action seeking a coverage determination under Gateway’s commercial general liability policy.
The circuit court granted Western National summary judgment, finding several policy exclusions ("damage to your work," a professional-services endorsement, and "impaired property") defeated coverage; the court relied in part on an expert report submitted by Western National after the summary judgment hearing.
The Supreme Court reversed and remanded, holding material facts remain in dispute (causation, subcontractor involvement, timing of damage) and questioning the admission of the attorney‑filed expert report for summary-judgment purposes.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether the "damage to your work" exclusion bars coverage	Exclusion applies because the damaged foundations/bins are Gateway’s work	Gateway says subcontractors (B & B, BMS) may have caused the damage so the subcontractor exception applies	Reversed — disputed facts on causation and subcontractor responsibility preclude summary judgment on the exclusion
Whether the professional‑services exclusion (engineering) bars coverage	Lack of engineering caused losses, so exclusion applies	Gateway disputes that engineering failure was the ultimate cause	Reversed — causation disputed; summary judgment premature
Whether the "impaired property" exclusion bars coverage for the pre‑existing support tower	Tower was merely incorporated into Gateway’s defective work; exclusion applies unless loss was from sudden and accidental physical injury	Gateway argues the "sudden and accidental" exception may apply and factual issues remain about timing/nature of injury	Reversed — insufficient record and genuine disputes about timing, damage, and loss of use
Admissibility/use of Western National’s late-submitted expert report	Report establishes causation and supports exclusions	Gateway challenges the report’s admission (procedural issue) and disputes its conclusions	Court questioned propriety of attorney‑affidavit with report; evidence submission/competency issues and factual disputes preclude summary judgment

Swenson v. Auto Owners Ins. Co., 831 N.W.2d 402 (S.D. 2013) (summary-judgment review and insurance-policy interpretation principles)
De Smet Ins. Co. of S.D. v. Pourier, 802 N.W.2d 447 (S.D. 2011) (contract interpretation; review when facts undisputed)
Biegler v. Am. Family Mut. Ins. Co., 621 N.W.2d 592 (S.D. 2001) (policy interpretation; plain-meaning rule)
Robinson v. Ewalt, 808 N.W.2d 123 (S.D. 2012) (materiality standard for disputed facts on summary judgment)
Gul v. Ctr. for Family Med., 762 N.W.2d 629 (S.D. 2009) (definition of material factual dispute)
Andrushchenko v. Silchuk, 744 N.W.2d 850 (S.D. 2008) (limits on attorney affidavits and admissibility at summary judgment)
Maryland Cas. Co. v. Delzer, 283 N.W.2d 244 (S.D. 1979) (requirements for admissible affidavits)
Haberer v. First Bank of S.D., 429 N.W.2d 62 (S.D. 1988) (attorney affidavit foundations)