structural review of an aging multi-level garage
“Communication and clarity of what is happening is what people are really looking for when we conduct a service for them.”
- Ty Landphair, Structsolve Engineering
Project Overview
A property owner recently purchased a historic duplex featuring a unique structural configuration: a double-car garage constructed above a fully enclosed concrete lower-level space resembling a bomb shelter. Before using the space, the owner needed to determine whether the suspended concrete slab supporting the garage could safely support a heavy vehicle — specifically, their vehicles.
Given the structure's age and the unusual garage-over-basement design, the client sought a targeted structural evaluation to assess the integrity of the slab and determine whether modifications would be necessary for long-term performance.
StructSolve Engineering, LLC, was engaged to perform a non-invasive engineering observation of the suspended garage slab and supporting structural system.
Engineering Assessment
The suspended garage slab system showed structural issues affecting performance and durability. An elevated moisture environment, evidenced by standing water and condensation below the concrete slab and corrugated metal decking, poses a corrosion risk to exposed steel components. A longitudinal crack, characteristic of negative bending stress over the central load-bearing beam, suggests limited
top reinforcement—typical of mid-20th-century construction. This crack allows moisture to infiltrate, exposing the underlying steel to water. Mild surface rust was observed on the decking and beam. While no significant section loss exists, prolonged moisture exposure will accelerate corrosion. Corrective measures are needed to address both the negative bending behavior and the moisture intrusion to prevent further deterioration.
Recommended Preventative Measures
Sealing the longitudinal garage slab crack was recommended to prevent moisture intrusion into the underlying steel. Observed surface rust on the corrugated metal decking and central beam, which required cleaning and treatment with a corrosion-inhibiting coating.
Optional closed-cell spray foam insulation on the underside of the metal decking was suggested, after moisture control and corrosion mitigation, to reduce condensation and improve the environment beneath the slab.
These recommendations collectively aimed to manage moisture, reduce stress concentrations, and extend the service life of the suspended garage slab.
Client Perspective
The client was pleased with the communication throughout the whole process and appreciated how thorough, detailed, and organized the provided report was.
“It was one of the best experiences I’ve had, and that’s coming from an administrative contractor.”
- Alvin Krause, Client
Project Details
Location: Rinard, IA
Client: Homeowner
Service: Express Engineering Service (EES)
Scope: inspection of slab supports and slab integrity
