August, 2007
Feature
Inspection News and Views from the American Society of Home Inspectors



Commercial Inspection Tips

RICHARD WELDON, P.E.

Expand your business with commercial building information from Carson Dunlop Weldon

Welcome to Commercial Inspection Tips, a new monthly feature providing technical and business information on commercial building inspections. We’re contributing to the ASHI Reporter with the hope of stimulating your interest in diversifying into the field of commercial building inspections as a way to expand and grow your business.


The Deal on Steel

Properties of steel

Steel can be considered an isotropic material; that is, it is equally strong in all directions. It is effective in both compression and tension and is ideal for resisting movement, combined loads and dynamic loads. It is also flexible and ductile, rather than brittle. 

Steel is subject to corrosion when exposed to moisture and humidity. Some types of steel “weather,” that is, they form a thin layer of rust that protects them from further corrosion.  Steel can also be galvanized (coated with zinc) or painted to help protect it from moisture damage. Since corroded steel occupies many times the volume of uncorroded steel, it is possible for a steel member to appear badly corroded, but to have most of its bearing capacity intact. The remaining cross sectional area is the relevant piece of information.  However, the expansive forces caused by the corroding steel can cause damage to adjacent building materials.

Steel applications
Structural steel can be used for beams, columns, frames and braces. Additionally, steel is used in floor and roof decks and in siding. Buildings with steel structures can be very lightweight and open, and are often designed with curtain walls.

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Steel is usually fastened with bolts, rivets, or welds. Rivets are labor-intensive to install and are more often seen in older steel structures. Rivets are installed when they are quite hot. As they cool, they will contract and secure the connection. Bolts and welds are commonly used in modern buildings. Additionally, wood structures often utilize steel connectors such as post bases and joist hangers. Masonry structures often use steel ties to connect the wythes of masonry together. 

Steel structural sections

Steel for construction projects is manufactured in mills in a variety of standard extruded shapes and sizes. See the diagrams for information about the most common structural steel sections, their nomenclature and their common uses.

Carson Dunlop Weldon & Associates is a leading provider of commercial inspections and commercial inspection training, author of the Technical Reference Guide and the CommQuotTM Commercial Fee Quoting and Proposal Writing System. This article and accompanying diagrams have been taken from a new, not-yet-released Commercial Building Inspection Training Module written by Carson Dunlop Weldon & Associates Ltd. Visit www.cdwengineering.com.