Forensic Engineers and Consultants

Archive: Construction Defects

Installation of Structural Sheathing on Wood-Framed Structures

The facts presented in this blog lead to an interesting story.  During the heyday of the residential construction boom in coastal South Carolina circa 2005, many General Contractors were forced to go out-of-state to find framers and other subcontractors due to the demand creating a local labor shortage.  It turned out that the state of Texas had excess capacity and availability of framers and carpenters. Many Texas framing crews came to South Carolina to satisfy the shortage.  It soon became apparent that the Texas crews, many of which were from inland locations, were accustomed to installing 4’x8’ exterior wall sheathing with the long dimension vertical, i.e., parallel to the studs.  It is especially important and required that the long dimension be oriented perpendicular to the studs.  Laboratory testing has shown that Read More

Types of and Techniques for Reinforced Concrete Masonry Block Construction

Construction using concrete masonry blocks or units (CMU) is ubiquitous in the United States today, and in fact in the whole modern world.  CMU blockwork is a very versatile and relatively economical building material.  It is naturally strong in compression, but with reinforced, grout-filled cells, it can also withstand large shear, bending, and tensile loads imparted by lateral wind or seismic events.  In this article, I will discuss the various types of CMU designs, as well as terminology, construction techniques, and application uses.

The design of CMU is typically comprised of hollow concrete “face shells” with Read More

Uplift and Shear Restraint Techniques for Residential Structures in Hurricane Wind Zones

Hurricane and Tropical Storm strength wind forces can wreak havoc on wood-framed residential structures.  One of the primary hazards is the negative pressures which can develop on the exterior building envelope when the structure is subjected to the high encircling winds.  These negative pressures act like the suction of a giant vacuum on a dwelling’s roof diaphragm, which produces enormous uplift forces throughout the entire structure.  The leeward walls are also subjected to negative pressures, while the windward walls take the brunt of the positive wind pressures.  The uplift on the roof is caused by what the author dubs “the airplane wing effect”.  In other words, Read More

Structural Issues with Coastal Residential Foundations

From corrosion to site drainage, coastal regions present a host of unique and challenging issues for homebuilders and residential property owners alike.  In this article, issues specific to coastal residential foundation installation and in-service function will be addressed.  “Coastal residential” will refer to single-family homes within AE or VE tidal flood zones for the purposes herein.  These locations typically exist in areas with close proximity to saltmarsh or beachfront, or on barrier sea islands.  Per FEMA, in AE zones, the elevation of the first finished floor must be above the flood elevation for the building site.  In VE zones, the elevation of the lowest horizontal structural member must be above the flood elevation for the site.  Most building jurisdictions also require a minimum of (1) foot of freeboard, or additional space, between the flood elevation and these building features.  As a result of these requirements, coastal residential structures must be supported by either crawl-space or elevated “drive-under” style foundations.  It should be noted that wall-type foundations are prohibited in VE zones, and structures within these zones are required to be supported by monolithic elements such as columns, piers, or piles.  Slab-on-grade type foundations are not permitted in flood zones where the foundation will exist within the flood plain. Read More

Warren Welcomes George Sanford, Structural Engineer

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Warren is pleased to announce that George Sanford, P.E. has joined our team as an engineer specializing in structural issues, building envelope performance, and construction defect investigations.

George brings over 20 years of applied structural engineering experience with a strong background in residential, commercial, and industrial structural design to Warren. Read More

Improper Hearth Extension Leads to Structure Fire

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The fire service affords you the opportunity to witness and observe things that a lot of engineers and even most people do not get the chance to see.  An example of this is the situation where extended elevated temperatures combined with poor construction techniques to result in a structure fire.

I have personally observed several occasions where a structure fire was initiated due to improper construction of the fireplace hearth extension.  The most recent one followed a multi-day cold snap, at least by South Carolina standards.  The thermometer read 17 degrees F as I drove to the call of smoke in a residence Read More

Major Causes of Wood Truss Failures

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Wood truss failures can vary and identifying the cause requires visual inspection as well as a working knowledge of the structural loads and building codes. These truss systems must transfer the gravity and lateral loads to the foundations. Consequently, the framing system and the foundation provide strength and stability for a structure. The most common type of wood-framed construction uses roof trusses, exterior and interior load-bearing walls, beams, girders, posts, and floor framing to resist the gravity and vertical loads. This type of wood-framed construction engages a system of horizontal diaphragms (roof and floors) and shear walls (vertical exterior sheathed walls) to resist the lateral loads. Read More

Construction Techniques to Prevent Water Penetration at Windows

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Windows, and their interface with the exterior walls, are an important part of a building’s envelope that resists the intrusion of water. Most builders take many precautions to protect a house from water damage. One of the most important factors in keeping the water out is the installation of window flashing, a thin material that prevents water from seeping in around a window. Read More

When the Walls Come Tumbling Down… Retaining Wall Basics

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A wall is really boring until it fails. A retaining wall is supposed to hold back soil to either support a structure or keep a space clear. When it fails, both of those roles are compromised. A retaining wall does not have to collapse to fail. In fact, a failure is perhaps better defined as when the wall does not perform as expected. Read More

Stop or I’ll Soot!!!

Fire. Something about fire touches our brainstems…both good and bad!  Uncontrolled fire is terrifying and deadly to be sure.  But the controlled burning of wood at a campfire or in a fireplace in your home almost can’t be beat, to my mind! For that very reason, a fairly common amenity to houses nowadays is the gas log fireplace insert.

When not installed properly, these logs will generate soot. These soot particles can leave the fireplace and meander.  All. Over. Your. House.  Read More

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