Builders Beware: The 7 Deadly Sins of Construction Defects

Avoiding the most common construction defects in order to create a safe and secure home site
By Don Neff

What and where are typical construction defects most commonly found in residential buildings? Based on our analysis of hundreds of projects nationwide and the data stream generated by our digital CaptureQA® quality assurance app, there appears to be no single dominant issue. Our primary research shows that three key elements share the blame equally: deviations from architectural plans, deviations from approved materials, and deviations from standard field quality. This raises the bar in finding the root cause, since there is not just one source of failure.

As with any defect, the quicker the discovery and resolution, the lower the cost for all. But it’s not a simple matter of a keen eye and a sharp pencil. There are numerous assemblies that make up a building structure, potentially impacted by construction defects, and some are largely hidden from view. This creates two types of defects: patent and latent. The former are readily observable such as drywall stains from water intrusion and the latter are not, such as below grade waterproofing or foundation failures from poor compaction and/or hydro-consolidation. The statutes of repose for each type are also different, varying from four years to 10, thus driving the time frame for litigation. When litigation commences at year nine for a latent defect, considerable deferred maintenance may have also accumulated over the preceding eight years, varying inversely the diligence of the common area property management.

Water intrusion from windows, walls, and roofs has historically tended to be the leading cause of insurance claim disputes and CD(construction defect) litigation. Water intrusion is often the result of inadequate flashing systems, building wrap choice and installation practice, and complex roofing assemblies. Some of these could be patent defects and some could be latent defects. Equally important, some could be from poorly executed architectural plan details, poor choice in product selection for a particular application (like those made to meet an imposed builders’ budget constraint), or simply from poorly trained installers. While quality has improved in some regions of the US, this overall trend has not changed dramatically and the quality control mission continues. There is also the issue of deferred maintenance on the part of homeowners or homeowner associations that can create an environment and conditions that promote defects.

Our 20 plus years of experience as a 3rd party QA consultant for homebuilders has produced substantial data and insight on construction defects in residential construction and enabled us to identify the more egregious and pervasive issues.

We have identified the following “seven deadly sins” as most common causes of CDL claims. These “sins” require continuing surveillance during the building design, construction and maintenance life cycle. While not necessarily deadly in terms of endangering life, these culprits are deadly for potential damage to a structure, resulting in costly repairs and potential litigation.

Roofing Weather Barrier Not Installed to Specs
Roofing Weather Barrier Not Installed to Specs

Water leakage from any source can result in unhealthy living conditions due to mold growth and damage to interiors. Clipping eaves as a design solution to save construction costs is not recommended as the eaves help protect the walls. In turn, flat roofs with decks over living spaces (functioning like a walkable roof) are a potential water intrusion disaster. While many roof installation defects could be described, the most vulnerable are out of sight, yet not out of mind, and create longer term deterioration. Common among these is roofing “felt” not fully covering the roof sheeting – possibly split, torn, or deteriorated from over exposure – and can be an entry point allowing water intrusion and/or pigeons in the attic (yes, we have had first-hand experience on newly built production homes). Similarly, open gaps at flashing joints or lack of storm collars on plumbing penetrations through the roofing assemblies are also problematic.




Improperly Installed Window Flashing
Improperly Installed Window Flashing

Windows and doors are often the first defects noticed, primarily from water intrusion leaving telltale drywall stains. Hidden defects include: improperly lapped flashing membranes, missing sheet metal head flashing, and failure to properly install flashing at heads, jambs, and sills. All wall penetrations require a flashing system similar to windows. We have also seen incompatible flashing materials, causing one to chemically melt the other. Those deeply recessed windows, currently in vogue with building designers, are particularly problematic if lacking positive sloping sills for effective drainage. Similarly, radius topped windows need extra care from installers to assure proper lapping of the head flashing strips from bottom to top.






Safety is a critical issue in balcony design and construction—whether a two story wood-frame structure in Los Angeles or a 60-story concrete/steel high-rise in Miami. Balconies on four-story, wood-framed podium projects are potentially at risk with the type of hand rail systems selected, choice of flashing metals in gauge thickness and galvanic coating, as well as the UV protection for cold fluid applied waterproofing and final traffic surfaces selected. Positive drainage seems to be an ever-present challenge for lack of sufficient slope on the decks. Water intrusion may thus occur when a balcony or deck is framed with minimal slope or toward the wall plane rather than away. This can further result in moisture intrusion and wood rot problems. Similarly, improper installation of drains or lack thereof can be a contributing factor. Water testing of completed deck assemblies is always recommended. Making sure that decks and balconies are structurally sound is critical. Poorly drawn plan details or missing saddle flashing of cantilevered structural supports can be problematic resulting in rotting structural members. Recall the recent disastrous balcony failure in Berkeley, which killed six students.



Structural components are the bones that support the entire building. The presence of construction defects in these systems may increase the likelihood and extent of structural damage as well as possible injury to occupants. Common structural defects include a variety of issues: missed and/or improperly designed or constructed plywood or OSB shear walls; insufficient edge and field nailing; and missing or inadequately installed drag straps, hold downs, and various other connection hardware. Similarly, failure to properly design and construct the required load paths from the foundations, to the walls and the roofing members is a recipe for disaster when mother nature’s fury strikes with earthquakes, tornadoes, and hurricanes

For Type I and Type II building construction, there are additional critical assemblies such as those in below-grade parking structures that have to be fully and carefully examined. These include blindside waterproofing assemblies and sub-slab methane barriers per recommendations of the all-important geo-technical/soils reports specific to that project.



missing exterior
Missing Exterior

Brick, rock, aluminum, wood, vinyl, and stucco are typical exterior cladding systems and serve an important purpose of protecting the actual building structure while giving a home aesthetic appeal. However, improperly constructed siding can result in construction defects and water intrusion that can also be difficult to find and repair. If installation deficiencies allow water to enter through or behind the exterior, it is problematic for the structure’s interior, causing further defects such as mold, cracking, odor, warping, and wood rot. Recent advances in building science have helped building product manufacturers develop cladding systems with vented drainage planes integral to the wall system. The water may get in, but it can still get out.





The structural integrity of a home can be compromised if foundations and concrete slabs are defective. Defects in foundations and slabs can result from either horizontal cracking and vertical displacement or from improperly mixed concrete (e.g. too much water in the design mix) that can lead to weak concrete with high porosity which is more vulnerable to vapor transmission, and damage to structural embedments from soluble sulfates in the native soils. The physics of moisture movement due to vapor pressure differentials is also an interesting scientific phenomenon which can lead to damaged interior finishes such as various flooring systems, as well as allowing radon and/or methane to invade the home. Proper pre-cautions can be taken to minimize these problems.



Tears in HVAC
Tears in HVAC

Because they are installed by professionals who are trained, tested, and licensed, Mechanical, Electrical, and Plumbing (MEP) designs and installations are somewhat less prone to deficiencies. Nevertheless, construction defects do occur and can cause life-safety issues, as well as substantial monetary damage. For the most part, these defects such as improper installation of electrical wiring and plumbing are hidden behind walls and ceilings, under floors, and are difficult to find and repair.
Equally important to HVAC installation is the design of these systems for interior moisture management. Perhaps more critical in hot and humid climate regions, without adequate attention to architectural detailing, interior moisture build-up in ceilings and attics can rot away structural components as quickly and easily as will exterior moisture conditions. The homebuilding industry is constructing ever tighter building envelopes, driven by energy conservation requirements. Prudent builders will engage system designers to not only address their mechanical systems for heating and cooling but consider the adequacy of their active and passive ventilation systems. As occupant behavior also drives building performance, more diligent analysis through building science is finally catching on with a goal of minimizing future building system defects.

As builders prepare for California’s energy conservation mandate of net-zero that goes into effect in 2020, we are now more focused on issues related to improperly installed insulation. The standards have been raised and we’re moving towards rigid exterior foam insulation. It appears that most builders aren’t always allocating enough time and resources to ensure that interior fiberglass batt insulation is done correctly, thus creating interior wall convective air flow loops, and resulting in poor energy conservation and more energy usage and expense for the homeowner. As important as it is, insulation should be installed by skilled and experienced tradesmen who know the thermodynamic basics of insulated wall systems.

When it comes to construction, builders, developers, and contractors face many issues today such as the current lack of qualified, experienced tradesmen due to the demand for these workers. In dealing with these challenges, we believe the importance of technology in the building industry will continue to grow and play a bigger role in the construction process along with that of 3rd party professionals who provide the necessary due diligence, quality assurance, and deep analysis to ensure that the job is done right the first time.

Don Neff is the President/CEO of LJP Construction Services. He may be reached by visiting

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