The Nashville housing boom has its blunders

A new construction trend is causing significant problems for some homeowners

  • In this case, house wrap was cut back to reveal the door’s top plate and was a source of moisture intrusion.
  • Thin trim coil metal was used to terminate the balcony’s membrane to the support post, which significantly contributed to moisture intrusion.
  • The contractor chose to install a through-wall scupper into a small gutter with no face plate.
  • This wall tie was caulked to prevent moisture intrusion in the wrong location. Leaks were coming in from around the corner and above the sealant.
  • This area of moisture intrusion resulted in a lawsuit settlement
where attempted repairs for poor metal coping detail had failed. Excessive sealant was applied.
  • Edge metal blew off because of improper securement.
Metal was fastened to the deck rather than flashed into
the low-slope roof system.

Nashville, Tenn., has become host to a growing fad for split-lot development: the infamous “tall and skinny” architectural style of residential construction. These buildings are found huddled together throughout the city, side by side, typically 10 feet apart.

The model is quite simple. First, a historically single-family lot with one existing residence is demolished in an increasingly popular neighborhood. On that same lot, two similar—or, in many cases, mirrored—three-story single-family residences are built side by side. The new “tall and skinnies” are wood frame construction with about 3,000 square feet of living space and tend to feature rooftop patios and balconies.

Proponents of these constructs stand to reap tremendous returns on investment from these new properties. Where once a $170,000 single-family home stood, now two nearly identical $500,000 to $1 million homes stand. Nashville’s housing boom is the result of its relentless popularity, gaining roughly 85 new residents per day based on Census Bureau statistics. Nashville is ranked seventh in population growth between Denver and Charlotte, N.C.

Many of these homes are likely well-built with sound construction plans and exterior envelope details. But in some cases, the glamour of new construction and excitement of the Nashville skyline are steadily eroded by mounting maintenance issues, workmanship claims and moisture-intrusion events. What follows for the owner is a long list of errors spanning consecutive years of turmoil and service calls.

I have inspected numerous split-lot homes at various stages in lawsuits against builders with countless errors. I have supplied investigative reports in concert with expert engineers, architects, lawyers and general contractors. The findings are consistent: Market demand exceeds the availability of skilled contractors, which leads to low-quality construction. There is a clear absence of professional design involvement and precision that puts entire projects and occupants at risk.

To maximize useable space and consumer appeal, rooftop patios are a critical design feature of this building design. To accomplish this, residential roofing contractors are being tapped for low-slope roof system installations with neither manufacturer warranty requirements nor design details in building plans. To decrease overall project costs with the inclusion of a rooftop patio design feature, wood frame patio decks are built over these newly installed and noncompliant “roof patio systems,” further complicating their serviceability.

Picture a low-slope roof system with a wood frame deck built on top of it that would be similar in size and quality to something you’d find in an average residential backyard. The result is a final construction project based on loosely conjured specifications that focuses mainly on interior finishes and overall marketability and features nonspecific design details for hard-to-flash areas. These areas are then subjected to the interpretations of subcontractors and project managers of varying experience. It’s important to note a majority of legal cases I’ve been involved with are new construction, split-lot homes that are less than 5 years old.

Common errors

The primary areas of concern I have witnessed relate to roof assembly and ventilation. With the omission of attic space, ventilation takes a back seat in the interest of more living space and rooftop patio space. Opting for taller or vaulted ceilings carries inherent risks that are not new to roofing contractors, such as condensation and organic growth when air intake and exhaust are limited. Although the buildings may meet code requirements, which are the minimum legal requirements for construction, they do not address code ambiguities.

The topic of ventilation and condensation in unvented attic space far exceeds the scope of this article, but it is a subject not unique to Nashville but particularly endemic regarding Nashville’s climate zone.

Although the 2012 and 2018 editions of the International Residential Code® mention the importance of ventilating and preventing condensation within vaulted attic space on steep-slope applications, it is not mentioned in the 2012, 2015 or 2018 editions of the International Building Code® or IRC with regard to low-slope roof systems. But NRCA Guidelines for Condensation and Air Leakage Control states: “In situations where interior humidity conditions are expected to be relatively high, or in very cold climates, building designers need to consider measures for preventing condensation accumulation in low-slope roof systems. These include the following:

  • Dehumidify conditioned space
  • Ventilate the interior space
  • Use an air barrier to control water vapor transport via air leaks into the roof system
  • Use a vapor retarder to control water vapor diffusion into the roof system from the building’s interior
  • Seal and insulate roof penetrations”

This is important to note because many of the tall and skinny designs I’ve seen feature an insulated, unsealed, unventilated air space without vapor retarder or air barriers. To make matters worse, the design also will typically include a parapet wall, which can be common and recurrent sources of moisture problems. This is primarily a result of improper air and moisture regulation in the overall design. I contend two things with regard to ventilation in these roof systems.

  1. These are known conditions proven to be problematic in low-slope roof systems with regard to ventilation.
  2. It is eerily absent from the code standards regarded as the minimum requirements for design compliance.

My secondary concerns lean heavily toward doors and windows. These new houses most often face west or southwest for sweeping sunsets of the Nashville skyline or rolling Tennessee hills. However, they also tend to feature inward swinging doors and poor flashing details that do not accommodate driven rain from the same direction. Tennessee is notorious for acute weather patterns. Nashville received 52 inches of rainfall in 2020 compared with Seattle’s 43 inches of rainfall. These two conditions are a recipe for disaster when coupled with poor flashing details. It goes without saying these details in new construction regarding doors and windows are not unique to tall and skinny construction; however, they are particularly prevalent in the buildings I’ve inspected of this type.

Other errors I have witnessed include the absence of soldered drainage pans beneath doors and windows, poor penetration details and abysmal architectural sheet-metal work. These items are the result of low-quality installation.

A seasoned contractor would know from experience what details work in direct relation to the length of the material warranties, but seasoned companies often are beaten out of projects based on low bids alone regardless of credentials.

It should be said even if a building of this type has a complete set of building plans that illustrate specific design details in hard-to-flash areas, the plans often state “as per manufacturer’s recommendations” or “per codes,” which virtually guarantees poor execution.

In addition, many subcontractors are on tight deadlines, rushing from job to job and unable or unwilling to coordinate among various trades, resulting in continual start-and-stop scheduling as well as a tunnel vision approach to their part of projects rather than viewing themselves as part of a larger system. As we all know, the building envelope is a complex system intended to work as one, yet when individual aspects of a project are left to an unexperienced subcontractor’s discretion, the results can be disastrous.

How to avoid errors

Before getting into the specifics of how to avoid these calamities, it’s important to make a distinction: This is not a condemnation of a particular building style, the contractors who accept the work or the prospective buyers. I only aim to educate and arm contractors and consumers in the interest of public health and wellness. No new homeowner wants to be displaced from a home because of leaks and mold growth, paying for all the associated expenses out of pocket. And no contractor wants to be tied up in legal proceedings awaiting settlement or arbitration and losing focus on active projects. Following are some ways to identify problems as they arise.

Scope of work

I always tell homeowners to seek a clear scope of work. A submitted proposal for contract work should be complete and in sequence and should specify which manufacturers were used for building materials. This will help ensure the paperwork will keep everyone honest in the event of a claim. And if a homeowner has any concerns, he or she can always check the manufacturer’s website for installation instructions and warranty requirements.

Also, homeowners should request that any building contracts state direct project management is required daily by a competent person and progress reports are submitted at least a couple of times per week. Reporting will keep everyone’s eyes on the ball throughout the project and sends a clear message a project has been thoroughly documented from start to finish.

Follow the plan

Homeowners and subcontractors should request a set of the building plans. The plans should include details that take the entire building envelope into account. In addition, it is important a skilled design professional is involved in the design and construction of this type of home. Plans will help a subcontractor verify a build in progress and check details as they are being installed and after to verify the plans were followed. In addition, a subcontractor should ensure all critical tie-in areas are addressed according to mockups that remain on-site until the project is complete. This means doors, windows, through-wall flashing, base flashing tie-ins, and copings or other architectural sheet-metal features as needed. This is to ensure everyone on the job can see at a glance whether the details are correct or incorrect. A set of plans also should be available on-site at all times and stored in a highly visible and weather-resistant area of the building such as a mounted display case for reference.

Make the investment

This is one of the most important aspects of any successful project. Everyone knows the old adage “an ounce of prevention is worth a pound of cure.” There is a clear absence of professional services in terms of architectural and engineering involvement during the planning phases of these building designs. This is evidenced by the lack of clear and specific design details in building plans.

Another cautionary quote I like is what art critic John Ruskin said more than a century ago: “It’s unwise to pay too much, but it’s worse to pay too little. When you pay too much, you lose a little money—that’s all. When you pay too little, you sometimes lose everything because the thing you bought was incapable of doing the thing it was bought to do. The common law of business balance prohibits paying a little and getting a lot—it can’t be done. If you deal with the lowest bidder, it is well to add something for the risk you run, and if you do that, you will have enough to pay for something better.”

Consumers must fight the urge, almost daily, to be lured by what is cheap, quick and easy. This is especially true in construction. Professional fees are typically less than 2% of a building’s total life-cycle cost yet they can have a profound effect on the other 98% of a building’s overall cost. Taking this metric into account, the cost of design professionals on a project pales in comparison to the potential cost of legal fees and repair work that follows a claim not to mention doctors’ fees if mold is involved, displacement costs, abatement, multiple expert witnesses and replacement of any damaged personal items.

If possible, subcontractors should ensure load calculations have been thoroughly evaluated to accommodate rooftop patios and open floor concepts don’t jeopardize the structural stability of a building’s overall footprint. This condition was reported following an EF-3 tornado in middle Tennessee in March 2020. An interview with residents and code officials revealed the construction of the homes was quick and code-compliant. However, the tornado sheared two adjacent homes at the exterior wall, collapsing the roof to the foundation like an accordion. This was attributed to an open floor concept.

Protect the investment

Homeowners should inspect warranties to verify the workmanship and long-term viability of their investments. Potential buyers should make sure to factor into the home inspection costs infrared scans of the roof system, ceilings and exterior walls to confirm the presence or absence of moisture. If you are a subcontractor engaged in constructing these homes, invest in the equipment to perform your own scans and include them as part of your workmanship warranty coverage to protect yourself and the owner. If you identify a moisture issue within the warranty period, you have caught it before it spreads and causes a much bigger problem. The earlier you identify flaws, the less cost you incur to fix them.

Lessons learned

It’s important to reiterate I do not condemn tall and skinny construction. Rather, I condemn uncommon building styles receiving less than common attention to detail. It has been my experience and the experience of my colleagues that this specific building type is particularly susceptible to building errors and moisture intrusion. Its popularity offers tremendous ROI for builders and owners as well as additional square footage in the form of rooftop patios and balconies.

The point of contention comes with shoddy workmanship, vague planning, minimal project oversight and the virtual omission of necessary designer involvement. Builders and buyers should have a deep appreciation for the efforts of licensed design professionals. Their formal training and attention to detail carries with it a weight that far exceeds any cost concerns. Their involvement must be viewed as an investment rather than an expense. This is especially true for tall and skinny buildings. Trust the professionals involved, but more important, trust the process and begin with a good plan.

Nick Warndorf is director of consulting services for Don Kennedy Roofing Co. Inc., Nashville, Tenn.


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