Back on track after unavoidable pre-construction setbacks, the Ultimate Idea House, being built in Little Rock, Ark., has had its share of challenges even before the footings were placed. But delays have been used as opportunities for design improvements that will make the home even more resilient than originally planned.
The concept for the Ultimate Idea House stems from home building podcast Build Your House Yourself University (BYHYU) and is being developed in partnership with RESNET, developer of the HERS Index.
Record rains and flooding in Little Rock were the main culprits stalling the start of construction of this high-performance concept house. The running joke in the area was that it rained only twice in the spring/summer of 2019—once for two months and once for three months.
Countless consecutive weeks of abundant rain culminated in the overflow of the Arkansas River in June. River water infiltrated area homes and sat outside the riverbed for days. These conditions caused a significant postponement to the start of construction of the idea house. This happened not only because of fewer potential working days, but also because subcontractors’ time and attention were diverted from working on bids and new builds to repairing homes damaged by rain and flooding.
The extra rain (and time) sparked the project’s team to consider some design modifications that would make the house more equipped to withstand the region’s wet climate. Little Rock gets 51 inches of rain per year on average. The U.S. average is 38 inches of rain annually. On a site high above and overlooking the Arkansas River, the house will have virtually no chance of ever flooding. But because of its hilltop location, there is a fairly high risk of the site being affected by penetrating, wind-driven rain. As a result, the team added an outdoor storage unit to the jobsite to protect construction materials from downpours. In addition, a rainscreen and a covered entry were incorporated into the home’s design.
A covered entry was not included on the original house plan. However, the construction team is insisting that a covering for the front door be added to the plan to protect the home’s entry from infiltrating rain.
To address potential moisture damage to the home, a rainscreen will be added beneath the stucco and stone exterior cladding. A rainscreen allows any incidental moisture that finds its way through the cladding to escape and dry to the outside. The two-in-one product chosen by the project team combines a rainscreen with a fiberglass lath system used for stone and stucco applications. Using products that combine construction solutions decreases both the labor and time needed for installation, helping to make up for some of the time lost on the project due to the weather.
Along those same lines, the home’s sheathing combines a water and air barrier with continuous exterior insulation, which will not only provides a tight building envelope for this high-performance house, but will also save on labor needs when compared with having to separately install sheathing, a moisture and air barrier, and exterior insulation.
The construction schedule also suffered from waiting several months for the structural engineer’s designs of the foundation, living room mezzanine, and continuous load path. Smaller cities like Little Rock tend to have a limited number of specialized professionals like structural engineers. In times of thriving construction, overdue structural designs are more often the rule than the exception.
However, while waiting for the structural engineer, the team used the time to revisit the original set of house plans. The build team added missing dimensions and construction detail to the plans so subcontractors could more easily interpret and execute the design. The original plan set left room for assumptions and misinterpretations, which would have potentially caused mistakes and slowdowns in the field.
Modifications to the roof design also were made to make it more economical and better suited for the rainy climate. An early quote from the plumber revealed that roof drains for the original four flat roofs would take a large portion of the plumbing budget. Therefore, the majority of the roof design was changed to a standing-seam metal roof. The two largest flat membrane roofs were switched to low-pitched (3:12) metal roofs. This redesign maintains the aesthetic of the house, but works better for the budget and for decreasing the risk of potential leaks. Roof drains for the two remaining flat roofs were replaced with plans for scuppers, which are more economical and easier and quicker to install.
The final pre-construction hurdle was encountered after getting started with the initial excavation for the footings. Although civil and structural engineers had assessed the homesite prior to excavation, not one of them had been able to predict the degree of unstable soil encountered on the north side of the homesite. To address the unexpected soil inconsistencies, the foundation design was changed from columns with wide footings to a retaining wall. The retaining wall is being constructed with concrete block and horizontal and vertical rebar for greater resilience.
As a result of these challenges encountered during the pre-construction phase, the team of this case study house is now better prepared to build a strong, weather-resistant home from which everyone can learn.
The Ultimate Idea House will be scheduled for virtual and in-person tours upon its completion in 2021. The project will also be presented at RESNET’s Building Performance Conference. To follow the construction progress, look for quarterly project updates at builderonline.com, BYHYU.com/ultimateideahouse, or on Instagram @ultimateideahouse.
