A recent question from readers has given rise to some thought. The question: Why are concrete slabs the dominant construction method in Santa Fe?
Good question; it made me wonder.
The question came from a reader who was made aware of a water leak by the EyeOnWater app installed in their home. At first just one gallon per hour, it soon grew to 15 gallons per hour. The leak was invisible because it penetrated the dirt under the panels of his house.
A leak detector found the approximate location and it began with jackhammers – through the tiles and slabs, around and through radiant heating pipes, and then deeper into the wet, muddy mess to find and repair the leak. Then the area had to be filled and compacted, the nozzles repaired, a new slab poured and new tiles laid that did not match the existing structure. Ouch.
It wasn’t always like that in Santa Fe. When migrants from the east began building in Santa Fe, they found floors made of rough stone slabs and earth hardened and polished with ox blood. Their “modern” methods laid rough-sawn wooden beams directly on compacted dirt. Within a generation they noticed that rot was occurring even in the arid southwest.
When Allen Stamm began building its post-war subdivisions, the builders knew how to get beams out of the ground. All houses in the quarters of Casa Solana and Pueblo Alegre were built with raised trunk wall foundations and crawl spaces.
In the mid-1960s, with the development of Barrio La Cañada, and later in the 1970s, when Dale Bellamah opened the neighborhoods around Siringo Road, crawl spaces were gone and slabs were everywhere. Nobody seems to know exactly why.
Have wood prices increased and concrete prices decreased? Have ready-mixed concrete plants and mobile concrete wagons suddenly appeared and are competing for the housing boom? Whatever the reason, the transition was complete.
Passive solar pioneers who preached the wisdom of sunlight on heat-storing concrete heat mass intensified the practice. In the 1980s, builders realized hot water pipes in panels that created the sublime comfort of radiant heat and could be enjoyed in rooms where the sun was not shining.
This, of course, began with the risk of water leaks and burst pipes in plates. Polybutylene, Entran II and Kitec are words that make a builder shudder. Fortunately, modern PEX tubing seems to stand the test of time, at least when there are no couplings. If there are joints, elbows or couplings all bets are eliminated which I think will be the problem for the reader with the leak.
Things could change. As beautiful as radiant heat can be, it neither provides the cooling that is required in the case of climatic disturbances nor a healthy, filterable air exchange. Conducted air-to-air mini-splits offer what radiation cannot, and their fully electric power requirements are solar-compatible.
The growing market for modular construction with cranable boxes could also drive the industry back into crawl spaces with raised foundations, since the attempt to drop a finished unit on pipes protruding from a ceiling is a scenario that no building owner would want to consider.
With wood prices going through the roof, one could guess that panels are cheaper. But the actual prices have followed, and the current regulations for under-ceiling insulation and radon protection mean that the differences are negligible. Creeping spaces are also useful on sloping plots, where excavation for flat slabs is rocky and expensive.
The embodied energy of concrete is also problematic.
The simplest insight from today’s conversation: Install the free EyeOnWater app on your water meter.
Kim Shanahan was a Santa Fe
Green Builder since 1986 and Sustainability Advisor since 2019. Contact him at [email protected]