I received an email from a friend who sent me a link to a specific program of modular homes. She asked me what I thought of modular homes for San Antonio. The link she sent me was for Indy Mod Homes.

One thing for sure, the concept of building modular homes is having another renaissance period right now, and it’s a very hot topic. Others have tried. You might be familiar with Frank Lloyd Wright’s Usonian Homes. They were intended to be affordable, modest, modular, and even so easy to construct, any able bodied owner might be able to construct it him or herself. In reality, it didn’t really work out that way, but the effort started way back in the Depression years. So the current crop of modular homes is not a breakthrough movement at all. Thomas Edison built a series of concrete homes (some still exist). Sears provided kit homes, and Buckminster Fuller also kicked the idea around a bit with his Dymaxion Homes. If you are not familiar with what a Dymaxion house looks like, imagine combining an Airstream trailer with a hamburger bun. Here is a good link for an overview of Frank Lloyd Wright’s Usonian homes.

In my opinion, the modular examples I’ve seen (mostly in publications), lean toward high-end luxury modernist tastes. As with almost all published versions of residential living, the homes are targeted for upper-middle class and upper class buyers. The examples on the Indy Mod Homes website were in the range of 1400-1800 square feet, which is good, but they start in the $300,000’s, which is not so good. And if you look carefully, not only are the Master Bedrooms modestly sized, but the secondary bedrooms are less than 100 square feet each. Some were ten feet by less than eight feet! Not what I would expect for a home priced at over a quarter of a million dollars.

As you would imagine, I’m one of those guys whose scrutiny radar automatically activates when claims of “green” and “sustainability” are tossed about. Clicking on the “Mod=Green” tab on the Indy Mod website, most of the bullet points refer to the control afforded by constructing the modules in a controlled factory and being able to recycle much of the scrap. That’s all a factor of design, and the same level of recycling can happen at site-built projects too. And they say the site is not disturbed during construction apart from what happens to the site to create the basements (which is not mentioned). And what exactly do they mean when they claim that, “The whole manufacturing process for modular homes is sustainable”? Really? Are they utilizing materials at a rate that would not prevent future generations from doing the same?

They admit that the homes are based on stick construction, so they’re not much different from conventional construction apparently, when it comes to the kind of materials that are used. From what I can tell, modular homes like this represent the offspring of a fling between conventional mass production housing and mass production mobile homes. Only mobile homes are not this luxurious.

I think that what’s needed in San Antonio are affordable, durable, quality (not luxurious), energy/water efficient, climate responsive, healthy homes that are appropriate at all stages of life and mobility. Entire communities could spring up from just a few good examples that can be built here. I feel kind of sheepish wanting to call this kind of home “green” or “sustainable” since those terms have already been widely misused, misunderstood, and corrupted. What I have in mind goes beyond what is now categorized as “green.” It’s going to be a huge challenge to achieve this kind of housing meeting all of the definition.

So, is San Antonio ready for modular homes? Maybe. But not the Indy Mod template. We should strive for better if we try at all. And jury is still out whether off-site fabrication is truly a “green” or “sustainable” advantage over site-built homes. One thing for sure, we need to start with climate responsive design and materials. That’s not new. The earliest builders here, and I mean the native tribes, the Spanish settlers, and even the soon to follow German builders figured it out. The industrial revolution, cheap electricity, and other factors gave all the builders mass amnesia and we generally forgot how to design responsibly. And that’s why we’re looking for energy and water efficient strategies now.

Austin Highway Then and Now  [Click on the title to access the photo]

I cross this bridge almost every day. I found a photo of this bridge posted on “Back in the Day San Antonio” Facebook page and was told the location. I was intrigued since I recognized the location even after the passage of approximately 100 years. Years ago, I came across a map of San Antonio from 1935 and it indicated this bridge was on the primary road between San Antonio and Austin. In the sepia photo, you can see that a car coming in from Austin would approach the photographer and cross the Salado Creek concrete bridge and continue toward the photographer crossing in front of him and disappearing off the right side of the photo. The photo is pointing northeast. On today’s map, that old road, just off the right of the photo is called Corrine today. Corrine can be seen blending into today’s Harry Wurzbach Road leading further southwest toward Fort Sam Houston Army post. This was the 1935 prime road just outside San Antonio on the way to Austin. Today, there’s the Austin Highway which was the main road sometime after 1935 and continued to be the main road until Interstate Highway 35 was completed bypassing all of this on the way to downtown SA. The Austin Highway “new” bridge is shown in the color photo on the left.

Yesterday, I tried to find the spot where the sepia photo was taken and took a shot or two with my phone. Amazed at the way transportation routes and cameras have changed in a hundred years, it was just as amazing to see the old Salado Creek bridge still in use. Who knows the number of countless floods that have completely submerged this bridge over the decades? And still it survives. Granted, the amount of traffic today is dwarfed by the traffic crossing the “new” Salado Creek bridge on the left side of the color photo, but the old bridge is a testament to what may have been one of the first reinforced concrete bridges in Bexar County still in use. If you take the time to cross the bridge on foot, you can see indications of where old railing or road signs were once attached. You can also see in the middle of the bridge places where the reinforcing steel (re-bars) is now exposed to the surface.

The other day, I was listening to one of my favorite podcasts on my daily 12 mile bike ride that always includes this bridge. The podcast is called “99% Invisible” by Roman Mars. I highly recommend this podcast to anyone interested in obscure and fascinating stories about things that have been forgotten or unappreciated. It’s design-oriented and is my favorite podcast. Last week, I was listening to Roman Mars describing an early example of a reinforced concrete tunnel/bridge at the edge of Golden Gate Park in San Francisco called the Alvord Lake Bridge. It may be the first reinforced concrete structure in America and today looks quite neglected, but still functional. Please go to the 99% Invisible website and read or listen to Episode 81 for the story of the bridge, reinforced concrete, and how an extremely large amount of our country’s infrastructure is neglected reinforced concrete structures that need to be maintained or removed as reinforced concrete does not last forever.

Back to the story on the Alvord Lake Bridge, Roman Mars mentioned that an early innovator in reinforced concrete, E.L. Ransome registered a copyright on twisting bars of steel, now known as “rebar” to improve the adhesion of the concrete to the steel. I learned in architecture school that the elegant success of reinforced concrete is dependent on the duet between concrete and steel. First, they bond very well to each other (and interestingly, even a little bit better if the steel has a thin coat of rust) and most importantly, steel and concrete have the same thermal expansion coefficient. In other words, they shrink in the cold and stretch in the heat at the same length per degree temperature! If they didn’t they would quickly break their bond. I don’t want to give you the impression that rust is great. It’s beneficial only in small amounts and only when the concrete is cast with the steel. Once cast, care must be given to insure moisture does not penetrate the concrete or the steel does not have a connection with the ground. If these things happen, rust can become a problem that can lead to the structure’s destruction.

I noticed the exposed reinforcing steel on the old Salado Creek bridge was twisted. It was not easy to determine whether the steel was a twisted square bar or a twisted steel ribbon, but it seemed to relate to what I had heard on the podcast regarding E.L. Ransome’s patent over a century ago. Today’s reinforcing steel is different. Instead of being twisted, today’s rebar features ribs on round steel to provide a good grip with concrete.  I know there’s not much regarding a “lesson” with this post. I was just struck by realizing the age of this old bridge I ride on every day and being reminded about the historic story of reinforced concrete thanks to 99% Invisible and Roman Mars.

At the end of 2012, Richard Seager and others at the Columbia University Earth Institute released a paper describing their findings based on climate trends and forecasting models. The report says that in many areas of the Southwest, including Texas, winter precipitation will decrease through the year 2040. This is particularly problematic for snows in the cascades which is a major source of water for irrigation as well as potable use in California from snowmelt. In Texas, drier winter and spring soils also cause problems due to less surface water and moist soils available for evaporation which in turn provides upper level moisture necessary for rainfall. In summary, the report suggests that Texans should expect about a ten percent drop in precipitation through 2040. We can expect dry years like what we experienced from late 2010 through late 2011. Prudence would dictate that we adjust our use of water and expectation of water sources accordingly. For those of us who are planning to install a rainwater harvesting system, I suggest an increase in both the collection surface area and cistern capacity would be in order. In rural areas, rainwater cistern planning should also design for an emergency fire supression reservoir (which could be the lower section of one of your cisterns) complete with a fitting similar to a fire hydrant fitting that will be compatible with your local volunteer fire department equipment. Droughts are likely to provide ideal conditions for wildfire, so having a fire supression reservoir could make the difference in saving your property.