In Dallas, Texas, Marc Kleinmann is working on plans for a house which the owner wants to look like the the iconic designs by California developer Joseph Eichler: lots of glass, a low-sloped roof, and roof beams that penetrate the exterior walls to support a broad roof overhang.
That style was all well and good back in the 1950s and ‘60s, but with our keener interest in energy efficiency, Kleinmann wonders in this Q&A post at GreenBuildingAdvisor whether it really makes much sense.
“Don’t know yet if those are going to be structural or not,” he writes of the protruding beams, “but either way I have can see some issues with several large 16-in. beams continuing from interior to exterior.”
He adds that while the beam detail could be designed so they did not actually penetrate the wall, “I can see lots of headaches with that method, too.”
It’s an interesting problem, and it leads to the larger question of aesthetics over practicality in modern architecture: Is the California Modernist style merely a “relic” of the age of cheap oil? That’s the focus of this week’s Q&A Spotlight.
One problem is thermal bridging
As Armando Cobo points out, many architectural styles have included beams that extend out from the house this way. One problem is thermal bridging, which is a path for thermal loss due to the lower R-value of wood versus cavity insulation, such as cellulose or polyurethane foam.
Cobo has several suggestions: First, stop the beams or timber trusses at the outside edge of the wall, install rigid foam insulation over the sheathing and then install faux beams on the outside. “It’ll help you with the thermal bridging at the beams, it solves the moisture intrusion and you will have a better insulated wall overall,” he writes.
“A second option if you don’t want to use exterior foam board could be to stop the beam or timber truss 2 in. from the outside edge of the wall, cut out 2 in. rigid foam to fit, then finish your wall and install the faux beams outside,” he adds.
Yet a third option would be to add a foam band around the soffits and trim with cladding, then install the faux beams on the outside of the house.
“As you can see,” he says, “the object is to break the continuous beam to avoid thermal bridging and moisture intrusion.”
Is the added weight a problem?
Kleinmann, as it turns out, had been thinking of breaking the beams at the exterior walls but was concerned that with a 3-ft. overhang, the solid 16-in. beam tails would be too much weight for the roof.
Cobo suggests installing a couple of nailers between the rafters, gluing the beams to the soffit and toeing the beam-ends into the nailers. If the beams are especially heavy, he suggests drilling up through the middle and bolting them to the nailers with a nut and washer on top. He might want to plug the bottom of the beams to improve their appearance: “a lot of work, but if that’s what your client wants…”
John Brooks offers a a link to details of Eichler designs and says the beauty of the houses is in the way materials were used in a “judicious way.
“I think it would be a ‘faux pas’ to strap on faux beams,” Brooks says.
Keith Gustafson agrees, but for a different reason. With beams spaced up to 96 in. apart, it should be possible to come up with a detail that minimizes thermal bridging. More important, he says, “I can think of structural reasons why the continuous beam is superior, especially with big overhangs.”
The real issue is ‘painful’ design
To GBA senior editor Martin Holladay, the real issue is that architectural schools are traditionally weak on building science, resulting in “these types of painful designs.”
“Beauty is an idiosyncratic concept,” Holladay writes. “But to me, homes with major thermal bridges are aesthetically disturbing. Looking at them hurts.”
He’s not the only one who laments form-over-function thinking resulting in architectural styles that win rave reviews but perform poorly.
“Ahh, the things we do for beauty,” adds Gustafson, “the picture in the post is the 6-in. heel of the architectural world. The beams would not seem to be the biggest source of heat loss by a long stretch. The contortions needed to eliminate them (and keep the look) would seem unwieldy.”
Brooks finds the architecture attractive, but agrees there’s a certain amount of hype in architectural schools and in media that cover architecture, including Fine Homebuilding magazine. “This type of ‘fashion’ is certainly not-so-energy-efficient,” he says, “and not what I would recommend unless I lived in San Diego or Bali.”
James Morgan adds this footnote: “My practice has been faced with attempting to upgrade the thermal performance of a number of these Eichler-style relics from the days of cheap oil. And yes, the thermal bridge is typically the least of one’s worries: the over-glazing and the frequent absence of ANY roof insulation other than the 2-in. thick T&G roof deck are far more consequential.
“The design esthetic stems from the common misapprehension that the best way to integrate interior and exterior spaces is to separate them only by a thin glass curtain wall,” he adds. “It’s past time to get beyond such naiveté and thoughtlessness.”
Our expert’s opinion
Here’s how GBA technical director Peter Yost sees it:
The Eichler designs take me back to Hawaii, where I lived as a kid in the early ’60s. So add Hawaii to the list of San Diego and Bali. But it is downright sad to push any design out of its climate context. Low-pitched roofs, tons of shaded glass, and massive through beams and rafters need to stay put in the mildest of climates. Could you make this design work in another climate? Of course, but unwieldy would be a euphemism.
If we climate-tune our mechanical systems, material selections, and details, why not our overall designs? We have enough boulders to push uphill without adding this one to the list.