This House is Assembled With a Screw Gun
A French design firm shows off a house prototype Passivhaus structure made from blocks of foam and laminated veneer lumber
A French design studio has come up with a prototype for a house made from blocks of expanded polystyrene foam insulation, lengths of laminated veneer lumber and not much else.
The Pop-Up House from MultiPod Studio in Marseille is a 1,615-sq. ft. building assembled on site in just four days with nothing more than a screw gun and long screws, according to a blog by Matt Hickman at Mother Nature Network.
The house is designed to meet the PassivhausA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. standard for energy consumption and air tightness, although TreeHugger’s Lloyd Alter wonders whether it would qualify for certification.
Basic shell on the cheap
As the time-lapse video at MultiPod’s web site shows, construction amounts to assembling the precut blocks of foot-thick foam and lengths of LVLs with long screws. Given the low weight of the foam, and the modest size of the LVLs, there’s not much heavy lifting involved, either.
Components are assembled on what look like I-joists rather than a conventional foundation or slab. When complete, the structure consists of two rectangular wings connected by a glass-faced room that would be a living/kitchen area.
MultiPod advertises the cost of the building at $200 euros per square meter, or roughly $26 per square foot, but you’re buying only a shell. While that price includes labor for assembly, it doesn't cover interior finishes, exterior wall sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. , siding, roof sheathing, roofing, electrical work, plumbing, or any HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. equipment.
If you don’t like the idea of using all that foam, other insulating materials could replace it, MultPpod says, including rock wood panels, cellulose, or cork. A variety of roofing options are possible.
You can’t buy the house, at least not yet. MultiPod says it created two prototypes (an office as well as the house) and is looking for manufacturers to develop and market the idea.
Still a lot of questions
Developers say the Pop-Up House concept will meet the Passivhaus test for airtightness, which means air leakage of less than 0.6 air changes per hour at a pressure difference of 50 pascals. The company, however, said by email on March 24 that no blower door tests have been conducted on the prototypes.
Prospective owner/builders might wonder about how the roof and exterior walls are sealed to the weather. Here, MultiPod suggests a variety of options, including an EPDM membrane for a flat roof, and conventional roofing over purlins in cases where the building includes a pitched roof. For exterior walls, the company says, options include fiber cement panels, metal, or even the exterior insulating finishing system (EIFS).
There's also the issue of meeting U.S. fire codes, which prohibit exposed foam on the interior of a building. At least that one would be fairly simple to solve by attaching a fire-rated material, such as 1/2-in. gypsum drywall, to furring strips.
For now, the Pop-Up House is in development. Whether it ever gets to market here remains to be seen.
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