February 16, 2011
Houses Fabricated to Order
Custom-Made House (MIT Spectrum, Winter 2011) reports on MIT Professor Larry Sass's efforts to industrialize the automated production of custom housing. In Sass's vision, prospective home owners would choose from house design options online. A computer driven process would then fabricate components to be delivered to the construction site. These precision-fitted could be assemblied without the need for nails or other mechanical fastners.
November 12, 2009
World-Record Wood Structures?
Inhabitat's World's Largest Treehouse Built From Reclaimed Wood is intriguing and worth a look.
As is their post, World's Tallest Wooden Building Planned for Norway.
November 16, 2007
Storm-Resistant Home Design
Home Shapes And Roofs That Hold Up Best In Hurricanes (ScienceDaily, Jun. 21, 2007) reports on a research report from New Jersey Institute of Technology identifying design strategies for homes resistant to high winds and storm-driven funding. Among the findings:
- Hipped roofs with a 30-degree slope are the most resistant to wind uplift.
- Homes thats are roughly square in plan are more wind-resistant that those that are more rectangular.
- Roof overhangs should be limited to 20 inches deep.
- An elevated structure is less at risk from storm-driven flooding.
November 16, 2007 in 05 Wood Light Frame Construction, 06 Exterior Finishes for Wood Light Frame Construction | Permalink | Comments (0)
May 20, 2006
More Really Small Houses
Martin and Bragans' housing system is intended as a mass produced emergency housing system, and was designed in response to the plight of thousands of Gulf Coast residents left homeless by the hurricane disasters of 2005.
September 16, 2005
House of Plastic (ArchitectureWeek, 2005.0914) describes Japanese architect Kengo Kuma's "Plastic House", a small residential structure in Tokyo constructed in large part from glass and fiber-reinforced plastic (there is also loadbearing steel).
According to the article, the appearance and translucency of the 4 millimeter plastic panels are manipulated by varying the materials used for the fiber reinforcing, as well as by the insertion of paper sheets or insulating materials. Fiber-reinforced plastic (FRP) is used in many parts of the structure include for example, decking, cladding, screening, and stairs.
Kuma states, "If I were to describe the architecture of the 20th century with one word, it would be 'concrete'. Its freedom and universality fit the 20th century so well that other local methods of construction were abandoned. Moreover, the strength of the solid mass achieved in transformation from thick liquid substance suited an era that desired monumentality and security of privacy. Therefore to seek for a substitute [material] is not a mere formal proposal but an attempt to suggest a principle of living that replaces the fundamentals of the 20th century — freedom (of course, in the sense of the era), strength, and security."
September 01, 2005
Really Small Houses
Just a quick entry:
Jay Shafer's Tumbleweed Tiny House Company designs for very small houses are wonderful examples of innovative, efficient design with wood light frame construction.
October 03, 2004
Life-Cycle Assessment of Light Wood Construction
The Canadian Wood Council has released its technical bulletin Energy and the Environment in Residential Construction, a comparative life cycle assessment of steel, concrete and wood in residential construction.
According to the bulletin, considering embodied energy, pollution and waste generation, and resources and energy use over a 20-year period, steel and concrete construction have the following disadvantages in comparison to wood construction:
- 12 to 20 percent more embodied and consumed energy
- 15 to 29 percent more greenhouse gas emissions
- 10 to 12 percent more air pollution
- 225 to 300 percent more water pollution
- 7 to 50 percent more resource use
- 6 to 16 percent more solid waste production
Three residential construction systems are compared: wood light frame, light gauge steel frame, and insulating concrete formwork, all in a Toronto climate. The study takes the position that life-cycle analysis provides the most comprehensive view possible of the comparative environmental impact of these systems.
July 04, 2004
Developments In Low-Cost Residential Construction
Concrete Homes Continue to Rule The Roost in Lubbock, Concrete Homes Newsletter, May/June 2004, describes the City of Lubbock, Texas's ongoing efforts to replace substandard and deteriorating homes with new homes built with insulating concrete form (ICF) construction.
The replacement program is part of the city's Affordable Housing Reconstruction Program, which receives funding from federal, state, and private sources. According to the article, ICF constructed homes have proven so energy efficient and disaster resistant that the city no longer accepts bids for conventional wood-frame constructed homes.
NAHB Demonstration Homes
Houses M.A.D.E. for research, Fine Homebuilding, July 2004, describes the National Association of Home Builder's (NAHB) four demonstration houses constructed using materials and methods highlighted in NAHB's 1999 Builder's Guide to Marketable, Affordable, Durable, Entry-Level Homes to Last (MADE).
Innovations demonstrated in these projects include:
- precast concrete foundation walls
- advanced framing methods
- maintenance-free siding and roofing materials
- air-admittance valves (mechanical venting ports used in a plumbing system to eliminate conventional pipe venting)
- CPVC plastic water piping
- standing seam metal roofs
- high-efficiency floor plans
Factory-Built Houses, Fine Homebuilding, June/July 2004, compares pros, cons, and costs of three types of prefabricated home construction technologies: panelized, modular, and structurally insulated panels (SIPs).
For each technology, this full-length article describes the basic systems involved, describes the building process with first-hand accounts and annotated photographs, and provides brief lists of pros and cons. The challenges in attempting to create apples-to-apples cost comparisons between the three technologies are also discussed. Some bottom-line conclusions include:
- Panelized construction offers shortened construction time with few if any limitations on design flexibility.
- Modular construction offers the shortest construction time and greatest potential costs savings, but is more limited in design flexibility. (Except for connecting plumbing, electric, and laying carpet, a house can be erected in as little as one day.)
- SIPs construction offers high energy efficiency and high structural strength, but at higher costs than the other systems featured in this article.
_For additional articles on Lubbock's ICF home building program see Lubbock emerges as frontrunner in concrete home construction, and Rebuilding a Community with Strong, Energy Efficient, Affordable Homes.
_More information on MADE homes is available at Results from the Field: MADE Project Path Field Evaluation Site.
_For more articles on this site related to innovative construction technologies see this site's innovations in project design & delivery category. For another example of modular construction aspiring to quality design and environmental friendliness not previously mentioned on this site, see also The Glidehouse by mkarchitecture.
June 27, 2004
Straw-Bale Construction: A Review of Testing and Lessons Learned To Date, Building Safety Journal, May-June 2004, provides a thorough overview of straw-bale construction methods and capabilities.
Noteworthy points include:
- The material qualities of straw bales are discussed, such as size, moisture content, density, fiber length, and bale condition.
- Wall systems can be either loadbearing or nonloadbearing.
- Straw bales in walls are typically coated with various types of plasters, creating a structural composite. Depending on the plaster type, significant structural strength can be added by this outer finish material.
- Moisture or vapor barrier type materials should not be inserted between the straw bales and the outer plaster finish materials. Plaster should be bonded directly to the straw bales, and the entire assembly should remain breathable.
- Flashings or membranes are recommended at window sills, shower stalls, and top of foundation walls.
- Straw-bale walls should be protected from excessive moisture by generous roof overhangs and foundation walls that keep bales well above grade.
- Straw-bale wall assemblies provide insulation performance in the range of R-27 to R-30.
- Plastered straw-bale wall assemblies achieved fire-resistance ratings ranging from 1 to 3 hours when tested according to ASTM E119. Unplastered bales have exhibited a flame spread of 10 and a smoke development index of 350 when tested according to ASTM E84 (meeting building code requirements for fire-test characteristics of insulation materials).
- Structural tests have demonstrated bearing capacities in the range of 3300 to 4300 pounds per lineal foot, as well as significant out-of-plane and in-plane lateral force resistance (in some cases exceeding the strength of plywood-sheathed light wood framed wall construction).
EBnet provides reports and testing information related to straw-bale construction.
May 17, 2004
Shear Walls for Light Frame Construction
Building Strong Garage Door Walls, Journal of Light Construction, April 2004, describes the APA Narrow Wall Bracing Method for providing lateral bracing for garage wall openings where only short lengths of wall are available for developing resistance to seismic and wind lateral loads.
The relatively new, but increasingly broadly adopted, International Residential Code (IRC) provides extensive guidance on lateral bracing requirements for light wood framed residential structures. Typically, all exterior walls and some interior walls require bracing. Braced wall panels are required at wall ends and at regularly spaced intervals along the length of the wall. Bracing can take various forms such as 1x4 diagonal strapping, diagonal board sheathing, structural panel (plywood or OSB) sheathing, and other materials. Such braced panels are normally required to be at least 48 inches wide.
In the case of garage walls with large openings, there is often insufficient length of solid wall to meet the IRC's standard bracing requirements. In such circumstances, one option is the APA's Narrow Wall Bracing Method.
APA Narrow Wall Bracing Method
In brief, this method consists of the following:
- Fully sheathing the building structure in plywood or OSB panels
- Extending garage header beams beyond the framed opening to the corners of the wall (By extending the headers into the wall framing and providing adequate nailing, a semi-rigid moment frame is created around the garage opening.)
- Special, detailed requirements for stud layout, header straps, nailing, and foundation anchor bolt placement
According to the article, braced wall panels constructed with this method may be as little as 1/6 as wide as they are tall. In other words, panels 16 inches wide may be used for a wall 8 feet tall, or panels 20 inches wide may be used for a ten-foot tall wall.
The article also discusses several noteworthy practical considerations. The braced panels cannot have holes drilled or other penetrations, such as for the mounting of exterior lights; and an unusual degree of accuracy is required in the placement of foundation anchor bolts.
APA's Wall Bracing page provides links to their Narrow Walls That Work technical brochure, and to related information.
Information on Simpson StrongTie's proprietary narrow shear wall solutions is available on their Strong-Wall Shearwall page.