Iano's backfill

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.

More Really Small Houses

HELP Is on the Way (Dwell Magazine, Feb/Mar 2006) describes  Architect Carib Daniel Martin and builder Rob Bragans' disaster relief  HELP (Housing Every Last Person) Housing  prototype.

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.

Plastic Houses

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."

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.

 

 

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.

Developments In Low-Cost Residential Construction

ICF Homes
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

Prefabricated Homes
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.

More Info
_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.

Straw-Bale Construction

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).

More Information
EBnet provides reports and testing information related to straw-bale construction.

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.

Background
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.

More Information
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.

Evocative Wood Shell

Architect Dan Rockhill's Wedding On the Plains temporary wedding reception hall is constructed as a canvass-covered, Lamella truss vault assembled from light wood framing components. Maple flooring, salvaged from a damaged gymnasium floor, paved the bride's path to the alter. The reception area was paved with a temporary 1 1/2 inch concrete slab that was later cut up and removed for reuse. Saplings and tree limbs were used to construct the chapel.

This project is an exemplary study in simplicity of form and economy of material applied to the creation of evocative structure.

Simpson Strong-Tie's New Shake Table

Simpson Strong-Tie, manufacturer of metal framing hardware and connectors, has recently completed construction of a state-of-the-art research facility for simulating seismic and wind loading on light frame wood construction systems. In the Journal of Light Construction (November 2003), Simpson's building systems research and development manager Steve Pryor is quoted as stating that comparable facilities at university-based research labs tend to focus their efforts on heavy concrete and steel structural systems to the exclusion of light wood frame construction systems.

At the time of this writing, a video demonstrating the shake table in action is available on the web site. This short film provides a great illustration of dynamic lateral forces in action and is highly recommended as a lecture supplement.

Lessons from Tornado Damage

APA-The Engineered Wood Association's Midwest Tornadoes report assesses the structural performance of wood framed construction during the May 2003 Missouri tornadoes.

This 16-page report is clearly written and includes many dramatic, captioned photographs illustrating structural failures and their causes. It is particularly useful in gaining an appreciation of the importance of proper connection design and construction in wood light frame construction. The material in this report could make a good addition to a lecture or serve as worthwhile reading assignment for students.

05 - Wood Light Frame Construction Links

This article contains external links to resources on the Web relevant to Chapter 5 Wood Light Frame Construction.

APA Online Library

APA Engineered Wood Association's extensive resources on panel products, engineered wood, and light frame construction.

Canadian Wood Council

Extensive wood construction technical reference information

Details for Conventional Wood Frame Construction [pdf]

From the American Wood Council. One of the best free, all-around references on wood light frame construction available.

Shake Table Test Video

Simpson Strong-Tie's recently completed shake table simulating earthquake forces on a three-story light frame wall system.

Span Calculator for Joists & Rafters

Size joists and rafters in your browser, free, from the American Wood Council.

ToolBase

A service of the National Home Builders Association, NAHB Research Center. This site provides extensive technical information, as well as access to experts for answers to technical questions.

University of Massachusetts, Building Materials and Wood Technology Publications

An interesting collection of articles related to wood as a building material and construction practices related to light frame wood construction.