PATH - A Public Private Partnership for Advancing Housing Technology
PATH Top 10 Techniques
Ready to head down the road to improving the quality of housing? We recommend that you start with the following techniques to improve a home's quality, durability, energy efficiency, environmental performance and affordability. We selected these techniques because they can dramatically boost your ability to achieve these goals.
1. Use Optimum Value Engineering/Advanced Framing
Offers: Material Savings, Time Savings, Energy Efficiency, Less Waste
Optimum value engineering (OVE) refers to framing techniques that reduce the amount of lumber used to build a home while maintaining its structural integrity. OVE results in lower material and labor costs, less construction waste, and improved energy performance for the building. While an advanced framing system can be applied as a whole package, many of its components can be used independently, depending on the specific needs of the project.
2. Use Prefabricated Components
Offers: Time Savings, Durability
[IMAGE: A crane drops a structural insulated panel into place] A wide variety of prefabricated panels can be used in place of conventional framing. Prefabricated panels are produced in the factory, often using computer-controlled equipment that transfers panel-cutting instructions from digital CAD drawings. These panels can be assembled rapidly on-site, cutting cycle time significantly. They provide superior insulation and are often lightweight, making installation easier. Further, they can be designed to resist earthquakes, high winds, debris impact, moisture, and insect infestation.
Other popular prefabricated components include precast concrete walls, open web floor trusses, and panelized wall and roofing systems.
3. Build Overhangs, Especially over South- and West-Facing Windows
Offers: Durability, Energy Efficiency, Comfort
Roof overhangs keep hot summer sun from overheating a home and help protect the home from rain. The larger the overhang for windows or doors, the less frequently moisture problems will occur on exterior and foundation walls. Properly sized roof overhangs over south-facing windows will also block unwanted summer sunlight but allow heat gain from sunlight in winter. For detailed instructions on sizing overhangs to minimize exposure to solar radiation, consult Durability by Design.
The local climate will determine the minimum size of overhangs. As a general rule, the wetter the climate, the larger the overhangs you'll need to install. Use 12-inch eaves and rakes in moderately dry climates, 18-inch eaves and 12-inch rakes in moderately moist climates, and a minimum of 24-inch eaves and 12-inch rakes in very wet climates.
4. Size HVAC Correctly
Offers: Comfort, Energy Efficiency, Lower Equipment Costs
Use the Air Conditioning Contractors of America (ACCA) guidelines for sizing HVAC equipment. Benefits include more satisfied customers and thus fewer callbacks, lower initial and operating costs, longer equipment run times and less cycling, and proper dehumidification during the cooling season.
Use Manual J to estimate heating and air conditioning loads. This will be far more accurate than rules of thumb. Use Manual S to select the proper equipment.
5. Install HVAC and Ducts in Conditioned Spaces
Offers: Comfort, IAQ, Energy Efficiency
Improve energy efficiency, comfort, and health by placing HVAC equipment and ductwork inside the insulated, air-sealed shell of the house. All it takes is a little planning. You can cut heating and cooling costs by as much as $200 for the average home since between 20 and 35 percent of the energy supplied to ductwork outside the conditioned space is lost through air leakage and conduction. Initial equipment costs also may be reduced because system heating and/or cooling capacity, and ducts themselves, can be downsized. Material and installation costs for duct insulation, and in some cases, costs for air sealing ducts, can be reduced or avoided. By placing your HVAC and ducts in conditioned space, you will also avoid drawing dirty or mold-laden air from the attic or crawl space. Use ACCA's Manual D to design ducts to ensure proper air distribution rather than relying on rules of thumb.
6. Install Housewrap Properly
Offers: Energy Efficiency, Durability
Housewrap is often viewed solely as an air barrier, but properly installed housewrap also blocks, collects and channels water that gets past the siding. Improperly installed housewrap, however, is a problem waiting to happen. If housewrap is not lapped correctly, for example, water may drain behind windows.
Because housewraps are designed to allow water vapor to diffuse through them, they are best used in mixed and cold climates. For hot and humid climates, #15 felt paper, which limits water vapor transmission through walls in both directions, is a better choice.
Proper housewrap installation techniques include:
For greater detail, see the Building America: Best Practices Series and PATH's Durability by Design.
7. Flash Windows Properly
Failure to flash correctly is a leading cause of roof and window leaks--and callbacks--so be sure to give windows and skylights the time they're due. Use guidelines for proper window flashing from Building America: Best Practices Series and PATH's Durability by Design.
8. Use Appropriate Air Sealing Details
Offers: Energy Efficiency, Increased Comfort
Air infiltration may contribute to as much as 30% of a building's heating and cooling costs, as well as draftiness, moisture, noise, and dust problems.
Significant leaks may occur near the attic, crawlspace, or basement, and around windows, doors, and chimneys. Plumbing chases, electrical outlets, attic accesses, ducts, and dropped ceilings are other likely suspects.
Perform air sealing before adding insulation. Use caulk for sealing gaps of less than ½ inch. Spray foam can fill small holes, as well as large cracks. Expanding foam will work around windows if the product was designed for this purpose. Use weatherstripping to seal areas with moveable components, such as windows and doors. For larger areas, use housewrap or 15# felt paper to form an airtight seal over the exterior sheathing, and polyethylene plastic to seal complicated leakage areas that may be of irregular shape. [IMAGE: Insulating the attic roof line offers significant energy savings]
9. Insulate to ENERGY STAR Standards, Minimum
Offers: Energy Efficiency, Comfort
Insulate your homes to ENERGY STAR standards at a minimum to increase occupant comfort, reduce indoor and outdoor noise, and lower your customers' energy bills.
10. Use Xeriscaping Techniques
Offers: Water Savings, Time Savings
You can reduce your landscaping time and your customers' water bills through xeriscaping. Disturb as little existing vegetation as practical and choose drought-tolerant native plants. Once established, native plants--plants that have not been imported to the region--are very low maintenance, require few if any fertilizers or pesticides, and demand little additional water. Native plants lists are widely available.
In conjunction with drought-tolerant trees and bushes, rock garden arrangements with creeping groundcovers and succulents can provide height, texture, color, and seasonal variety equivalent to conventional ornamentals. Builders and developers can use xeriscaping in conjunction with other Low Impact Development (LID) techniques to minimize irrigation and landscape-maintenance costs in new subdivisions. Learn more from the PATH publication, The Practice of Low Impact Development.
A version of this list was published in the December 2005 edition of Professional Builder.
Content updated on 3/14/2007
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