Site selection
- Site must allow good drainage of ground and surface water. Look for opportunities for solar gain, wind protection and access to utilities.
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Excavation
- Excavate deep enough to allow for four inches of clean stone or sand below the basement slab to provide drainage and evacuation of moisture vapor and soil gasses. Install a poly vapor retarder below the slab and seal all joints and perforations to control moisture vapor and soil gasses (such as radon). One inch (R?5) of extruded polystyrene may be installed under basement slab to keep floor warm and to limit mold growth. When installing radiant floor heating or deep heat, additional levels of sand or insulation may be needed.
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Drainage and footings
- Install drainage tile around the footing slightly below the base of the footing, and have it flow to daylight or to a sealed sump pump. Also cover drainage rock with filter fabric. This prevents the footing from having "wet feet," (footings sitting in water).
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Basement wall
- Place a capillary break (such as ice and water shield) on the footing between it and the basement wall. This prevents the wall from wicking moisture through capillary action and dispersing it into the living space (by evaporation and/or diffusion). Waterproof the foundation wall.
- Use an "elastomeric" coating that is sprayed, brushed, troweled or applied in adhesive mats onto the foundation wall to at least the height of the final grade. Do not cover the openings of the drainage tile with the waterproofing. Waterproofing is not just "damp proofing." Specific foundation types may have alternative water proofing applications.
- Insulate the foundation wall. If insulating the exterior: install two inches (R?10) of extruded polystyrene to the exterior of the foundation. Be sure that the foam covers the entire foundation wall, especially the section of the wall that is exposed above the final soil grade. Foam above grade will need to be covered by a finish material. If insulating the interior: particular attention must be placed on moisture and moisture vapor control.
- Backfill by providing drainage material around the drainage tile and up the foundation wall for a minimum of 18 inches. Final grade must slope at least five percent (or six inches in the first 10 feet) away from the house. Do not backfill until the basement floor and the floor joists and sheeting have been applied, to prevent the foundation walls from moving due to soil pressure. Remember to keep siding a minimum of 8 inches above final grade of the soil to prevent moisture from entering the wood at the floor level.
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Band joist and floors
- Install a seal between the sill plate and the foundation wall. Use a rubber (EPDM) gasket, foam or caulk.
- Insulate the band joist area. Use a minimum of R-10 rigid foam, applied internally or externally.
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Walls
- Install a seal between floor sheeting and exterior wall plate.
- When setting the first floor wall, place an EPDM gasket or heavy bead of structural adhesive under the bottom plate and hold it past the floor sheeting by one inch. This will allow the exterior sheeting on the wall to be flush with the foundation and band joist foam.
- Use energy efficient construction methods in corners and partitions. Using these methods provides cost savings and a more thermally efficient wall.
- Wall insulation should have a minimum R?value of 21. Higher R-values are better. For example, a 2"x6" wall insulated with most insulation material would be between R?19 and R?20 before the sheeting. Application of one inch of extruded polystyrene would raise the R?value to around R?24. Even though various insulation materials may have similar per-inch R-values, installation techniques, air-sealing qualities are essential factors to consider in determining the final insulation effectiveness of the wall. Knee walls and walls that separate a vaulted ceiling area and a flat ceiling area must be treated as exterior walls and insulated and sealed as such.
- Apply a drainage plane (house wrap) to the exterior of the wall sheeting. This very important step prevents moisture from the exterior from traveling into the wall cavity. House wraps prevent air from traveling into the house yet allowing moisture vapor from being trapped and causing damage to the wall. Proper application must be followed especially around doors, windows, and flashing so that water drains to the outside.
- Wood, cement, and hardboard siding should be applied with a space between it and the wall. This "rain screen" provides airspace to allow the siding to dry when it gets wet. Steel or vinyl siding does not need this air space.
- The entire home must have a continuous vapor diffusion retarder on the inside of exterior walls. Sealed polyethylene sheeting, breathable smart vapor barrier, airtight drywall approach or certain foam insulations may be used.
- Openings around doors and windows, receptacle boxes and any pipe or conduit that penetrates the thermal envelope must be sealed to prevent air infiltration. Minimal-expanding foam may be used to seal these openings.
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Windows
- Windows need to have a maximum NFRC U-value rating of .35. Lower U-values are better. Low-e windows are suggested. Consider locating facing windows for maximum solar gain in winter and minimum solar heat gain in summer. Reflective glazing may be available for energy efficiency and privacy.
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Doors
- Exterior doors should be made of wood, insulated fiberglass or insulated steel and should have an adjustable threshold and magnetic weather stripping. There is a difference in insulation values of doors; some are better than others. Refer to U-values for doors with glass.
- The door between house and attached garage must be a fire door as a safety measure. This is state fire code requirement.
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Roof, ceiling and attic
- Roof pitch needs to be 3:12 or greater.
- Add ice and water shield under lower 6 feet of shingles and in valleys.
- Ceiling insulation must be a minimum of R-49. This is approximately 15 inches of settled blown cellulose or 20 inches of settled blown fiberglass. Use a minimum of nine-inch raised heel roof trusses to allow the needed level of insulation over the exterior wall. Seal around all recessed lights below unconditioned space to reduce air infiltration. Approved sealed fixtures are available for insulated ceiling applications.
- Ventilate open attic space to allow moisture-laden air to dissipate. Code requires that one square foot of free-vented opening be provided for every 150 square feet of attic area in homes with continuous ceiling vapor barrier. Half can be in the soffit and half can be at the ridge. The recommended method of ridge ventilation is the continuous ridge vent product that can be shingled over to make it weatherproof.
- The entire home must have a continuous vapor diffusion retarder on the inside of exterior ceilings. Sealed polyethylene sheeting, breathable smart vapor barrier, airtight drywall approach or certain foam insulations may be used.
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Whole house ventilation
- Mechanical ventilation (15 cfm/person) is required through an energy recovery ventilator (ERV) or heat recovery ventilator (HRV). If radon is a concern, ventilate properly from sealed sump pit, in accordance with EPA standards.
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Heating and cooling
- Heat pump systems are recommended for highest efficiency. Ceiling fans may be used to increase comfort and increase energy efficiency.
- Locate no ductwork in unconditioned air spaces. Seal all ductwork joints and connections to reduce air leakage. Use approved sealants only.
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Water heating
- Install electric water heater with 92% or higher energy rating and minimum of 10-year warranty.
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Lighting
- Interior light fixtures need to be high efficiency lighting. Install compact fluorescent bulbs; consider long life bulbs and motion sensors to increase efficiency. When using outdoor lighting, high efficiency fixtures should be considered (e.g. high pressure sodium security lights).
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Appliances
- Consider Energy Star® appliances and check Energy Guide labels when selecting all major appliances (including stove, dryer, refrigerator).
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Wiring, safety and security
- Ground Fault Circuit Interrupters (CFCI) must be installed in required locations. (bathroom, kitchen, basement, garage, near water faucets).
- All wiring must be installed according to the latest electrical code.
- Consider home automation, communication and security when running wires in your home. When wiring, consider future needs for computers, phones, entertainment (such as home theaters and audio/visual centers), and security.
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