Ever since Greg Buyan became construction manager of Habitat for Humanity Mississippi Capital Area about a year ago, the organization has been looking at the methods and principles it uses in the homes it builds.
The nonprofit’s first goal is to ensure that its homes are affordable, safe and healthy, sustainable and responsible (less waste, environmentally friendly such as bamboo or stained concrete floors, and energy efficient such as CFL bulbs).
The secondary goal is to use building materials and products that are easily purchased, while utilizing practices that make our houses more efficient — so heating and cooling savings can be passed on to homeowners.
“We’re not trying to reinvent wheel,” said Buyan. “We taking simple processes and using good principles and practices. A lot of the funding is done my grants and to satisfy those grants, homes must be built to standards, one of which is the Entergy Star 3.0”
Among new practices and principles that HFHMCA is utilizing:
» Reducing the square footage to 980 (3 bedroom, 1 bath) while maximizing the living space. For example, moving the mechanicals (tankless water heater and furnace) to the attic will save space. Habitat said it wants to make a small house feel as big as possible by having an open living, kitchen and dining area.
» Adopting a 40-foot long by 24-foot wide house plan to reduce building material waste. On the sidewalls, it will utilize 10 sheets of 4-foot by 8-foot plywood. On the plywood decking, it will use an 8-foot piece and a 4-foot piece. By designing the house so that few cut as possible are made on the plywood, it lessens the environmental burden, discarding few pieces.
» Decreasing header sizes from 2 by 10 to 2 by 4 and 2 by 6 and using a truss system and a double top plate to strengthen the walls, while still meeting building codes.
» Switching to ring shank nails for the sheathing and decking. Unlike a nail with a slick shaft, the ring shank nail has ridges up and down the nail that help to fortify the house. This nail has twice the holding power of a regular nail, HFHMCA said.
» Cladding the entire house in OSB (Oriented Strand Board) or plywood to make the structure sturdier and to provide a surface to nail without having to find a stud.
» Using 2 by 4 studs 24 inches OC (on center) instead of 16 inches OC.
» Wrapping the entire house with ½-inch polystyrene or blue board and taping the seams. A donation of materials from Dow Chemical facilitated the adopting of this practice. This provides an additional R-Value of 3, said Habitat.
» Utilizing a .44 vinyl siding and ventilated soffit, eliminating the cost and volunteer labor (usually 3 days) of exterior painting. A group of 12-15 volunteers can now hang the siding in less than a day, said HFHMCA. The siding is cut with either big shears or with a skill saw. The siding does not produce harmful dust and is a certified green rated product. Volunteers nail the siding into place with a roofing tack that is held in place by the blue board, making nailing significantly easier than with siding made from concrete based products. The homeowner still gets to choose the color of the siding and has 20 colors from which to choose.
» Insulating homes with R14-15 blown cellulose (“new wool”) that is insect, roach and fire resistant. This new cellulose also has been endorsed by the EPA as mold resistant, and creates a sound barrier, said Habitat.
» Grouping all of the products that use water in order to limit the run of pipes. Habitat’s goal is to keep the kitchen, bathroom and laundry room all within a 20-foot run of the tankless water heater, minimizing the wait time for hot water.
» Using programmable thermostats and educating homeowners about their use and the potential energy savings.
» Installing bamboo (3/8-inch nailed down bamboo floors with a 30-year warranty) or scored concrete flooring that is environmentally friendly and easy to maintain and using CFL light bulbs.
» Installing attic tents on pull down staircases reduce hot air pouring into the house in the summer and cold air in the winter.
» Achieving a HERS (Home Energy Rating System — the industry standard by which a home’s energy efficiency is measured) of 67 on an average slab or conventional foundation. The minimum score is 80. The new construction average – using older methods of building – is 100. HFHMCA said it is surpassing that by 33 points and exceeding the minimum rating for a 3.0 Energy Star certified house by 13 points.
» By using blue board and the R14-15 cellulose insulation, HFHMCA can boost the overall R- Value of a house to R17-18. (R-Value is a measure of insulation’s ability to resist heat traveling through it. The higher the R-Value the better the thermal performance of the insulation.) This could save a Habitat homeowner up to $35 a month on utility bills, making a difference on a tight budget.
Habitat staff members learned about some of these new principles that have been adopted during a HFHI conference in Florida. They adopted some of the principles referred to as “Miami/Dade County approved” that evolved from the construction challenges posed in Florida by hurricanes. The .44 vinyl siding and ventilated soffit are “green approved” and “Miami/Dade County approved.” They can sustain winds up to 200 miles an hour.
HFHMCA uses products that are easy to come by – that can be purchased at local lumber stores.
Other possible principles to include:
» Providing wireless alarm systems accessed through any device with Internet.
» Using HVAC systems that comply with Energy Star 3.0 standards.
» Installing 3-foot wide door openings and hallways and some ramps and zero curb entrances for easier access for individuals with disabilities.