Green product selection is a key component of sustainable design. Green products can be defined as those that reduce, recycle and renew: the 3 Rs of sustainability.
Choosing the correct wall system is part of good sustainable design. Today we are going to talk about steel frame wall systems, their benefits and drawbacks.
The steel framing members are galvanized C-sections with standard dimensions similar to wood framing studs. Steel framing can be a cost effective, sustainable alternative to wood framing.
Manufacture of steel framing members adheres to strict tolerances, which results in consistent strength, straightness, and dimensionally stable members. Steel framing provides excellent design flexibility due to the inherent strength of steel, which allows it to span longer than wood, and also resist wind and earthquake loads.
Steel-framed homes can be as energy efficient as wood-framed homes, provided that adequate insulation is used. It needs as much cavity insulation (providing the same R-value) as with wood framing.
Steel framing is more expensive then wood framing, about $1.00-2.50/sqft premium over wood framing, but an experienced builder can bring these costs down to a minimum. Panelized steel walls, built in a factory reduce labor and material costs, and other obstacles that are common in the field.
Benefits of Steel Framing- Steel is stronger than wood and more resistant to fire, earthquake and tornado damage, and can cost less to insure. Steel also does not rot, warp, crack, split or change with the weather and it is termite- and vermin-proof.
- contains a minimum of 25% recycled steel. 100% recyclability
- minimal job site waste due to standard quality (2% for steel vs. 20% for wood)
- life cycle energy savings due to the air tightness of the structure
- long structure life reducing the need for future building resources (zero depletion of iron resources).
- The use of steel-framed members enables builders and designers to earn credit points under Leadership in Energy and Environmental Design (LEED) Programs. The recycled content value of the steel produced exceeds the 5% and 10% goals in LEED.
- Steel framed members have consistent material quality. They are produced in strict tolerances in accordance with national standards
- Steel-framed structures are durable. Walls, floors and roofs consistently stay straight when built with steel framing. And, because the structure moves less than when wood framing is used, steel frames can reduce air leakage and energy costs.
- Steel framing is environmentally friendly. Steel is the most environmentally friendly choice, as it saves trees, is non-toxic and creates 100-percent recyclable waste.
- Steel framing members have pre-punched holes that allow for easy installation of electrical wiring and plumbing
- it's flexible
- light weight it is easy to handle, contributing to reduced labor costs and worker fatigue.
Despite these benefits, most contractors still frame only with lumber. Working with steel requires different tools and skills, so there is a big learning curve for carpenters, which can lead to higher labor costs.
Drawbacks of Steel Framing- Steel is more expensive than lumber (an average-sized, three-bedroom home would cost an extra $1.57 per square foot with steel) and mistakes are more costly.
- Steel can be difficult to work with in the sun and heat, and can cause lacerations if not handled properly. For this reason, some companies construct metal-framed walls in their shop to be delivered and erected on site.
- In certain locations, geographic or in the house (as in bathrooms and other wet areas), there is need for extra corrosion protection over and above the normal.
- Thermal expansion and contraction in some surfaces, especially sprung curved roofs causes loud movement noises. Similarly heavy rain noise can be intrusive.
- Aesthetics
- Thermal insulation. Steel is a good conductor of heat or cold, and as such extra measures have to be taken to insulate the residence. There are many cost effective methods of doing this.
Alternatives of Steel Framing: 1. Steel-Framed Modular HousingSteel-framed modules, (80-90% complete), are factory built and shipped to the site, where a crane drops them in place, and they are welded and bolted together. Although the materials are more expensive, they are very fast to set-up, saving on labor costs.
Alternatives of Steel Framing: 2. Light Gauge Steel Framing and Foam InsulationEPS core panels with steel framing elements, with R-values of R15-R23.
When properly constructed, steel framed walls are a good sustainable choice for building a house. Although slightly more expensive then a wood framed house, the small difference in cost is easily re-couped and surpassed by the long term benefits of steel frame homes, their energy cost savings, and reductions in home owners' insurance. Steel framed houses are high quality, sustainable homes.
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