|Conceptual Reference Database for Building Envelope Research||
Wood facts by CWC (Canadian Wood Council)CWC web: www.cwc.ca
In 1994, a devastating earthquake struck Kyobe, Japan. It rocked the earth beneath sheet metal structures, masonry block buildings and wood-frame homes. Modern wood frame homes - constructed using North American technology - outperformed all other building types. Yes, all other building types - even homes with sheet metal framing. Don't be surprised. The sheet metal used for residential framing is about the thickness of a metal soup can. Wood framing, on the other hand, is always a minimum of 11/2 inches thick. In addition, engineered wood products developed over the last few decades have produced roof trusses and floor joists with incredible strength over large spans. Builders using these wood products have much greater design flexibility than ever before.
These innovative wood products also benefit from one of wood's most unique and amazing qualities - resiliency.
This means wood will endure extraordinarily heavy loads, such as a sudden heavy snowfall, and retain its original shape.
The same cannot be said for sheet metal.
Peace and Quiet
Many residents of experimental sheet metal frame homes report that they find these homes noisy. Some report that plumbing noises are particularly bothersome, the floors squeak, and odd noises occur with temperature changes. The reason is that sheet metal reverberates sound. Wood brings peace and quiet, as it actually absorbs sound.
Greatest Insulation Value
Wood has the greatest thermal resistance or R-value of all common framing materials. Some builders are experimenting with sheet metal framing. Sheet metal conducts heat 400 times faster than wood. Localized cool spots at sheet metal stud locations can cause ghosting on interior wall surfaces. This is caused by indoor air impurities being attracted to these cool areas. Even with extra insulation, the overall insulating value of a sheet metal wall is up to 50% less than a wood-frame wall.
Incomparable Fire Safety
You'll be surprised to learn that in a fire, wood meets or exceeds the level of fire safety provided by a house framed with sheet metal.
Yes, it is true metal doesn't burn. Unfortunately, it melts. Tests conducted by the National Research Council in Ottawa discovered that in a fire a sheet metal framed wall can lose its drywall covering faster than a wood frame wall, due to the fact that as heat builds the attachment between the drywall and steel fails. (Remember, steel melts.) This loss of drywall is more than significant. Once a wall's protective covering is lost, flames and smoke move rapidly from room to room. This quickly decreases the time your family has to escape to safety.
Ease of Renovation and Home Improvements
Most homeowners know how to install blinds, hang pictures and create built-in shelving using traditional tools. Wood framing allows you to easily make these home improvements using the knowledge and tools you are familiar with.
Suppose that in ten years you want to add a room. Call a renovation contractor to confirm for yourself that wood frame construction is the easiest to modify.
You Know It Works
There are 20 million wood frame houses in North America. The oldest ones have been providing comfort and security for 200 years. Lifestyles, construction products and techniques have changed enormously. Wood products have improved and evolved to keep pace with consumer demands for high energy efficiency, increased strength and earthquake and hurricane resistance.
However, some builders will use experimental products in building homes. Will there be problems in the years to come? Will claims of performance be realized?
North American wood frame construction boasts 200 years of proven performance and is always improving. Can you afford anything less?
Over 80 per cent of Canadians believe that sustaining the environment is a major priority. Due to sustainable forestry practices, the volume of wood in Canada's productive forests increased by 3.8 per cent between 1981 and 1995. In 1998, over 700 million seedlings were planted. That's about 25 trees planted for each Canadian.
But how do we replace the thousands of tons of ore that went into sheet metal beams or aluminum siding, or the millions of litres of petroleum that went into making plastic components? The answer is - we can't. Those resources are finite. Once we consume them they are gone forever.
A study by the ATHENA Sustainable Materials Institute examined the relative environmental impacts of various building materials. The results clearly demonstrate that the manufacture of wood products is cleaner, less wasteful and consumes less energy than the alternatives. It is also a renewable resource.
Life cycle analysis shows that a sheet metal wall requires three to six times more energy to extract, manufacture and construct than a wood wall. The sheet metal wall also uses 25 times more water in its manufacture, and releases three to six times more carbon dioxide emissions.
The charts show the pollution created when manufacturing the building products necessary to frame a typical 2,400 sq/ft. single family Canadian home.
* Research used for charts was done by ATHENA Sustainable Materials Institute. For complete information, contact the Canadian Wood Council.