The number of stages refers to how the snowthrower moves the snow. A single stage snowthrower uses the front auger to sweep and throw the snow in a single action. Single stage machines are designed for lighter-duty applications, such as small driveways, steps and short sidewalks. They are generally lightweight, maneuverable and easy to use -- ideal for areas where snowfall is relatively light to medium throughout the winter. Dual stage snowthrowers use the front auger to sweep the snow and feed it to the impeller. The impeller then propels the snow up and out the chute. The auger turns slowly to control the amount of snow the impeller throws. Dual stage snowthrowers are designed for heavier applications, such as larger driveways or long sidewalks -- great for areas where conditions range form moderate to extremely heavy, wet snow.
Sometimes referred to as I-beams, are structural, load-carrying products. I-joists are typically available in long lengths and because they are very lightweight can be easily handled at the jobsite without the need for costly handling equipment. Their “I” configuration provides high bending strength and stiffness characteristics. The top and bottom flange material for I-joists is typically dimension lumber or laminated veneer lumber; the web material is OSB or plywood. Prefabricated wood I-joists are used extensively in residential construction for both floor and roof framing and are among the fastest growing of the glued engineered wood products.