They do not. You will hear on the radio gutter companies stating that their gutter cover/helmet system prevents ice dams. Gutters have nothing to do with ice dams. Ice forms when the snow at the warm peak of the roof melts and refreezes on the cold edge of the roof. The gutter is designed to carry roof water away. In cold temperatures, it will freeze that water. However, the ice was already freezing on the edge of the roof anyway. The ice dam has formed along the edge of the roof because of 1 or more of 4 reasons; lack of insulation, poor ventilation, gaps not sealed, and/or roof design. Click here to learn how to prevent ice dams.
If you swing a hammer or a hatchet a thousand times, every now and then you are going to swing too deep and damage the shingle or gutter. Steam is the only effective way to safely remove ice from a roof. Never use a hammer, hatchet, ice pick, chain saw or anything other than steam to remove an ice dam.
Water that is pooled behind an ice dam will drain away when a channel is cut into the ice dam. However, that is for immediate relief only. Channels will quickly fill and refreeze resulting in pooling and water again leaking into the home. The only way to prevent that from reoccurring is to completely remove the ice dam.
A gun that does not have a trigger is dangerous to the operator and to the home being worked on. A gun that is dropped and where there isn’t a trigger release to shut off the flow of steam can injure the operator and can come in contact with the home causing damage to paint, siding, etc. Also, when an operator is removing ice, he needs his hands to remove ice and to reposition the tool to efficiently melt the ice. Without a trigger, the steam continues to stream which results in more excess water being used. A trigger on steam machine is a vital safety component.
Roofs are not designed to be waterproof. They are designed to shed the water off the roof. Roofs are made up of plywood decking, tar paper, ice shield along the bottom 3 feet of the roof and shingles. The tar paper is what is primarily designed to keep the water out of your home. The shingles are designed to protect the tar paper. The plywood needs to be able to breath in order not to rot. None of these items are waterproof. The problem comes when water is not allowed to exit the roof, the ice dam. Ice dams must be prevented or removed in order for a roof to perform properly.