Helpful roofing information
The deep snows and extreme temperatures of the Sierra Nevada winters place great demands on the exterior of mountain homes. These demands are nowhere greater than on the roof system. Answering these challenges through the correct use of the best modern building materials in concert with the finest workmanship is our mission.
The Roofing Equation
The Roof Snow pack
On Tahoe homes, controlling (and/or cooperating with) the snow pack and its motion directs us toward correct roofing solutions. Too much snow on a structure can cause the collapse of the structure. However, more damage is done by sliding snow than structural failure from the weight of snow. Sliding snow can damage the roof and its components: plumbing vents, heating vents, chimney chases, skylights, etc. Sliding snow can also wreak havoc on whatever it hits on the ground: decks, rails, walkways, vehicles, even occasionally causing personal injury or death.
Whether or not the snow will slide from the roof is dependent on a variety of factors including: roof slope, valleys, dormers, layers in the snow pack, temperature changes, etc.
One technique used in controlling the snow pack is the use of different roofing materials. The two dominant roofing materials used in the Tahoe area are metal panels and composition shingles. The high friction surface of composition shingles will help prevent snow from sliding. The low friction surface of metal roofing will facilitate sliding. Analysis of individual homes is needed to determine which approach is appropriate. Our experience can help with these decisions.
The Ice Dam
Ice dams are caused when the heat from the interior of homes (or solar heating) causes melting in the roof snow pack. The resulting free water runs down the roof surface until it encounters the unheated eave overhangs of the home. Here, the water freezes if the exterior temperature is less than 32 degrees. The ice can now grow in layers, reaching depths of two (2) feet or more. This "ice dam" holds liquid water behind it (all this goes on under the snow visible on the roof). The liquid water behind the ice dam can back up under shingles and roofing underlayments, causing interior leaks.
The solution to the ice dam problem lies primarily in the use of self-sealing ice dam protection membranes. We use only W.R. Grace Vycor Ice and Water Shield membrane. Our standard details include installation of the Ice and Water Shield on the eaves to meet or exceed county codes and one three (3) foot wide course in all valleys, and on all roof to wall intersections.
Another solution to the problem is using Ice melting systems at eaves. This is a very effective way of not allowing ice dams to occur. If you are interested in such an application please request an estimate.
When the warm moist air of our living areas caused by breathing, cooking, bathing, etc. comes in contact with the roof decking, water condenses. If this condensation cannot be carried away by venting (such as an attic), the water will collect in the adjacent wood of the structure and/or in the insulation. This can create major structural problems and/or decrease insulation effectiveness. This occurs with both metal and composition roofs. Furthermore, all composition shingle manufacturers require ventilation of the roof deck for the proper function of their shingles. If the roof deck is not vented, shingle warranties may be void.