I have to think that most home owners haven’t put a lot thought into how their roof is designed. The structural integrity of your roof is engineered right down to how many pounds per square foot it can sustain. We call this the snow load. Your roof and its snow load will differ depending on where you live.
Local building codes dictate the amount weight a roof must hold up. The code in Atlanta Georgia will be different from that of Chicago Illinois.
As of this writing there is about 15” of snow on my roof, I live just outside of Grand Rapids, Michigan. At the same time there is over 24” on the roofs in Holland Michigan, due to lake effect snow. But not to worry, these roofs have been designed to withstand this much snow. Tomorrow’s forecast is rain and the snow will absorb this rain which will increase the weight on your roof. Yet once again your roof has been designed to handle this. Using a roof rake, which is a blade perpendicular to a long pole, to remove the snow from your roof is always a good idea. They can be purchased at most hardware or big box stores. I used one today to remove the snow from the eves of my house.
One problem with snow on your roof is when it causes ice dams at the eves. If your roof is not properly insulted and vented, ice dams will build up on the edges. No matter how much insulation you have there is going to be certain amount of heat that is going to escape and this is where proper venting comes into play. You want this heat to escape out though the roof vents. If it does not, it warms your roof, the snow melts and the water runs down to the eves where it freezes, causing ice dams. As this continues eventually the water will back up and your roof will begin to leak.
If you live in an older home that can’t be properly vented more insulation may not help. You can install a type of hot wire along the edges of your roof that heats up just enough to melt the snow. This will prevent ice dams from occurring. If you have large icicles hanging off of your roof, you should try to remove some of the snow and you may want to contact an insulation contractor to take a look at your home. As always think safety when working on your home. Never use a roof rake near the electrical wires leading into your house and be careful when using ladders.