Lake Tahoe Basin Inundated With Snow

With the massive amounts of snow the Lake Tahoe Basin has experienced over the last few weeks, there is one question we continue to be asked: When should I shovel my roof?  Zachary Engineering's SnoLoad Calculator provides a quantatative approach to estimate when its a good time to get the snow off of it!


But before we walk you through the simple process, check out some images from the most recent storms!









As you can clearly see, so much snow in a short period of time! 


Step 1


Go to the SnoLoad Calculator.


Step 2 


Enter your full address, including state and zip code. Click Calculate. The map should zoom into the provided address, and an information box will appear.


Step 3


Check the Maximum Anticipated Snow Depth. This is the last line in the information box. If a Maximum Depth does not appear, see below.


Note: There are some locations that SnoLoad Calculator will not produce a Maximum anticipated depth. If your address is one of these, there is an easy way to figure it out. First find the Ground Snow Load. We are going to make an assumption for the Snow Density at 25 pcf (pounds per cubic foot). Next, take the ground snow load and divide it by 25 pcf. This will give you an estiamte of the Max Anticipated Snow Depth.


Step 4


Estimate the Max Depth for the roof. At this early stage in the season especially, it is better to be conservative. Therefore, we recommend that when the snow depth on the roof reaches 50% of the Maximum Anticipated Snow Depth at ground level, it should be shoveled. For example, if the Maximum Anticipated Snow Depth at ground level is 9.0 ft, then 4.5 ft of snow on the roof would warrant clearing to prepare for the next storm. In addition, common sense should be used. If your roof is approaching that Max Depth number, and there is a large storm on the horizon, then keep in mind that it will likley not be possible to clear during the storm. It might be prudent to have the roof cleared prior to the storm.


Step 5


Be safe! While it is possible to clear your roof on your own, this can be dangerous. As such, we recommend seeking the services of an experienced professional. Please keep in mind that each side of the roof should be cleared at the same time whenever possible, meaning that one side of the roof should not be completely cleared until the opposite side of the ridge is also cleared. We recommend clearing in stages. This will help avoid unbalanced snow loads on the roof. There are lots of stories out there about roofs that fail during or immediately after clearing, and the primary reason for this is inadvertently creating unbalanced snow loads for which a roof might not have been designed.


We hope this helps you in your determination! Please feel free to send us pictures of the large amounts of snow on your roofs, and they might end up on one of our slideshows!


Note: This approach should be taken as an estimation only, and does not replace the advice of your design engineer. Zachary Engineering cannot guarantee how your individual roof was designed or built, and as such cannot state without a doubt if your roof will fail under certain conditions. The SnoLoad Caluclator does not calculate Drift, Impact, or Ice Dams loads. Seek the advice of your design engineer if your roof is experiencing excessive deformation or if you are noticing any kind of interior damage due to large amounts of snow.


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