By STEVEN SATURNO, P.E. | Special to Moonshine Ink
The last eight weeks have brought us historic snowfall, and the anxiety of wondering if your house and body can endure any more before both start to fail. As I write this, atmospheric river number nine of the season is bringing yet another round of heavy rain and snow to the area. Since I am a local home inspector and licensed engineer, several of my friends, neighbors, and clients have asked me questions such as: How much snow can my roof handle? Is my deck going to fall? Why are the drywall cracks in my house opening? Is that new “water feature” dripping from my ceiling going to be a problem?
Snow Design Facts
On Jan. 26, the Town of Truckee put out a press release encouraging residents to clear roofs of snow and ice prior to the next storm. That notice put a lot of fear in some people, and a sense that their roof might collapse if another foot piled up. Snow load design for the Town of Truckee and Lake Tahoe is determined by location and elevation. Generally, homes close to lake level are designed to handle about 6 or 7 feet of snow on the roof, assuming 25 pounds of weight per cubic foot. Add some rain, ice damming, and heavy “sierra cement,” and that snow density is easy to reach or exceed. To put it in perspective, ice weighs about 57 pounds per cubic foot. Keep in mind that uncovered decks are designed to handle much more than this roof snow load.
Drywall is a brittle material. It cracks instead of bending. When snow accumulates on your roof, and the wood framing starts deflecting, it’s pretty common to see drywall cracks. Don’t be surprised to see cracking above doors, windows, and wall openings where your roof is bearing weight. The drywall is nailed to structural header beams over these wall openings and will crack long before the wood breaks. If the drywall cracks are big enough to stick a finger in, it’s time to call your contractor.
Roof Ice Dams
Ice dams occur when heat loss from your house melts the snow on the roof, then refreezes over the unheated roof eaves. Ice builds up on the eaves and traps snow from shedding freely off the roof. In bigger snow years, ice dams can be the reason for an unprecedented amount of snow remaining on the roof, and can lead to structural or roof damage. Heat tape may be the answer, but there are a few things to keep in mind if you’re pondering installation: It may only be needed on certain areas of the roof, not necessarily at every eave. Consider installing timers instead of basic on/off switches so that your electric bill doesn’t get out of hand.
Water Entering Your Home
Water leaking into the inside of your home during a storm can be more frustrating than sitting in Squaw traffic on a powder day. Whether it’s water entering your garage from a down-sloping driveway, percolating up from a concrete floor slab, or leaks in your roof, the solution is often expensive. Your best line of defense at the ground level is making sure any water is diverted around your house, instead of toward its footprint. If you find excessive water in your crawlspace, you may need to install waterproofing and/or a drainage system on the exterior of the foundation walls. One drainage option is a French drain, a trench filled with gravel or rock or containing a pipe to redirect water to the low point on your lot.
I have also witnessed many steep driveways with water cascading into garages. Trench drains or channel drains are good secondary systems to solve these problems, but a well graded driveway should be your first defense, including a well-defined dip before the entrance to the garage that slopes to one end, and ideally drains to the low point of your property.
A friend of mine woke one rainy morning in January to find his sunken living room had turned into a wading pool. Luckily, he has a sump pump installed, which can move water out of unwanted places. Unluckily, with rising groundwater and power outages, his pump was sitting idly in the dark. Consider a battery-backup sump pump and a warning system that either makes noise or notifies your smartphone.
Waking up to find a puddle collecting in your living room might be your worst nightmare. There isn’t a lot you can do until the storms cease, and the snow on your roof melts. The most common failures I see happen in roof valleys, where snow collects and melting snow drains. Often, it is the fault of poorly installed metal flashing, designed to bridge the gap between two adjacent roof surfaces. Time to call a licensed roofing contractor. But until they are able to do any repairs, don’t be afraid to open drywall to let the water drip freely. The last thing you want is a roof repair and an extensive mold issue. Drywall, after all, is easy to repair. Mold, not so much.
~ Stephen Saturno is a Certified Professional Inspector, licensed civil engineer, and owner of Saturno Home Inspection. He does residential and commercial inspections in the Tahoe/Truckee area. Despite his extensive knowledge of snow and residential design, he still bought a house that sheds snow on his driveway and decks.