While snow can pile up on any rooftop, greenhouse owners have to worry about roof damage long before the average home or business owner. A sudden, heavy snow could also lead to a greenhouse collapse. Hortica has some tips to help you protect your buildings all winter long.
Reduce the risk
Each snowfall is different. Some snow is light and fluffy, with 12 inches having the same amount of water as one inch of rain. Or, it can be wet and heavy, with 3–4 inches equaling an inch of rain. It’s important to remember that one inch of rainwater weighs 5.2 pounds per square foot. That adds up to about 6.5 tons on a 25–by–96–foot greenhouse roof.
The best place to begin your safety preparations is inside:
- Keep your system up to date: Check and maintain your heating system.
- Check system functions: Make sure your environmental control system and temperature alarms are working properly.
- Get an early start: Give the heating system time to warm the cladding, so that once the snow starts, melting will too. Here are some things to keep in mind:
- Remember that starting the heat once a snow load is on the structure can sometimes do more harm than good by causing unbalanced loads.
- Be aware of any heating requirements in your insurance policy. Know that temperatures higher than what your policy requires might be necessary to achieve a good melt.
- Heat smart: Consider taking these steps for best effect:
- Open your shade/energy curtains to allow the heat to get to the covering and/or gutter.
- Deflate poly on structures clad with double poly to allow the heat to transfer between the bottom and top layers.
- Be aware of any pocketing of snow and water.
- Alleviate loading: Determine if it’s safe to do so, then push the snow/water out of pockets to lighten the load.
- Check for outdoor risks: Identify structures on your property that are susceptible to snow collapse (low profile, snow traps, etc.) and create a plan to keep the snow off these areas.
Prepare for snow removal
If you plan to remove snow from your greenhouses, know where you will put it. Avoid piling it in areas that could obstruct a curb or a hydrant that a plow might hit. You should also prepare before the snow flies by maintaining proper snow removal equipment and putting it in an accessible place. Here are some other helpful items to have on hand:
- Lumber: Make sure the boards are the right length to brace structures and complete temporary repairs.
- Extra poly: Have this on hand for a temporary repair to help you maintain heat in damaged structures, possibly saving your crop and other buildings.
- Torpedo heaters: Use these for extra heat, but be mindful of clearance/fire hazards and the effects of the exhaust on your crop.
- Brooms: Push snow off your poly structures without damaging the cladding.
Before you build
f you plan to build any new greenhouses, you’ll want to consider the kind of snow load your area is likely to receive. And if a new structure is being built next to an existing one, consider:
- Whether you’ll unintentionally create a snow trap
- If the spacing between the structures allows for equipment to pass through the alley
- Whether any addition to an existing building will impact the engineered design
By taking early precautions, you’ll help keep your operation running smoothly and efficiently throughout winter.
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