Greenhouse Covering with 120 LBS per square foot of snow. That equates to 15 feet of snow! 

Solawrap greenhouse plastic is a clear plastic film that has a track record for withstanding heavy snow loads**- 120 LBS per square foot of snow. That equates to 15 feet of snow! 

Aren't all greenhouse structures essentially the same?

NO! The difference is in the steel and in the greenhouse plastic covering! Below is regular greenhouse covered in SolaWrap in Ishpeming, Michigan.  Snowfall is 161 inches. The average US city gets 26 inches of snow per year. The number of days with any measurable precipitation is 83. On average, there are 184 sunny days per year in Ishpeming, Michigan. 

** How much does snow weigh (Snow load)?

Structural engineers use building codes to determine snow loads on greenhouse structures that are custom designed for the exact location where they will be erected.  Currently, the International Building Code or IBC is used in the United States for snow loads. It is up to the sates and/or local jurisdictions to amend or supplement the IBC, or adopt their own code.

The building code identifies the ground snow load, which building designers use as the starting point to calculate the uniform design snow load on a building roof.

What is Ground Snow vs Roof Snow?

According to the International Building Code, 2012:

"Ground snow load is defined as the weight of snow on the ground surface. Ground snow load values are established using data collected by the National Weather Service. Maps of ground snow loads in IBC and in ASCE 7 indicate a 2 percent probability of the indicated load being equaled or exceeded in any given year. Ground snow loads do not discount that actual snow loads may exceed them, only that the risk of snow-load-induced failure is reduced to an acceptably low level."

Roof snow load is defined as the weight of snow on the roof surface used in design of the building structure (IBC, 2012). It is determined based on multiple factors, including:

• Ground snow load value
• Importance, occupancy, and use of the building
• Wind exposure of roof
• Roof slope
• Roof shape
• Roof obstructions
• Thermal condition of the building

Snow Type affects Snow Load

It comes as no surprise that snow comes in many forms in many different parts of the country. Altitude, humidity and season can affect the density of the snow.  The weight of 1 foot of fresh snow ranges from 3 pounds per square foot for light dry snow to 21 pounds per square foot for wet, heavy snow (Gooch, 1999)

When it comes to snow load, what weighs more Ice or Snow?

 Ice does.  One inch of ice weighs a little less than 5 pounds per square foot, and 1 foot of ice weighs approximately 57 pounds per square foot. Ice weighs significantly more than heavy, wet snow per inch depth. In part, this is why it is important to prevent ice buildup on a roof structure.

 There are so many factors to take into consideration when you are planning for a greenhouse. Give us a call and let us help.