Tag Archives: snow load

Winter Care and Maintenance

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These buildings are not industrial grade shelters and, as such, some caution must be exercised under some winter storm conditions….

Please see the WINTER CARE page in our installation guide for additional information. We also have a Winter Care FAQ page with articles we have posted on this topic

BEWARE of this sequence which creates a “worst case scenario”:

Freezing rain, followed by dropping temperatures, Lots of snow followed by rainfall. It is easy to triple the weight of the snow load in 30 minutes.

Our structures are designed in a gothic shape with a slippery cover to be lightweight and snow resistant. This encourages the snow to slide off quickly.
This is not an industrial high snow load building. We do our best to always point out applications where the capacity of the structure is being compromised. Extra hoops or thicker steel are an economical way to increase wind and snow load capacity. We take pride in the sturdy shelters we manufacture and supply, but must point out that we cannot warranty against weather conditions

Snow removal, when occasionally required, is a simple task. Uneven snow loading is deceiving, since the total weight is not a problem but the lateral force can cause the hoops to distort.It is rare to have any significant snow build up on the roofs; however,

DO NOT GO INSIDE A BUILDING WHERE THERE HAS BEEN OBVIOUS STRESS!
Be aware of these scenarios where excessive snow build up is possible and damage could follow:
A wet snowfall followed by dropping temperatures
A building 90° to the prevailing wind (drifts could form on the backside of the building)
A building attached to and situated downwind of a taller building (significant drifting)

A building 90° to another building that has a higher roof, could cause a surge in snow weight when the snow on the upper roof slides off.

Preventative measures for excessive snow build up (where possible):

Build structures inline with the prevailing wind
Build structures level from side to side to create uniform shedding
Do not attach your building to a larger existing building

Install a heat source to melt the snow

Economical additions to increase your structure’s snow resistance:

Install cable or tubular cross-ties at each pair of hoops, to create a triangle (when using cables there is no need to put them under tension)
Place wooden or metal support posts under the ridge. These can be suspended from the ridge with no more than ½” ground clearance. This will provide support as soon as there is load and structure movement will not dislodge your supports.

Use closer hoop spacing for the first 12’ section away from another bigger building

Pointers for removing snow:

NEVER remove all the snow from one side and then the other
Remove the snow off the top of your building before using a machine (snow blower, etc) along the sides

Use a padded piece of 1×4 wood on a pole (create a “T” shape) as the best tool for gently bumping the inside of the cover

BEWARE of this sequence which creates a “worst case scenario”:

Freezing rain, followed by dropping temperatures, Lots of snow followed by rainfall. It is easy to triple the weight of the snow load in 30 minutes.

Please call us if you have any questions about any of this. Thank you

Greenhouses 202: How to get your structure to survive the elements

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Norm will be speaking on Saturday morning at the Guelph Organic Conference at Guelph University. We are eagerly anticipating getting to see many of you either at the workshop or the trade show. Below is an overview of what Norm will be speaking about. Please contact us if you have any further questions.

The purpose of this workshop is to share some of my 40+ years of experience to save you some grief and expense. This workshop is an expansion of part of last year’s workshop “Greenhouses 101” which is on our website.

We will be covering the three forces which are exerted on a building: Up, Down and Lateral. These forces will be looked at in the context of aerodynamics and weather. Examples of each problem will be given and preventive measures to be used.

Some basic principles of engineering – how going wider and/or higher becomes exaggerated
Security of your building starts with proper anchoring. How much anchoring is enough or too much?
How is stability affected when the anchor point is not at the ground?
How does structure shedding rain affect the holding power of anchors?
How does recent excavation have on holding power?

Down force is commonly referred to as snow load. The most commonly asked question is “how is the structure rated for snow load?”

A worst case scenario is a combination of freezing rain, snow, rain and wind.
The issues with an uneven snow load – all on one side or all on one end
Issues of snow sliding from a higher building to a lower building
Shape and slope are important to good snow shedding.

How does a structure get evaluated for strength?
Going from wind load to snow load, shape and size do matter.
Proper ways to remove snow and or ice from a building.

Uplift and Lateral forces are not the same but very interrelated
Comparing the profile of a structure to an aircraft wing
What effects are there when the cover area is expanded by going higher or wider?
How does aerodynamics change for multiple units side by side?

What is the minimum space requirement between structures?
How does orientation affect the structure?
Forces on a structure with no cover
What constitutes a good wind break?

We hope you can come out and ask any questions you have face to face with Norm. It should be a great day!

Greenhouses 101: Climate and Air Effects on your Structure

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You might be wondering, How does air volume affect the climate in a greenhouse? There also is the matter of air changes. What is the connection between shape and aerodynamics? You need to make sure it stays put.

There are 3 forces on every building which need to be considered if you want it to stay where you put it and in the shape you built it. There is down force (usually from snow build up), up lift (by wind) and lateral shift (both wind and snow). Mother nature is not restricted by lack of patience and will work away at any vulnerabilities in the structure, often without notice until it’s too late. There must not be any wiggle room that the weather can work on these vulnerabilities or things will come loose, unstable, and wear out faster..

There simply is no such thing as too many anchors. There are also various tips we can give you for ensuring that the plastic is tight enough to avoid wrinkling and flapping about, while balancing the issues of it being too tight. This can easily extend the life of your roof cover.

We also advise, especially this time of year, to cover the structure as soon as you can as the more snow you have on that spot which has to melt, the more moisture you will have in the building. The more moisture you have in the building the more condensation issues you will have. You want to give that ground the most time possible to dry up before you need to start using the building.

Contact us for more tips and considerations for building a structure that will stay put and have a longer life, we would be happy to help you.

Check out the presentation video and the rest of the series Norm spoke on Greenhouses 101 here. Stay tuned for the end of  January 2016 when he presents Greenhouses 202!