Tag Archives: wind requirements

You’re in a Windy Area? We can help

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We have many structures in very windy locations from coast to coast. This is probably the most common comment we get from people who reach out to us. We have experience and extra steps we take to help ensure your structure doesn’t end up as an expensive kite. We have been diligent in our articles and instruction manual to help these situations, but ultimately it’s up to the customer to heed these warnings.

One of the things that is stressed in our assembly instructions is the importance of tying your frame off in both directions as soon as you have the first section of ridge installed. This is typically done with rope coming down from the ridge as an inverted “V”. The sooner this is done, the easier it is to hold everything plumb.

It is worth noting / stressing, that this is not a long term replacement for the wind braces. The wind on the collective surface of all the hoops is capable of exerting a tremendous amount of force.

When one does the math, there are actually cases where the wind pushes with more force when there is no cover on the building then with a cover!

A 20’ x 48’ x 12’ high structure with 4’ spacing has the same amount of hoop surface as an 8’ x 14’ wall. This is an example why the ropes used to hold the frame straight is not intended as a wind brace.

Once the hoops are all installed and the purlins attached, it is important to install the wind braces before proceeding. The purlins are what tie all of the hoops together and then by angling the wind braces down from the rows of purlins, you would be bracing the whole structure.

In photos on our website,you will see our smaller structures have fewer wind braces than the larger ones, which accounts for the above math mentioned. This has been developed with our experience, as well as the engineers who have assessed our structures.

There are different notes on placement, direction and location that will help your structure survive the wind as well. We do our best to go over all the scenarios with you when you’re discussing your purchase with us. The more details you can give us the better. Obviously we aren’t able to account for everything you may encounter, but it is our intention and mission to set you up for success as best as possible. We don’t want your greenhouse to end up flat or blown away anymore than you do! And this is also why we reiterate,

There’s no such thing as too many anchors!

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 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!