Tag Archives: wind and greenhouses

Wind braces for structures

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There is no dispute on the need for wind braces on any structure. There is often confusion on how and when those braces need to be installed.

The sooner that some sort of bracing is installed on a building, the easier it is to maintain plumb or vertical. For this reason, we stress the importance of tying off a building, both ways, as soon as the first section has been erected.

One detail that many overlooks are the total surface area of the hoops. It does not take very long to have the combined surface of a 4’x8’ sheet of plywood. For this reason, it is important to not rely for an extended period on your initial tie-down ropes as your “bracing”. There have been instances where the combined surface area of the hoops is more than the entire gable end.

If you are doing a long building with long hoops, i.e. 30’ wide, it would be wise to install the bracing before the whole structure is assembled.

Wind bracing can be installed in two directions, one goes away from the end wall and one goes toward the end wall. Both ways are acceptable, provided that you do both. If you install them toward the end at one end, you must do the same at the other end. By doing the same concept at each end, you are essentially holding things in opposite directions.

When bracing goes away from the end, the load is referred to as “tensile load”. Cable is often used for this. The cable and the clamps used must be rated against stretching and breaking. This is a convenient system since you are not limited by a precise measurement. When using this system, it is important to end up at the ground, in the 4 corners.

When bracing goes toward the end, the load is referred to as “compression load”. Round tubing with flattened ends is most often used. It is important to make sure that the tubing is strong enough as to not bend as it is being compressed. This is the method which has been used the longest since the instinctive way to brace something it to “prop something against it”.

With either method of bracing, where you start and end is very important. For bracing to be effective, you must start at a point that is connected to the whole structure. This would be either the ridge or a row of purlins. Starting at a mid point of a hoop will give little reinforcement since the hoop can flex from side to side. The closer that bracing goes at 45 degree angle, the stronger it will be.

In the case of longer hoops with multiple rows of purlins, it is advisable to have a series of shorter braces than one long one. This means you would start at a certain hoop/purlin connection and go down and over for 3 or 4 hoops and anchor at that hoop/purlin connection. Go over to the same hoop you did the first brace on and repeat the process from the lower purlin. You would then be going down to the base or the next row of purlins. Remember that if at one end, if you are going left to right, on the other end you go right to left.

Where ever you end up, it is wise to have extra anchoring at that point.

For extra clarification, please watch our “installing wind braces” video on the website.

How to Manage Structures in Extremely Windy Locations

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Click to watch the video

How to Manage Structures in Extremely Windy Locations

One of the things which frequently comes up in the conversation with new customers is that they are in a very windy location. This is important to take into consideration when making suggestions for a building.

Occasionally we are faced with an intensely windy location. The question becomes, “Can I build a greenhouse in such a spot?” The short answer is “yes”. There are five potential suggestions which we make to improve the building so it is better able to withstand regularly brutal winds.

-Go with a lower profile shape since it catches less wind. Normally we recommend high profile since it sheds snow better but in super windy locations, snow is not an issue.

-Go with narrower hoop spacing. Going from 4’ to 3’ spacing increases the strength by 33%. Sometimes it is even worth going to 2’ spacing.

-Put in more anchors. There simply is no such thing as too many anchors! In super windy locations it is worth doubling up on the anchors. It is also important to double up on the fastener between the base beam and the anchor.

-Install cross ties. Cross ties tie the left and right sides of the building together. This means that when there is added pressure on one side, the other side is assisting by holding things back.

-Go with a double plastic cover with air between. It is amazing how the cushion of air acts like a shock absorber and stiffens the building.

Depending on the severity of your situation, adding a few of these to your building may help achieve the peace of mind you are looking for. We have had situations where a customer has added all five suggestions and been extremely grateful for the rigidity which has been gained.

As much as you, we want this building to serve your needs for many years with peace of mind.

What is the best size and shape for what I want to do?

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Covering the sizes we are offering and when it would be best to choose from the website for a more custom situation.

Determining the space that is required to meet your objectives will be your first consideration. This goes beyond the foot print or floor space which you would need for the plants you wish to grow.

In our Self Sufficiency packages, we are offering the convenience of 3 choices. There may be a situation where none of these choices will meet your short term objectives or long term goals. If that is the case, it would be advisable to explore our website for a more suitable package in the context of what you are learning here. The self sufficiency packages are meant as a simple starting point, but sometimes simple isn’t always the best choice

If it is your goal ultimately to have more than one greenhouse, consideration needs to be given for how the second or third building would fit on your property. As an example, if you have a total of 50’ wide available and you build 16’ now, it restricts your future options. Going a little longer now (if that fills the space) is much cheaper and simpler than doing an addition.

If it is not your intent to grow (and heat) through the winter time, it would be important to have a structure which would efficiently shed snow. Using a more snow efficient shape does not mean that the structure can be left totally unattended for extended periods of time. If that is going to be your situation, we have options for building structures to meet that requirement with closer arch spacing.

A very important reason for needing a taller building would be the need to use the vertical growing option. You will be able to grow more rows on that foot print because of the side clearance provided. If you plan to only grow short crops in the soil a lower greenhouse will work.

A point that many overlook in their consideration of the importance of side height is that they intend to work the ground with a rototiller.

A final point for the shape consideration, has to do with wind load. Wind load increases exponentially as the building is taller. Especially if your property dictates orienting the building across an extreme prevailing wind, it would be advisable to go with a lower profile.

Here is to comprehensive planning!

We hope you are finding value in this series of posts, helping you prepare for your new growing adventure! Reminder that the deadline is May 31st for Fall Delivery. We look forward to working with you for your projects!

Where is the best place to put the greenhouse?

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Considerations for determining optimum location for growing,
air flow, snow shedding and ground moisture

The first bit of advice we share when asked that question is “Do not put a greenhouse in a place that is not good for anything else”.

You need to pick the best spot to accomplish the goals for your greenhouse. Any of the reasons why this spot would be less than desirable, will come back to haunt you.

This is particularly true when it comes to ground water. If a particular piece of land is always moist or has a very high water table, moisture will be an ongoing problem. A greenhouse will trap and exaggerate excess moisture and become a very unhealthy spot for plants.

If the soil is sub-standard or undesirable where you put the greenhouse, you will be putting extra effort into bringing the soil up to standard.

Proper consideration needs to given to shading on the property. Plants grow in direct proportion to the amount of daily light they receive. Really analyze where and when shade happens. Vegetables and flowers need sun.

A greenhouse needs to be level from side to side so shed snow uniformly. With uneven snow load on a building, it will surprise you how little snow can be a problem. 

Excavation to level a site is usually expensive and messes with the make up of the soil. There are ways to build up the low side if that becomes necessary for the location of your choice.  Some end to end slope is not a problem structurally.

It is generally acknowledged that a north/south orientation will pick up the sunlight better but this is not a serious consideration unless you are into production crops.

If your prevailing winds are constantly hitting the side of the structure, there will be a sideways push which is good to avoid. This orientation will also encourage uneven snow loading. Ventilation is typically easier if the prevailing wind hits the end of the building.

Since the chances of having the “perfect” location, is not likely, it is important to evaluate all of the angles.  Some of the undesirable points can be worked around better than others.

By doing a thorough assessment and then prioritizing, you will be able to come up with the closest to perfect that is practical. You will also have an idea beforehand on what needs to be done sooner than later.

Here is to happy planning and planting.

We hope you find value in this series of posts, helping you prepare for your new growing adventure! Reminder that the deadline is May 31st for Fall Delivery. We look forward to working with you for your projects!

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!

You’re in a Windy Area? We can help

Posted on by

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!