How do I make sure it stays where it is supposed to?

Pointers on anchoring, what kind of things will impact holding power of anchors,
anchoring after moving a structure

A phrase Norm has used thousands of times in his career is, “There is no such thing as too many anchors.” We consider it important to help customers understand the aerodynamics involved with a greenhouse shape.

The relatively small cost of the anchors is a short-lived savings after a building has blown away or shifted. By understanding and implementing what is required you can ensure a long term usage of your structure.

The job of your anchoring system is to counter the three aerodynamic forces working on your building.

  • Down force is usually seen as snow load
  • Up lift and lateral shift are forces typically associated with wind load
  • Wind going over a structure creates lift similar to wind going over an airplane wing

The first thing you will need to assess is what you are actually working with. If you have bedrock close to the surface, you have large rocks, or you have straight sand, it will impact your options for anchoring.

The actual holding power of your soil is an important consideration. Soil that has been recently excavated has considerably less holding power than soil that has not been moved in a long time.

The total surface area of an anchor post in contact with the soil is an important consideration. Large and short may have more contact area than long and slender.

When anchors can be used in alternating directions, it will multiply their individual holding power.

Wet soil usually does not have the same holding capacity as well drained soil. An important consideration here is rainwater which is shed by the building. As an example, with a 16’ wide structure, 8’ of rainwater goes each way. This means that the narrow area next to your building get 8 times the rain that the rest of the property gets. If you have poorly draining soil, this could be a potential problem.

If you are planning to use the movable structure option, proper anchoring has some additional challenges. Since your building is vulnerable to sudden increases in wind during this process, your anchoring protocol needs to be done quickly. Always do a test in the new area to confirm what you will be working with. With the quickness that is required, there is also a reminder that taking shortcuts will come back to haunt you.

We would like to reiterate, “If you are not 110% sure, please ask” There is no situation out there that is so unusual that we have not already been through it.

Your long term success is very important to us!

How Can I make my greenhouse its best?

Different tips to make it more efficient, proper space for plants, proper light,
when to heat and not

There are numerous ways of making your greenhouse more efficient and a better return for your investment.

The first question which needs to be answered, however is, “What does it need to be efficient for?” The answer to that should be in line with your goals and priorities for your greenhouse.

As an example, if you are not going to be growing in the winter, you will not need to make the structure “heat efficient” but you will need to ensure that it is “snow efficient”. If you are growing in the greenhouse through the summer time, the efficiency of your ventilation system is critical.

Making your structure more heat efficient (summer perspective) will be expanded on in post #5 and more heat efficient (winter perspective) will be expand on in post #6.

When you intend to start plants in early spring and then move the greenhouse to start another crop, the moving process can be made more efficient by installing “skis” under the base.

Anchoring concerns are touched on in post #3. This is also a way of making more efficient use of your property with investing in more greenhouse space.

When you implement a trellising program, you will make more efficient use of the floor space in your greenhouse. It is important to consider the need for your plant load being balanced on your structure.

Another important thing to be mindful of is the shading that is created when you implement vertical growing. Under certain conditions you may need to consider supplemental lighting to make things grow.

One consideration that is important to be mindful of as well, is that in the confined space of a greenhouse, you can not grow everything. This is not just a space limitation, but a climate limitation.

Certain plants prefer it warm and some like it cool. Other plants prefer wet and others dry. It will be more efficient use of your greenhouse if you collaborate with a like minded person. You grow more of certain things and the friend does likewise and then you trade the extras.

Here is to working together and growing together!

Air Circulation & Humidity Control

Even though many people would consider air circulation and humidity control as totally separate functions, they are closely intertwined.

You may have the proper sized openings to create the proper amount of air changes.

You could still have hot or cold spots in your greenhouse if you do not have proper circulation.

The same can be said about removing humidity.

For a ventilation system to have optimum efficiency and benefit, there must be balance. Having proper air circulation allows you to achieve that balance.

Horizontal air flow (HAF) fans typically come with a cage around the blades, a hanger bracket and a cord with plug. This allows them to be attached or suspended from the frame at the proper location. The motors are rarely more than 1/3 hp.

HAF fans always are installed in pairs and blow in opposite directions. A short greenhouse will have one in the front right corner and in the back left corner. A longer greenhouse will still have one in the front right and back left but also two half way down the length. The one on the right will blow in the same direction as the front right. The one on the left will be blowing in the same direction as the back left.

HAF fans should never be mounted in such a way that allows them to be blowing directly at plants. This would create an uneven drying. Some people will aim the fans slightly in the direction of the cover to ensure maximum air flow along the cover to maintain dry covers.

These fans run continuously to ensure that the temperature and humidity are spread evenly throughout. It also ensures that your thermostat or humidistat are reacting to air or moisture that is representative of what is going on in the greenhouse.

Ventilation is a difficult area of greenhouse production to get perfect. The more attention you pay to the details and modify what you are doing, the greater your production. The tricky part is that with all the variables, no two years will be the same. Carefully consider all your options and the situation you’re dealing with and you will have success!

The Variations of Passive Venting

In a nutshell, passive venting is creating an opening and letting the warm / hot air escape. The simplest form of this is opening a door or window. Just because it is simple does not mean that this method will be effective in cooling your greenhouse.

If your ends face into the prevailing winds, if you can make your doors big enough and if your greenhouse is short enough. That is a lot of “if’s” and you will still be doing a lot of running back and forth to have the correct amount of opening for the amount of ventilating you need to do.

We have already reviewed the most common form of passive ventilation in the roll up sides. It was noted that roll up sides work much better when paired with a high opening to create a chimney effect. It is a fact that hot air rises so the higher you can create an opening, the more effective it will be.

If you are relying solely on gable end windows, either motorized or manual, they will need to be quite large. You will also need to have the benefit of a regularly strong prevailing wind.

The most effective form of passive venting is a continuous roof vent. This will provide a continuous opening in the precise area where the air is the hottest. A roof vent should always be mounted down wind of the prevailing wind. The benefit of being down wind is that the wind creates a vacuum as it goes over the greenhouse and sucks the warm air out.  The air intake for a roof vent is often a roll up side.

A significant down side of a roof vent is the up-front cost. The cost is the same for a narrow and a wider structure. This is the reason they are almost exclusively put on wider buildings. The cost is simply spread out over a bigger area. The effectiveness of a roof vent still makes it appealing in spite of the cost.

Roof vents can be controlled manually with a chain fall opener or with a motorized gearbox. A motorized system can be a simple open / close controller that you set the limit switches or it can have a proportional controller that allows for pre-set stages. It is with an automatic controller that the benefit of the roof vent will really become apparent. Every couple of minutes it will react and adjust to the inside condition of the greenhouse.

All of the expenditures involved with your greenhouse need to be weighed as a cost versus benefit or cost versus return. This process is especially challenging when considering the options of ventilation. Many of the expenses are subtle and hard to measure. The returns are equally hard to quantify since weather is an additional variable. This makes it even more important to keep accurate records and be aware of your options for improvements.

Long Weekend Hours

Multi Shelter Solutions will be open on Canada Day and closed July 2nd. We will reopen 9am July 5th. Have a safe and happy holiday weekend!

Installing Wire Insert on Multiple Layers of Plastic

In response to a few questions about increased difficulty of installing the wire insert on 3 layers of 7.2 mil plastic. I have done my experiment with zero added degree of difficulty.

I don’t want to leave it just like that. I would like to add a few points.

First of all, the temperature was about 18C when I did this. It will progressively get more difficult because the plastic is less pliable as the temperature gets colder.

I should follow this up with the same experiment when the temperature is below freezing.

For my experiment I put extra screws into the channel simply to increase the chances of interference between wire insert and screws.

I had one instance where it was a little more tricky and had to push a little harder.

I could see that there could be a possibility where you might need to take out the wire insert and start 1 centimeter over.

There are a few things which I wish to point out on logistics and technique. There is a critical thing to remember for the helper who is pulling on the loose plastic.

He/she must be pulling at least 30 cm ahead of where the wire is going into the channel to allow the necessary slack to get the wire into the channel.

The same applies for the person inside the structure who is pulling on the end wall cover.

Inserting the wire insert is very much a wrist action and proper technique is probably even more important when doing 3 layers of 7.2 mil

Your thumb should be on the next equal bump (either up or down) so that you can apply some twisting action to the insert.

Never simply slide the insert up and down as this can abraid the cover.

I hope this helps

Norm