Frequently Asked Questions

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The following list are the questions we are asked the most. Of course if you dont find your answer here, please feel free to reach out to us with any questtion you might have!

How do I determine a size? Should I go longer or wider?

First you must consider where you are placing the greenhouse, how much room do you have? Next thing to consider, it is typically more cost effective to go longer than wider. The wider a greenhouse goes, sometimes material has to be thicker or more robust to accommodate snow/wind loads. Or, support post may have to be added. You will want to think about how you want to use the greenhouse to help determine layout, which will help you determine your ideal size for your space. Raised beds range 4’-6’ feet wide (depending on arm reach length), aisle ways are normally recommended to be at least 3’ wide and plant benches are usually 3’ wide. These are all things to consider when determining size.

Where should I place my greenhouse?

A greenhouse’s placement should be determined by sun exposure. You will want to research how much sunlight your plants will require to grow and bloom.  A greenhouse can either be a freestanding unit or attached to your home. An attached greenhouse is more convenient, as you can avoid inclement weather when necessary. Attached greenhouses may also be less expensive to build and provide easier access to utilities such as water, electricity, and any required heating/cooling source. However, attached units may require a building permit. Detached greenhouses allow for more flexibility with regard to size, shape, and exposure to the sun

Do I need electricity, or a water line in my greenhouse? Any other utilities? Do you install those?

Most structures require some form of heating and cooling system if you want to use it all year, so you will want to determine if they are gas or electric powered. If you plan to include lighting or outlets, electricity will definitely need to be incorporated.  You should also consider how the plants will be watered inside the structure (a hose or irrigation system both require a water line).

We do not install any of the utilities in your greenhouse. We also do not make any utility connections to equipment in your greenhouse as we are not trained or licensed to do so. We can however work with your local contractors and answer any questions they have to help get everything set up correctly.

How do ridge vents and side vents work, are they affective?

Remember that your greenhouse will typically be at least 10-20°F warmer than the outside temperature. Especially in hotter climates and in summer months. Ridge vents work by using a combination of wind and thermal action. The wind creates a vacuum effect that pulls the hot air out of the greenhouse. The sun starts thermal action, which heats the roof and causes the hot air to rise. The ridge vents also allow the air to circulate. If there is a breeze outside, it will enter the greenhouse and help circulate the air; this reduces the spread of disease. Air circulation is also essential to photosynthesis: all plants need carbon dioxide to stay alive. Without good airflow, plants won’t do as well when it comes to capturing CO2 and staying healthy. Adding side vents allows for more cooling and air movement as well. It creates a convection current. Wind plays the major role. Wind passing over the roof creates a vacuum and sucks the heated air out the vent. If sidewall vents are open, cool replacement air enters and drops to the floor level. If the sidewall vents are closed, cool air enters the bottom of the roof vent and the heated air escapes out the top of the vent.

What type of foundation do I need?

The foundation is the whole system on which the greenhouse is set upon. There are different options to choose from. Whatever type you’re going with, they all have one thing in common, though: it needs to be square, level and plumb! First, check with your city’s building department and HOA if you need a permit for your project. There are also zoning requirements that have limited or specific types of foundations and other codes.

Below is a brief description of some common foundations: 

Bare Dirt:

A compact bare dirt foundation is NOT an option for your greenhouse. The weight of the greenhouse and the freeze/thaw cycle of some locations may cause ground heaving and frame warping. This can cause glass breakage and frame leaks. 


As with above bare dirt foundation, this one is not our top recommendations. With some modifications and a little extra work, this option may work though. A deck doesn’t provide much insulation from below, so you will want to add insulation or not plan on using it in the colder months. Another big concern with a deck foundation is making sure the deck posts are installed below frost level and properly concreted to prevent movement or heaving during fluctuating temperatures. You will also want to ensure the deck is level and not pitched away from your house. 

Concrete Pad/Slab:

This is a simplistic greenhouse foundation, but may be a little more costly. Typically, this option is more durable and cleaner looking. With this option a concrete pad with footers is poured usually 6” wider and longer than greenhouse dimensions.  Typically requires concrete footers that go below the frostline to prevent movement during temperature fluctuations. 

Concrete Perimeter:

A concrete perimeter with footings is poured roughly 10”-12” wide (depending on greenhouse frame) where the greenhouse base frame sits. These types of foundation have the same size and shape of the greenhouse but they are not filled in like a slab. They are basically just an outline that supports the greenhouse. The greenhouse is then anchored directly to the concrete perimeter. As with a concrete pad this option is durable and helps prevent the foundation from moving due to weather changes with footers that are below the local frostline. 

Stem Wall/Knee Wall 

This option typically has a concrete footer with a stone, concrete block wall or solid concrete poured wall. Some choose to face the block with a decorative stone and capstone. If you choose not to use a capstone make sure the top of the wall is solid and level. Rebar or anchors cemented into the wall are not needed for anchoring. This foundation option is one of the more expensive but most aesthetically pleasing. It is also durable and can last for a very long time if done correctly. This option is preferred because it can help with heating in the colder months. The sun heats the wall up during the day and slowly releases the heat once the sun goes down. This is only helpful for supplemental heating, not to be used as the only heat source. 

*If going with this option, you must ensure the height of your wall from the finished floor to top of wall matches the drawing. This is needed for the door drop. We can discuss and help further if you have questions. AGMW does not install any foundations. We recommend you hire a locally licensed contractor to complete that portion of the build. We are more than happy to speak with you and/or your contractor to make sure the wall is the correct size and thickness so that greenhouse sits on the foundation correctly.

What kind of flooring should I consider or use?

If you prepare the ground properly and think about flooring materials, you won’t have a lot of issues with drainage, water puddles and function. Proper ground prep will avoid a bunch of issues in the long run.  It is recommended to use a weed barrier below the flooring if using dirt or stone.  There is no right or wrong answer, it’s all personal preference. 

Common Floor Choices: 

Bare Dirt:

Would be used to plant directly into the ground or using raised beds. Some find this option to be messy and that it makes it hard to maintain a clean environment within the greenhouse. 


Many people like this option because it easier to keep clean. You can spray it with a hose and scrub it. This option can be more expensive than others. You will want to consider drainage and if a French drain or another type of drain will be needed. 


It’s clean, easy to get, it’s somewhat easy to make it level, and it drains well.

The material you use depends on what you have available locally and for your budget. Most people go for any type of pea gravel and then add some larger rock or pavers for the walkways.

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