Greenhouse Foundation vs Base vs Floor

It seems that there has always been a lot of confusion about what goes at the “bottom” of your greenhouse. A lot of people use these three terms interchangeably. This is not true at all. Each of these 3 items is a different component of a greenhouse.

The greenhouse foundation and base pretty much serve the same purpose. They are used to give a good strong substructure to place the greenhouse on. They also help tie the greenhouse to the ground.

A greenhouse floor is another item all together. It is basically like the floor in your house.

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Greenhouse Foundation

A greenhouse foundation will be built much like any foundation you are building for your home, a garage, a shed, etc. This will all depend on your location.

Many of us have freeze/ thaw cycles that cause the ground to heave and could potentially cause damage to our greenhouse frame and / or covering. In order to build this properly you must go below your frost line and pour a footer or build a pier type foundation with Sonotubes. They have complete instructions on their website (sonotube.com) if you are not familiar with this type of construction.

If you are not sure of the proper level you need to dig down to you can contact your building codes department, or possibly a local contractor.

This is a good practice for any glass greenhouse, but you can build up to a 8 x 12 single glass greenhouse without a foundation. You really want to be sure to build a proper foundation if you are building a double glass greenhouse and a larger single glass greenhouse.

Also, any polycarbonate greenhouse over 12′ x 16′ should have a foundation. A foundation is also a good idea anytime you are attaching a greenhouse to your home or building although a lot of people will use a base with smaller polycarbonate kits.

Greenhouse Base

These are available with some of the kits on the market today. There are also some polycarbonate greenhouse manufacturers who recommend this method. A greenhouse base will be the same size as the perimeter of your greenhouse.

A kit may have a steel base, or you may choose to build your own treated lumber base. It does not come with a floor and it does not go below ground typically. The greenhouse is tied to the base and the base is then anchored into the ground. This helps to stabilize the greenhouse and keep it from getting blown over in heavy winds.

You can build a base like this for a small single glass greenhouse (up to 8′ x 12′) or for a polycarbonate greenhouse up to 12′ x 16′. With some of the kits it also serves a double function. Some of the kits require this for the doors to open properly.

Greenhouse Floor

The greenhouse floor is quite simply what you walk on. There are a whole lot of options for this. Some will choose to do a concrete floor. If you are going to do this you must address drainage when pouring the floor. Also, I suggest using a heavy broom finish, as wet concrete can get slippery.

A second option is to put ground cover down on a leveled dirt surface. This is a UV protected polypropylene material. You may have seen this at some commercial greenhouses. It is the black fabric with green stripes where they have their liners set up. It is a heavy durable material.

You can go one step further and put sand or gravel over top of the ground cover. You can also put pavers down the middle for a nice walkway. The possibilities are endless.

Some people will choose to actually build their raised beds in the greenhouse. If you are doing this you would just use the ground cover or concrete between the beds.

I have had one customer who built an intricate paver pattern inside the entire greenhouse. This is great because it is beautiful, and it is excellent as far as drainage is concerned.

Paver Floor Greenhouse

In Conclusion

Hopefully this will clear up some of the confusion on the differences between a greenhouse base, foundation and floor. You have spent a lot of time, money and studying to find the perfect greenhouse, so be sure to build it properly so it will last a good long time.