Preparing a Greenhouse Foundation: Everything You Need to Know

Do all greenhouses require foundation?

The simple answer is YES

Over the years we have had hundreds of greenhouse-related questions and many of them are related to foundations.

Some things to know:

1. Your greenhouse foundation needs to be prepared by the homeowner.
2. Our greenhouses have unique sizes so please be sure to build to the exact outside dimensions. For example, an 8x12 greenhouse is actually 8' 7 1/2" x 12' 8 1/2".
3. The foundation MUST be level and square.
4. You can build a greenhouse on a sloped year.

Things to Consider Before You Build:

Selecting the Best Site for Your Greenhouse

• You will need a minimum of 6 hours of winter sun or supplemental lighting will be necessary.
• Easy access will be appreciated for years to come for bringing in plants, soil, fertilizer etc.
• A flat, level surface is ideal but not totally necessary
• Are there large trees nearby that need to be considered for dropping branches?
• Is it a high traffic area? Do you need to think about setback rules from your municipality?

A Freestanding or Home-Attached Greenhouse?

Freestanding Greenhouse

This will allow you to place the greenhouse according to the best sun exposure.

Home-Attached Greenhouse

This option will give you great access to utilities and heat gain from the existing building

Greenhouse Flooring Options

The floor of your greenhouse is up to you. Some options include concrete, gravel, pavers, mulch, brick, soil or compressed sand. One thing to consider is that the organic materials listed will easily attract pest and if you have an infestation, you will need to disinfect and replace the flooring.

The most economic and common flooring we see is a layer of weed screen, crushed gravel with paving stones down the centre. It's great for drainage and easy to clean!

Here is a slideshow of flooring options sent in by our customers:

Wood or Concrete?

The most common foundations for hobby greenhouses are wood or concrete. Wood is the most popular choice because it is easy to work with and easy on the pocketbook. The other benefit is that wood can easily be adjusted down the line if you decide to move or extend your greenhouse.

A concrete Greenhouse foundation is more permanent, of course, and depending on the greenhouse you select, will become a part of your landscape for generations. Other common greenhouse foundation materials include cinder blocks or bricks. Believe it or not, we have also seen a terracotta foundation that looked pretty great!

Seven Questions to Ask Before You Break Ground:

1.  Do you require a permit?
2. Will you require engineered drawings?
3. Where is your water access?
4. What are your power requirements?
5. Is your yard level?  How do you access the site for installation?
6. What do you need for drainage?
7. If you need concrete, how deep does the concrete need to go?

For a breakdown on the questions above plus more details on how to build a foundation (wood, concrete and more), approximate costs, greenhouse flooring ideas and more please view The Essential Guide to Greenhouse Foundations. 

For more specific advice, feel free to connect with our team anytime at 1-888-391-4433 or hello@bcgreenhouses.com