mmolyson

2016 Harbor Freight Greenhouse question about base assembly.

Margaret Molyson
4 years ago

I watched several videos on YouTube before buying my HFGH and they all used lumber under the base plate. My model is #93358 and it tells me to excavate an area for the base, place the metal base directly on the ground, then fill the area with gravel up to 1" from the top of the base plate. No wood is used. Is this strong enough? I'm concerned with my ability to make the ground perfectly flat to support the frame without using wood. On the other hand, I don't know if the base plate can be attached to wood or if the wood would eventually rot, treated or not. Comments?

Comments (7)

  • Margaret Molyson
    Original Author
    4 years ago

    Thanks for the advice. I am concerned about the wind, anchoring it is a must.

  • mudhouse
    4 years ago
    last modified: 4 years ago

    Hi Margaret,

    You have the same model 10x12 Harbor Freight greenhouse that I do. Ours has been up for almost 9 years now.

    I totally agree with kudzu9; it needs to be anchored to the ground. I know the Harbor Freight manual still indicates you can set the frame on the ground and fill it with gravel, but my latest version of the manual also has a page up front, with bold type, that says "IMPORTANT - Wind conditions vary from site to site...may affect practicality of anchoring methods substantially...it is always your responsibility to ensure that the greenhouse is properly anchored...etc." This is because many Harbor Freight greenhouse owners have had their completed structures roll across the yard and be destroyed...when they are not anchored.

    Here is a link to the blog we did about building our HF greenhouse. There's a section on how we did our foundation. As you've noticed by watching videos, there are many ways to tackle anchoring the base...but it really must be securely anchored.

    Building our Harbor Freight 10x12 Greenhouse



    The other thing the manual doesn't tell you is that the panels must be attached to the frame more securely than the kit specifies. If you browse Harbor Freight threads in the archives here, you will also find threads about greenhouses that were destroyed when one or two of the panels blew out, in a wind. If the wind is strong enough, it can then rush inside the structure and bend the soft aluminum frame so it's not salvageable.

    I suggest using extra clips (order them by calling the toll free HF
    number) and by using one or two screws in each panel, going into the
    aluminum frame. The above blog shows how we did that, too. Some people
    prefer to caulk their panels in place, but I never did because I like
    the ability to remove and replace the panels easily.

    So Goal One is to anchor the structure well, and Goal Two is to anchor the panels to the structure well.

    When we built our kit, the 10x12 was fairly new, and there were a lot of Gardenweb forum members building them. So, there were lots of us brainstorming solutions about how to strengthen the kit. I gathered many of the great ideas from this group and put them in our blog. I really suggest reading it, because I want you to have only happy adventures with your greenhouse! There are a number of modifications that will help it to be safer and stronger. None of them are expensive, they just take a bit of time.

    Treated wood is better than untreated for a foundation, especially if your climate has even average moisture. Some folks have even built masonry foundations for these greenhouses. It does need to be flat, though, as you'll have problems with the rest of the build if you don't get the foundation flat and the initial pieces put together in a way that is square and plumb. My advice is to take your time. If you need to, maybe consider asking a friend (or hiring one?) to help you with the foundation.

    I hope this helps a bit. Please feel free to post back, or contact me directly if I can be of more help!

  • Margaret Molyson
    Original Author
    4 years ago

    Thanks so much for taking the time to respond. I appreciate all the advice and will get some help leveling and anchoring the base and will as secure the panels. I'm in no rush, just working very early in the morning and very late in the evening so I want to get it right. Thanks again.

  • mudhouse
    4 years ago

    Sounds good! I have thoroughly enjoyed my greenhouse, and I'm sure you will too. Just a few things to "tweak" along the way, during the build, to overcome a few inherent weaknesses of the kit. Best of luck with your build!

  • sandra r
    4 years ago

    We dug holes in the ground, and used all thread with nuts and washers in the holes and concreted them in ( like tie downs) and then put down 5x6 treated lumber and drilled holes through them and and the all thread came up through the holes, we drilled holes into the 5x6s so the all thread would be counter sunk and put boltes on the all thread to secure the 5x6 frame to the ground, we then put the greenhouse metal base down and used flat stock metal in the bottom channel and drilled holes in it then screwed the base frame to the 5x6s, and then used self tapping screws to put the next part that holds the panels in ....it has withstood some crazy Oklahoma storms this year...:-)....if I knew how to post pictures I'd show ya...my explaining isn't so descriptive

  • mudhouse
    4 years ago

    I think that's a good explanation, sandra, and it sounds like a good solution. Glad to know your greenhouse has survived storms!