Turning A Very Large Three Deck Flower Box Into A Deck

by Cheryl Wyatt
(Reading, Pennsylvania)

In my backyard I have a very large three tier flower box in the back of my house next to my concrete walkway that has stairs that lead down to my garage. I was planning on filling this in, levelling it out and making a very nice deck.

I also have a extremely small deck on the side of my house that I wanted to connect to the larger deck is this feasible. My neigbhor who is a carpenter and did his own deck wants to help me put it in. This would save me a huge amount of money. But I do not have any knowledge on how to do this.

Should the flower bed be emptied, levelled out and filled with concrete then covered with the wood.

Any suggestions? Plus what type of wood would be the best longest lasting.

Editor's Comments:

If you are planning on retro fitting a flower bed into a deck you are essentially going to be relying on that structure to function as the foundation and support for the new deck.

I can appreciate the create spirit that is inspring your plan. But I would offer a few comments as you think this through because what you are thinking of doing is potentially problematic.

What Can Go Wrong

Depending on how the flower beds are built and set into the landscape they may be completely incompatible as a load bearing structure. This means the load from the deck might eventually cause the flower bed structure below to sink into the soil or worse - drift down the slope incrementally over the years.

Where To Begin

First take a very good look at exactly how your bed is built and how it rests on the soil. Does it have a footing system supporting it on the grade? Or is it just a series of horizontal landscape 6x6 ties? If so are they tied back into the slope with perpendicular horizontal 6x6s?

A lot of things to consider. But if it is stable enough then you should be able to build on top of it without overloading it.

Filling The Flower Bed

You may have to remove some of the soil to lower its elevation because you do not want to have wet soil in close proximity to the joist structure during the life of the deck.

I would lower it significantly and lay down some landscape fabric and fill back up with crushed stone. This would promote water drainage and reduce the chance of weeds finding a home.

Wood Selection

This all comes down to what your budget is. A good quality cap stock composite would be a deluxe solution so long as you have a good 12" of air flow underneath. Confirm with the manufacturer the recommended elevation above grade.

Treated pine or cedar will also work. But as you know will require annual maintenance. One thing I would do is stain the underside of the decking for extra protection.


If you have pictures of your existing deck it would be great to see them. I am sure others reading this article would want to understand exactly what we are talking about.

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