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Simple Concrete Raised Garden Beds – Part 1

By June 8, 2020November 24th, 2020One Comment

Make your own concrete raised garden beds! Build the forms and cast your own concrete panels that join together to make long lasting and durable garden boxes. This is Part 1 of this mini-series and the 4th version of the forms and panels.

I’ve been thinking about the design of the form for the concrete raised garden beds panels I’ve been casting. I want the forms to be easier, and faster to build, especially for those with little or no woodworking experience or tools. And I also want the casting process to be easier. And I think I got it with this new version of the forms. See Part 2.

See the Youtube Video and download the Plans.

How much concrete does it take to pour each size of panel? 
Here’s the approximate square foot volume for this 2” thick panel:
36” panel  = 0.363 cu ft
Bags of ready mix concrete are sold in various sizes. Here is how much a bag of Quikrete will make:
40lb bag = 0.30 cu ft
50lb bag = 0.375 cu ft
60lb bag = 0.45 cu ft
80lb bag = 0.60 cu ft
Check the instructions on the bag to see how much it makes.

Background for the SUPER Simple Concrete Raised Garden Beds Project – PART 1

(this is a transcript from the video)

The concrete garden panel forms I’ll be making today are about as simple as I can design them. They still create a great panel that is long lasting and rot proof for your concrete raised garden beds. And they still link together and can be be arranged in a number of shapes and sizes.

Concrete Garden Box Simple Form - graphic of assembled garden box

These Garden Box Panels link together to make a range of custom shapes and sizes.

And these can also be stacked to make taller beds.

You won’t need a lot of tools to make these new simplified forms. Only a few hand tools and a drill. I’m taking things right down to the basics here, to show you the bare minimum you need to do build the forms and cast the concrete panels. You won’t need a table saw, or a drill press, or any other power tools.

I have a new set of plans and have them available for download. These plans will also have a more detailed list of materials and step by step instructions.

This will be a detailed tutorial. So if you are an experienced woodworker then maybe this video is not for you. But, I’ll be trying some new ideas here that can also be applied to the other forms I’ve designed.

So here’s how these new simplified forms go together:

Concrete Garden Box Simple Form - Kent with wooden form and concrete panels pinned together

jump down to the  Cost Breakdown section below

The base is made from a 2 by 10 and acts as the bottom of the form and the support for the 1 by 4 walls.

Sketchup animation of concrete panel mold parts

Each end is assembled from three pieces with the middle piece having a hole to support a pipe.

Sketchup animation of concrete panel mold parts

The sides have a hole for the other end of the pipe.

Sketchup animation of concrete panel mold parts

The pipe is PVC plastic and forms the holes in the casting.

Sketchup animation of concrete panel mold parts

Once hardened, the pipes are slid out of the casting through the sidewalls.

Sketchup animation of concrete panel mold parts

The form is turned over and the casting removed.

Make the BASE of the form for the Concrete Raised Garden Beds

Selecting lumber to build concrete forms

If you’re at all intimidated by woodworking — don’t worry, I’ll go through everything you need to do.

Selecting lumber to build concrete forms
The lumber for these simplified forms are all standard sizes and can be bought at any big box hardware store or lumberyard. Look for boards that are straight and flat without any twist or any cracks — and few if any knots. Try to select the best ones you can find even if you have to sort through a pile.

Good lumber will make everything easier so it’s worth it to be fussy here. I’ll look at the condition of the end of the 2 by 10 and 1 by 4.

Selecting lumber to build concrete forms

I want to avoid any cracks.

Selecting lumber to build concrete forms

I also want to check the width of the board. It should be 9-1/4″.

Cutting the base lumber for the concrete form

And I’ll check if the ends are cut square. If so, then I’ll take advantage of that for one end of the base.

Cutting the base lumber for the concrete form

I’ll make a point 4-5/8″ from one side. This marks the center line of the board.

With my square on the end, I’ll draw a line in a couple of inches.

Cutting the base lumber for the concrete form
I’ll try to indicate metric equivalents where possible. The plans have dimensions in both inches and millimeters.

Cutting the base lumber for the concrete form

I’ll make another mark two inches in from the corner and draw a line with the square.

Cutting the base lumber for the concrete form

This is the corner I’ll be removing.

Cutting the base lumber for the concrete form

I also trace these lines around each edge to the other side. This will help me check that I’m sawing straight and square.

To make the base I’ll be using two hand saws, a regular saw and a finer tooth stiff-back miter saw, a pencil or a pen, a measuring tape, and a 12-inch combination square.

From an eight foot two by ten, two eight foot one by fours, and a four foot length of three-eighths pipe, you can build two 36 inch forms.

I support the board over sawhorses. You could use some chairs for this as well.

Cutting the base lumber for the concrete form

I use the fine miter saw to make the first cut two inches in from the end of the board. Part way through these cuts you can stop and turn the board over to see how you’re doing. And to make some adjustments as you go.

I’ll start the other cut with my miter saw it has a stiffer blade and it’s easier to get off to a good start with.

The 36 inch panel I believe is the most versatile size for a garden bed  but, you can make the panel’s any length you like. The concrete raised garden beds can be any size you want.

Cutting the base lumber for the concrete form

With the larger handsaw I finished the cut to remove this corner.

Cutting the base lumber for the concrete form

I checked these cuts with my square. And they looked okay.

Cutting the base lumber for the concrete form

Next, I’ll measure 36 inches from the end and mark around the board with pen and square.

Cutting the base lumber for the concrete form

I marked this side of the board as the “bottom” then cut the board along this line. Then mark the cutout on the opposite corner.

Cutting the base lumber for the concrete form

And as before, make these two cuts. I checked these cuts with the square and use some medium grit sandpaper, wrapped around a block of wood, to fix any cuts that were not so straight or square. Don’t over worry much, just try to follow your lines as best you can.

Make the SIDES – Form for concrete raised garden beds

Now that we have the base done we’re gonna cut the sidewalls from an 8-foot one by four, and here’s what we need to do that.

Concrete Garden Box Simple Form - the basic tools needed

A miter box and a miter saw, a drill, and if you have one a driver (but a drill is probably all you need), Phillips screwdriver, three drill bits: 1/2″, 3/16″, 1/8″, some wood glue, and a bit of medium to coarse sandpaper. Two sizes of screws: drywall screws: #6 1-5/8″ and a #7 1-1/2″  pocket, or cabinet screws, flathead. And we’re going to use a tape measure, a square, a drill block, a pen or pencil, and a scrap piece of wood.

From the concrete raised garden beds plans we’re gonna make all the cuts for the side walls and for the end assembly pieces. We’ll need two of each. What I want to do is with my miter saw screwed to the workbench, I’ll check the end of this 1 x 4 to see if it is square.

Cutting the sides and ends of the form with simple tools

If it’s square then I can use that end.

Cutting the sides and ends of the form with simple tools

I’ll mark the first cuts. Both the side walls are 35 1/2″ and I’m going to mark and cut one at a time.

Cutting the sides and ends of the form with simple tools

This particular miter box has these little pegs here to help hold the workpiece while I’m cutting. Which is kind of handy. I know it’s a little bit of a flimsy box but for this type of project it’ll do just fine.

I marked my line 35-1/2″ and I want to cut on the right side of that line. And then what I’ve been doing just a little bit of a little sandpaper you have that on a sanding block that works for you.

Cutting the sides and ends of the form with simple tools

That’s the first and then we’ll take another 35-1/2″ and then we’ll have our side walls for our first form.

Cut END ASSEMBLY pieces

Then it’s a matter of taking what’s left from the 1×4 and cutting the parts for making up the end assembly. So there would be six parts altogether.

Cutting the sides and ends of the form with simple tools

Drill HOLES in SIDES and ENDS

Now we’re going to drill the holes for the dowels(pipes) in parts D and in the end walls so the first thing to do is lay those out with the measurements.

Cutting the sides and ends of the form with simple tools

We know that we’re coming down one inch and then on the D parts one and three-quarters in on the sidewalls. Also one and three quarters from the other end.

Cutting the sides and ends of the form with simple tools

This is going to be a half inch hole I’ve got a half inch bit in my drill.

And the little drill block that I have by Milescraft this is really handy. This is basically replacing a drill press for us.
It has holes going from 1/2″ down to 1/8″ which is perfect for us. And also it has these small alignment grooves that’ll help us position our drill block exactly where we need it to drill exactly in the center of that hole.

Cutting the sides and ends of the form with simple tools

So I don’t drill into my workbench, I’ve got a scrap piece of lumber for this. I just kind of sight down that and basically just hold it in place and go nice and easy.

Cutting the sides and ends of the form with simple tools

Drill assembly PILOT HOLES

Now I’m going to lay out the locations of the pilot holes to make up the end wall assembly as well as where they will attach to the base.

Cutting the sides and ends of the form with simple tools

So let’s start with Part D and I know that D I’m going to come in a 3/8 of an inch down the side and 3/4 of an inch from the top and the bottom.

I can set this ahead of time to my 3/8 mark and then I can use this a scrap piece here as a 3/4 inch marker for parts D here so I know I’m going to be coming down on D 3/4 of an inch and 3/4 of an inch up from the bottom and then D’s going to attach on this side 3/8 in.

Cutting the sides and ends of the form with simple tools

I have the spots marked for the pilot holes because D is going to go together with Part C and II like to make an end wall assembly like this so I’m going to need to drill pilot holes to go through this direction as well as pilot holes for screws that are coming in this direction here so it’s a matter of just laying out those holes.

Cutting the sides and ends of the form with simple tools

And with 1/8 bit just drill in the pilot holes. Now the drill block also has a 1/8 inch guide here but I think for this size a hole and what it’s doing here just free-handing these would be fine.

So that’s going to put the screw right in the center of the other piece.

Cutting the sides and ends of the form with simple tools

All right so that’s D and then with let’s say Part E when I look at that one I only have one that I need to worry about and it’s the screw that’s going to hold it through the bottom wall into a piece like this which would be the base and that one is 3/4 inch up from the bottom. And somewhere in the center the pilot hole for each.

Now I’ll do the pilot holes for the sidewalls and 3/8 in from the sides. Okay and we’ll do the same with the other side wall.

Assemble the END WALLS – Form for Concrete Raised Garden Beds

Here’s where we’re going to assemble the end wall pieces together and we’re going to use some #6 1-5/8″ drywall screws put them together with and a little bit of wood glue.

Assembling the form parts

If you’ve got some exterior wood glue that would probably be preferable but I think any wood glue would probably be fine.

Assembling the form parts

Use our miter box to help hold some of the pieces together. What I like to do is to just visualize how it’s going to go. So I’ve got my Part B here part and D there and then I’ve got my Part C like that and then what I like to do is where D and E meet I’m going to put two double lines like that and then where Part C and D meet I’m just going to put a single line across that so when I’m moving pieces around to put it together then it’s easy for me to figure out okay which piece was from where right so then I know that these two were meant to go together like this.

Assembling the form parts

What I do is I’m going to hold those pieces and I’m going to use the miter box to help hold it square use my 1/8 bit and just go slightly in two part what is it part E you see just two little starter holes there and I can apply a little bit of wood glue.

Assembling the form parts

Again use these alignment marks to help me remember which way it went take a couple of these little drywall screws and just start them in the pilot holes from Part D.

Assembling the form parts

I’m going to snug those and then I’m gonna check with my fingers to see how this is aligned. It looks pretty good so then I’m going to snug them a little bit tighter by hand. Just so they’re flush with the surface.

DIY Concrete Garden Box - making the ends of the form (Sheet Editor)

Making the ends of the forms, starting the screws by hand

Assembling the form parts

And then Part C is going to go like that so again to just hold it in place through the pilot holes into Part C and a little bit of wood glue.

Assembling the form parts

Set them back in place start the screws check for alignment here and then finish tightening by hand.

I like to do it by hand so then I can kind of get a feel if I’m starting to split any of the wood.

TEST FIT

All the main components are made now it’s time to test fit and assemble the form for the first time. We’re going to start with the ends.

Assembling the form parts

Set them in place basically you want to see how they fit and we want to make sure it doesn’t extend anywhere past here.

Assembling the form parts

Make sure that it fits nicely in the corners as well.

Assembling the form parts

Then we’re going to run screws in through these two sections right there. I’ll use pocket hole or flat head cabinet screws here. These are 1-1/2″. They’re #7 so we can just start those now we’ll go down to the other end to put the other end.  Now test fit this other end see how it fits in the corner.

It doesn’t extend past here. This board must be slightly more than nine and a quarter. So we’ve got a little bit we’re gonna have a little bit of gap when this comes together in this corner but that’s no problem.

Assembling the form parts

Okay I messed up these a little bit. I put D the wrong way around on both of these ends so the glue wasn’t completely set up so I just pulled the screws out, flip this around and put it back together.Now the holes line up properly.

Now let’s just attach the sidewalls, we need to line this edge up to here.

Assembling the form parts

I’ll run in just one screw right now to hold this in place into these ends.

Assembling the form parts

And some screws in here and do the same on this side starting at this edge here because I want these to line up.

Assembling the form parts

We want to see if they can line up. Sometimes they’re a little bit tight and we need to open up this hole a little bit with the half-inch bit.

Assembling the form parts

We’ll just make it a little bit bigger and then we’ll see how this fits.

This lines up pretty well but it’s a little bit snug so I’m going to do the same.

LABEL PARTS

Last thing to do is to label the parts so we can assemble it exactly the same again. This is my second form so it’s going to be labelled “B”.

Labeling the forms parts to aid in disassembly

Apply MINERAL OIL

Now that we know that it fits well together we have all the parts labeled, looks like the holes are aligned properly now we’ll take it apart and coat it with mineral oil.

disassembling the form

You can buy “Butcher’s Block” oil for these. Or straight food grade mineral oil a bit cheaper in pharmacies.

taking parts to be oiled

It’s very fast to apply. Just smear it on and let it soak in. Two coats will do.

applying mineral oil to concrete form

applying mineral oil to concrete form

SEE PART 2

This is a continuation of my series on making these concrete garden box panels.

In the first video I made the forms from plywood. In the second I simplified the design to make the forms easier to build. In third video I cast the panels with lightweight concrete. And in Part 4 I made them thinner using CSA Concrete.

Sketchup animation of concrete panel mold parts

Cost Breakdown

The construction materials total is for making two 36″ forms

(1) 2×10 @ 8 ft = $8.75

(2) 1×4 @ 8 ft = $8.66

(1) 3/8″ water pipe @ 5 ft = $2.25

So for 1 form the total materials to build it is: $9.83

The additional materials to complete the forms

Wood Glue 16oz (473ml) $6.00

Latex Caulking small tube 5.5oz (162ml) $2.47

Mineral oil (Butcher’s Block Oil) 17oz (500ml) $15.00

PAM Cooking Spray 6oz (170g) $3.97

The glue, caulking, mineral oil, and cooking spray are enough for maybe 6 forms so I have estimated the cost for one form to be: $4.57

Concrete

(1) bag of any ready-mix concrete

I used 66lb (30kg) bags @ $6.08 each

This is more than required so there could be more savings to be had when pouring bigger batches. The Cement Dye I used was optional so not added here.

So, to make one panel the cost is $6.08

Minimum Tools Required

Woodworking Tools I used

DeWalt 20V MAX Compact Drill/Driver set $200.00
Hammer $10.00
Miter Box & Saw Set $19.95
Hand Saw $20.00
Drill Block $13.00
Drill Bit Set $24.00
#2 Phillips Screwdriver $5.00
Sandpaper $5.00 (3 sheets)
12″ Combo Square $20.00
Framing Square $20.00
Small Spirit Level $2.97
Measuring Tape $6.00
Driver Bit Set $20.00
Wood or Rubber Mallet $8.00
Mixing Bin $7.68

There’s some real opportunities to save money on tools if you shop around. Or even to borrow some. And, there are cheaper drill/driver combo sets available that would work just fine.

Hardware
Drywall Screws #6 1-5/8″ $4.45 (100 pieces)
Pan Head Screws #7 1-1/2″ $8.91 (250)
Galvanized Framing Spikes 12″ $0.99 each

So I hope you have enjoyed this post, and thank you so much for reading. If I make any further improvements or changes I’ll post them here.

And, while you are here, please hit the Support Link to help us make more projects and videos like this. We really appreciate anything you can do to help us out!

 

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