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Elevated Garden Bed

Step 1 – Go Shopping

Item
Used For
Quantity
4 x 4 construction grade lumber
3½” x 3½” finished size
Cleats and legs – Parts are not in contact with dirt so treated is OK
1 pc x 8′ long
1 pc x 10′ long
2 x 8 construction grade lumber
1½” x 7½” finished size
Side boards, end boards, cross beams
4 pc x 10′ long
5 pc x 8′ long
2 x 4 construction grade lumber
1½” x 3½” finished size
Support strips
3 pc x 10′ long
1 x 6 construction grade lumber
¾” x 5½” finished size
Rip to 2¾” for bottom slats and support strip batten boards
7 pc x 10′ long
1 x 4 Grade 2 lumber
¾” x 3½” finished size
Grade 2 is recommended here because fish plates need to be free of big knots
Fish plates and spacers – Parts are not in contact with dirt so treated is OK and an easy way to get Grade 2. Check out Menards Model Number 1110203 (SKU: 1110203)
25 lineal ft
¼” x 3½” spacer material – plywood, OSB, flooring, etc
Spacers
4 lineal feet
½” x 5½” plated hex bolt
Assembly of center support cleats
Assembly of center support beam
12 pc
½” plated hex nut
See above
12 pc
½” plated washers
See above
24 pc
⅜” x 6″ plated hex bolt
Assembly of leg cleats and end cleats (32)
Assembly of legs and cross beams (24)
Assembly of end boards (16)
Assembly of middle support strip (8)
80 pc
⅜” x 8″ plated hex head lag bolt
Assembly of support strip batten boards
8 pc
⅜” plated hex nuts
See above
80
⅜” plated washer
See above
168 pc
#10 x 4″ Torx head construction screw
+80
Miscellaneous assembly

Step 2 – Precut Some Stuff

By necessity, a lot of the cutting takes place at assembly, but some items can be precut

  • 2 x 8 side boards (4 req’d) – Cut the four 10 footers to 9′ 6″. If the end of the uncut board is not square and sound, start by making an extra cut to true it up.
  • 2 x 8 end boards (4 req’d) – The end boards should be full 48″ long with ends nice and square. To work around variation in raw material, cut one end board from each of four eight footers. The cut-offs will be a little short which is fine for the support beams. Mark the end boards clearly and separate them so they don’t get mixed back in with the support beams which will look very similar.
  • 2 x 8 beam boards (5 req’d) – The cut-offs from the previous operation furnish four of the beam boards. Make the fifth beam board by cutting the remaining eight-footer in half.
  • 4 x 4 cleats (10 req’d) – Cleats are 16″ long. One end is square and the other is cut at an angle so that the upward-facing end sheds water. The builder can do what he/she wants with the angle. I choose to make the cut at 22½ degrees because my chop saw has a positive stop there.
  • 4 x 4 legs (4 req’d)- Legs are 10″ long. The entire weight of the bed sits on the leg, so make sure the ends are nice and square.
  • ¾” x 2¾” x 44″ for support strip batten boards (2 req’d) – After ripping all 1 x 6 x 10′ boards to 2¾”, pick some really good stuff for these two pieces
  • ¾” x 2¾” x 37¾” for slats (38 req’d) – After ripping all 1 x 6 x 10′ boards to 2¾” and making the two support strip battens, cut the rest to 37¾”. Should come out to 40 pieces.
  • 1 x 4 fish plates for attaching legs (8 req’d) – These pieces are 24″ long. Tweak the location of the cuts so the plates wind up free of serious knots or other defects.
  • 1 x 4 fish plates for attaching center beam board (4 req’d) – These pieces are 16″ long. Tweak the location of the cuts so the plates wind up free of serious knots or other defects.
  • ¼” x 3½” x 7¼” long spacers for assembling legs and beam boards (12 req’d)
  • ¾” x 3½” x 7¼” long spacers for assembling center beam board (4 req’d)

Step 3 – Make Two Side Assemblies

Use five crossways cleats to tie the upper and lower side boards together. Each assembly consists of:

  • 2 pc – 2 x 8 x 9′ 6″ side board
  • 5 pc – 4 x 4 x 16″ cleats
  • 16 sets – ⅜ x 5½ hex bolt with nut and 2 washers
  • 4 sets – ½ x 5½ hex bolt with nut and 2 washers

Start by attaching a cleat at each end of the side boards. The safest and simplest approach is to arrange the side boards on 4″ blocks (having some space between the workpiece and the floor makes room for clamping and also prevents damage to drill bits).

  • Decide which edge of the assembly will be the lower and which the upper
  • Arrange and clamp the parts with the flat end of the cleat hanging over the lower edge 1¼”. Make sure the side of the cleat is flush with the ends of the side boards.
  • Drill and bolt everything together using 8 of the ⅜ x 5½ bolt sets.

Next attach a cleat at the middle of the partially completed assembly:

  • Arrange and clamp the parts with the cleat accurately centered between the two end cleats and the square end of the cleat hanging over the lower edge 1¼”.
  • Drill and bolt everything together using 4 of the ½ x 5½ bolt sets. NOTE USE OF ½” BOLTS ON THIS ITEM

Next attach cleats one quarter and three quarters of the way along the partially completed assembly:

  • Arrange and clamp the parts with the cleats accurately centered between the end cleats and the center cleat. The square end of the cleat hangs over the lower edge 1¼”.
  • Drill and bolt everything together using 8 of the ⅜ x 5½ bolt sets.
  • 1 pc – 4 x 4 x 16″ cleat
  • 2 pc – 1 x 4 x 24″ fish plate
  • 2 sets – ½ x 5½ hex bolt with nut and 2 washers. NOTE USE OF ½” BOLTS ON THIS ITEM

Step 4 – Put Together the Basic Box

Here’s where our pile of long skinny pieces becomes a box. Obviously this will cause the workpiece to get a lot bigger so give yourself plenty of room. It also helps if the surface you are working on is level. The basic box assembly consists of the following components:

  • 2 pc – Side Assemblies per Step 3 above
  • 4 pc – 2 x 8 x 48″ end boards
  • 16 sets – ⅜ x 5½ hex bolt with nut and 2 washers

The more care we take to align things carefully at this stage, the smoother final assembly will go and the better the box will function. The important thing is to stay organized and not rush. Align all the parts carefully and clamp securely before doing any drilling or bolting. Here’s the sequence that was used to build the prototype:

  • Start forming the box by laying the two Side Assemblies flat on the floor about four feet apart. Make sure the cleats are on top with the angled end pointed inward.
  • Roll one of the Assemblies up on edge (angled end of cleat pointed up) and hold it in that position by clamping one of the 2 x 8 x 48″ end boards to the end cleat. At this point the board is only functioning as a temporary brace. Even though the parts will be repositioned and attached permanently later, the horizontal alignment is important now. The ends of the brace need to be flush with the outside of the cleat.
  • Roll the other Assembly up on edge, slide it into position against the brace and clamp it as was done with its twin. Just for the heck of it, let’s call this the north end of the box.
  • Move to the south end of the box and clamp a 4 x 8 x 48″ end board to the end cleats of both Side Assemblies. Let’s refer to it as the bottom end board. Align it horizontally by bringing the ends flush with the outside of the end cleats. Align it vertically by bringing the bottom edge flush with the adjacent side boards.
  • Drill and bolt the end board in place using 4 of the ⅜ x 5½ bolt sets.
  • Staying at the south end of the box, clamp another end board above the one just described. Let’s refer to it as the top end board. Clamp, drill and bolt it in place using 4 of the ⅜ x 5½ bolt sets.
  • Go back to the temporary attachments at the north end of the box. What had been the brace holding the two Side Assemblies in position becomes the bottom end board. Realign and clamp it as was done at the south end.
  • Drill and bolt using 4 of the ⅜ x 5½ bolt sets.
  • Staying at the north end, position and clamp the top end board.
  • Drill and bolt using 4 of the ⅜ x 5½ bolt sets.

Step 5 – Reorganize

Turn the workpiece upside down (angled end of cleats pointing down). As you turn it, pay attention to how heavy it is and realize that the weight will more than double before you finish. Step back and get a handle on how big it is. Accept that a workpiece this big and awkward has some extra safety issues and reorganize your workspace accordingly.

Step 6 – Add the Side Floor Supports to the Basic Box Assembly

The boards that form the floor of the box are held up by 2 x 4 supports that run the length of the box. This step addresses the two supports that run along the sides of the box and support the ends of the floor boards. A third support strip that runs down the center of the box is discussed later.

  • Position a 2 x 4 x 10′ long stick on top of one of the edge boards so that the excess length hangs over evenly on both ends.
  • Use clamps as needed to jack the support strip tight against the backside of each of the cleats. Use construction screws every 3 – 4 inches to attach the strip to the side board.
  • Repeat for the second outside support strip.

NOTE: This write up assumes 10 foot long sticks will be used. Some builders may want to piece the supports together from shorter sticks. That’s OK as long as the basic geometry stays the same and the cut lengths are tweaked to make seams land on cross beams.

Each of the four leg cleat assemblies consists of:

  • 1 pc – 4 x 4 x 16″ cleat
  • 2 pc – 1 x 4 x 24″ fish plate
  • 2 sets – ⅜ x 6 hex bolt with nut and 2 washers

Arrange the parts on a flat surface as shown. clamp securely, drill and bolt.

Step 4 – Make the Center Cleat Assemblies

Each of the two center support cleat assemblies consists of:

Arrange the parts on a flat surface as shown. clamp securely, drill and bolt.

The cleats and cleat assemblies are used to tie the upper and lower side boards together. Each of the two side board assemblies consists of:

  • Arrange and clamp the parts with the flat end of the cleat toward the builder and hanging over the edge of the lower board 1¼”. Make sure the assembly is accurately centered between the two end cleats.
  • Drill and bolt everything together using 2 of the ½ x 5½ bolt sets. NOTE USE OF ½” BOLTS ON THIS ITEM

Attach the Leg Cleat Assemblies to the side boards (positions 2 and 4):

  • Arrange and clamp the parts with the flat end of the cleat toward the builder and hanging over the edge of the lower board 1¼”. Make sure the assemblies are accurately centered between the end and center cleats.
  • Drill and bolt everything together using 4 of the ⅜ x 5½ bolt sets.

Step 6 – Make the End Cleat/End Board Assemblies

The end cleats are used to tie the upper and lower end boards together. Each of the two side board assemblies consists of:

Step 9 – Add the Middle Cross Beam to the Basic Box Assembly

The box and it’s contents exert roughly 500 pounds of downward and outward forces on this set of components. That’s why the construction is extra sturdy. Alignment is especially important here, especially making sure that the beam is tight against the floor board support strips.

  • Set the 2 x 8 beam board into the gap between the fish plates. It will be a little short so even up the gap at the ends.
  • Center the beam between its fish plates, using two ¼” and two ¾” spacers on each end of the beam.
  • Jack the side boards around as needed to get them square with the beam and take out any bowing that may have occurred. I suggest using furniture clamps to draw the beam tight against the support strips.
  • Drill and bolt using 2 of the ½ x 5½ bolt sets at each end of the beam. NOTE USE OF ½” BOLTS ON THIS ITEM

Step 10 – Add the Cross Beams and Legs to the Basic Box Assembly

Two sets of cross beams and legs will be added. Each set consists the following items:

  • 2 pc – 2 x 8 x approximately 48″ long cross beam board
  • 2 pc – 4 x 4 x 10″ long leg
  • 4 sets – ⅜ x 5½ hex bolt with nut and 2 washers
  • 4 pc – ¼ x 3½ spacer

These components have a big job to do. The dirt filled box that sits on top of them weighs over 2000 pounds. But holding up all that weight is manageable if we get a principal called “direct bearing” working for us. We do this by putting the parts together in a way that the box sits directly on the cross beams which sit directly on the legs which sit directly on the ground. The fasteners don’t have to carry the weight of the box, they just have to hold the parts in the correct relationship with one another. So we need to see that all the parts are carefully aligned while they are being put together:

  • Set two 2 x 8 cross beam boards into the gap between the fish plates. They will be a little short so even up the gap at the ends.
  • Center the beams between the fish plates, using two ¼” spacers.
  • Jack the side boards around as needed to get them square with the beam and take out any bowing that may have occurred. I suggest using furniture clamps to draw the beam tight against the support strips.
  • Drill and bolt using 2 of the ⅜ x 5½ bolt sets at each end of the beam.
  • Set a 4 x 4 x 10″ leg piece between the fish plates at each end of the beam. I suggest using furniture clamps to draw the leg tight against the beam.
  • Drill and bolt using 2 of the ⅜ x 5½ bolt sets to secure each leg.

Step 11 – Add the Floor Board Center Support to the Box Assembly

The boards that form the floor of the box will be attached to support strips that run the length of the box. The strips that support the ends of the floor boards were discussed earlier. There is a third strip that runs down the center of the box and will support the floor boards in the middle.

  • Position a 2 x 4 x 10′ long stick on top of the two end boards. The piece will sag badly because the boards it’s sitting on are ten feet apart. I suggest tying the piece up against the center cross beam to help it stay put.
  • Tweak the side-to-side alignment of the Center Support so that it is centered on the end boards. Tweak the end-to-end alignment of the piece so that the excess length hangs over evenly on both ends. I suggest screwing down the ends to keep the piece from skating around.

Step 12 – Add the Batten Boards to the Box Assembly

The middle portion of the box and its contents is supported directly by the three cross beams. The batten boards provide extra reinforcement out at the ends where there are no cross beams.

  • Position one of the ¾” x 2¾” x 44″ long batten boards across the support strips at one end of the box so that it is centered above the end board that the support strips are resting on. Tweak the side to side alignment so that the overhang is about the same on both ends of the batten board.
  • Clamp securely, drill and bolt using 4 of the ⅜ x 8 lag screws.
  • Repeat for other end.

Step 13 – Add

It’s time to turn the box assembly right side up and add the last few components. At this point the box is being held together by the lower end boards.