Children's Triple Bunk Bed

Most bunk beds come in the standard, 2 bed, stacked, format. For most this works, but there are some cases where you might need something more. I have 3 kids and, currently, a house with only one room to fit them in. While a standard bunk bed would take care of 2/3 of the problem... there wasn't enough room to fit another bed in addition to the others. So I knew that wouldn't work. I researched triple bunk beds but they are much harder to find and, from what I saw, mostly stuck with the standard stacked format. Three stacked beds end up being very tall which makes changing sheets (or catching kids that don't want to come down!) very difficult. So I decided to build my own that would be more compact. By off-setting the middle bunk I was able to bring the top and bottom bunks closer together. Overall the space between the beds was reduced so that the top bunk could be reached while standing on the ground (top bed height is 5ft). I made the total space between beds 18 inches. For adults that may feel a little tight, but that only applied to the overlaps where the kid's legs would be. The head space was designed with a much more roomy 42" between bottom and top bunk.

This is a custom build, it was sized to fit the available space and designed to meet my main concern of reducing overall height. I appreciate that the sizes may not work for everyone but the concept is an intriguing one and hopefully you'll be able to at least use the design as an inspiration. In this instructable I will discuss the overall process I went through and some lessons I learned along the way. I will use my specific measurements but of course you could always modify as needed. There are a lot of steps but many are repeated as you essentially end up building three beds. I specifically designed the individual bunks to be close to the same so that I could repeat building steps with only slight modifications. That helped me build a bit faster. This also means that, one day, when the bed may begin to feel claustrophobic for the kids, the spacing between beds can be increased or each bunk can even be separated from each other and used as separate beds.

NOTE: This build is designed around standard, twin size mattresses (39"W x 75"L)

For this build I used the following tools:

Miter saw

Table Saw

Belt Sander (x2....I ended up wearing out and having to retire my Ryobi on this project...OOPS)

Drill

Jigsaw

In this step I will write the full cut list, I'll reference the cuts to be used in specific parts of the build in their respective steps but this way you have it all in one place.

4x4:

45" (x3)

37.5" (x4)

31.5" (x4)

2x4:

71" (x4)

39" (x8)

28.5" (x2)

~150" for corner braces

2x2:

~120" for corner braces

4x8 plywood (.75" thick) - 3x

.75" x 5" (taken from plywood cut scraps)

71" (x2)

39" (x3)

.75" x 1.5" (taken from plywood cut scraps)

61" (x4)

29" (x7)

22" (x2)

There is a lot of wood that goes into this build. It all needs sanding and finishing. You can simplify the task by finishing only the exterior surfaces of the bed (legs, outer faces of frame, corner braces) and skipping the surfaces that will be in-accessible during use (plywood, interior of frame). However the greatest way to simplify this step is to do it pre-assembly. Once the pieces are all cut, cycle through sanding steps up to 150 grit. Then apply polyurethane sealant coats to surfaces that will experience wear during use and allow to dry. You can build the beds and then sand them once assembled but that is much more difficult.

I began the build by working on the bottom bunk. The cut list specific to this part of the build is:

4x4:

31.5" (x4)

2x4:

71" (x1)

39" (x3)

28.5" (x1)

~50" for corner braces

2x2:

~36" for corner braces

4x8 plywood (.75" thick) - x1 -- cut to 73.5" x 42.75"

.75" x 1.5" (taken from plywood cut scraps)

61" (x1)

29" (x3)

22" (x1)

Laying out the pieces cut for this bunk, place a 71" piece of 2x4 with a 39" and 28.5" piece across from it (making the two long sides) and then place a 39" 2x4 at each of the two short sides. The four 4x4's become the legs of the bed at each corner.

Now you may be wondering about why I didnt just use a 71" piece on each of the long sides of the bed... We will discuss this more in detail later but essentially you need to account for the space the legs from the upper bunks take up as they pass through the lower bed frames. I'll call this space allowance the "pass-through".

The 2x4's are mounted to the legs via brackets. The brackets are placed so they hold the 2x4 as it butts into the side of the bed leg. The brackets are mounted with #10 3/4" screws as shown in the images. I purchased the brackets from Lowes:

https://www.lowes.com/pd/USP-1-1-2-in-18-Gauge-Woo...

(I ended up getting about 50 for the entire build)

Attach all the 2x4's to the legs with the brackets. I marked where the top of each 2x4 should line up on the leg and then held the wood in place as I screwed the brackets in place. The distance from top of 2x4 to bottom of each leg is 6.5".

Now for a quick discussion of the "pass-through"

For the middle and bottom bunk, there needs to be a hole cut in the frame of the bunk to allow the leg of an upper bunk to pass through. This is why a single 71" 2x4 was used to make one long side of the bottom bunk while the other was made using a 39" and a 28.5" piece.

39+28.5 = 67.5. The difference between 71 and 67.5 is 3.5. Which, is the actual size of the 4x4 legs (actual dimensions are 3.5x3.5). So the differnce in length is taken up in the width of the 4x4 leg passing through that part of the frame.

At this point in the build, there is no leg from an upper bunk to tie in to the frame. So I just cut off a stump of 4x4 to bolt into the frame so it would all hold together. Later the place-holder will be removed to allow the actual bunk leg from the middle bunk to take its place.

With the basic frame put together, it was time to reinforce the frame corners. These corners will not only support load from the bottom bunk, but they will also need to be stiff to keep the top bunk stable as well.

The corners are reinforced by adding 45 deg braces in each main axis of each corner. First the 2x4's are linked to each other by a 2x2 brace, then the 2x4's are linked to the leg via 2x4 braces.

Braces are attached via 1.5" (for the 2x2 braces) and 2" (for the 2x4 braces) decking screws.

The 2x2 braces need to be around 7" long while the 2x4 braces can be more flexible in their length. I made them about 12" long.

While slats can often be used to support a mattress, I decided to use a solid piece of wood to support the mattress. This is where the plywood comes in. Cut the plywood so it fits just inside the frame you just made. The frame should be 75"x43" but you may need to be just a fraction of an inch smaller to make it fit in smoothly (though ideally you want it to be a snug sort of fit). If you cut a rectangle of that size, however, you will run into problems with the braces/legs being in the way. Cut the corners off of the ply wood so that it fits past the braces. additionally you will need to mark the location of the pass-through and cut out a hole for that

To retain the plywood in place, I built up an interior edge on the 2x4's using the scrap pieces from cutting the plywood. The scrap pieces were about 1.5" wide and went the length of the 2x4's. I made sure to leave gaps near the braces/brackets so I could have room to later access the space with my drill to assemble/dissemble.

I attached the ledge by marking a line 3/4" down from the top of the 2x4 frame all the way around. Then I laid in the strips and used a combo of wood working glue and finishing nails to connect them along their length to the frame.

The plywood rests on the ledge and came flush with the top of the 2x4 frame. Because I used 3/4" thick plywood, it was stiff enough to support the weight of the person using the bed without additional wood at mid-span. I tested it myself, even jumping up and down a bit...cuz you just never know what crazy shenanigans children will get into. The frame and plywood was solid!

Next, I made the top bunk.

The cut list specific to this part of the build is as follows... not much difference with the exception of the leg lengths and no special considerations for any pass-through (as there is no bunk above it)

4x4:

37.5" (x4)

2x4:

71" (x2)

39" (x2)

~50" for corner braces

2x2:

~36" for corner braces

4x8 plywood (.75" thick) - x1 -- cut to 73.5" x 42.75"

.75" x 1.5" (taken from plywood cut scraps)

61" (x2)

29" (x2)

As I mentioned in the previous step, since this is the top bunk you won't have any pass-through's to worry about for this bed. That makes the assembly pretty easy. Again lay out the long and short sides of the bed (two 71 pieces and two 39" pieces) and bolt them to the 4x4 legs via the brackets used earlier. There are a few changes here, as will be discussed in the following steps.

Mark on the legs where the top of the 2x4 pieces will connect to the legs. This happens at 15 inches from the top of each leg. You will need to assemble the bunk up on top of the lower one so I found that was made simpler by assembling the legs and long pieces of the frame and setting them as a unit off to the side until I was ready to assemble. Once in positioned, the shorter ends of the frame could be secured in place to complete the frame.

I know there are a lot of ways to secure one bed on top of another to make bunk beds. I looked at several of them including cross braces between the legs, a system of pins between legs, etc. I finally settled on the brackets. It went with the rustic/farmhouse style that I like and it was also a little simpler for me to pull off.

One thing to remember is that this joint between the two beds is THE MOST CRITICAL ONE OF THE BUILD. You want to be extra certain that the way these are mounted together is secure and durable. The last thing you want is to have the top bunk slip off the supports from the lower bunk and come crashing down! So whatever you do, make sure you put in time to think it out and have it tested or validated so you know it will make a strong, reliable joint.

I went with brackets to hold the two bunks together. The brackets are 16 guage L braces (7 inches long)similar to these here: https://www.fastoolnow.com/l70.html?productid=l70&...

I purchased 8 of these brackets and screwed them to the legs using 8 #10 3/4" screws per bracket. The brackets were placed in opposing corners from each other. I attached them to the bottom bunk first and then slid the legs for the top bunk in to place and screwed them in.

The frame of the top bunk continues much the same as the bottom bunk with the exception of being able to assemble the pieces separately and then lift them into place. You still use the same brackets in the corners of the frames, you still attach the plywood scrap pieces to the inside of the frame to support the plywood, and you still need to reinforce the corners... though there is a little change with that last part.

Before, I had braces made from 2x4's connecting the 2x4 frame pieces to the 4x4 legs. That is not necessary here. Those braces were put in to prevent the legs of the bottom bed from spreading apart ("doing the splits") when carrying the load of the top bunk. Since the top bunk legs are rigidly attached to the bottom legs (via the brackets spoken of in the previous step) they can't spread apart it the bottom ones can't. If, however, this top bunk were to ever be separated and used individually then it would need braces at that time between the frame and legs.

Another change here is that when you attach the 2x2 corner braces (between the 2x4's) they should be in-line with the ledges the plywood will sit on. This is a detail that could be incorporated in the bottom bunk but is more critical here. By placing the corner braces on the same line with the ledges the plywood can set on them as well. Increasing the support on the plywood minimizes the risk of it slipping out of place. Also, making the plywood a snug fit in the frame will add to that security as well.

Once again the basic idea is the same here as with the bottom bunk. The plywood is still cut to 74" x 43" to fit snugly in the frame. The difference here is that instead of cutting off the corners of the plywood as was previously done, only a square is cut from each corner to make room for each leg of the bed. Cutting a 2.5" square will leave some extra wiggle-room to help the plywood fit around the leg.

As a side note, this will be the way to cut the plywood on the middle bunk as well. The reason the bottom bunk was cut differently was because, as I was testing the assembly process, I realized that it wouldn't work without modifying the plywood. I saw that, once fully assembled, the plywood for the bottom bunk could not be removed. The legs of the middle bunk got in the way of the plywood and prevented it from coming out without the extra space to maneuver.

As this was a design/development process for me I took things apart and re-assembled them several times. Because of that I got to look at several different assembly procedures. Here are my thoughts on how the bed should be built/assembled:

1) Cut wood and sand/finish the pieces

2) Assemble the bottom bunk

3) Assemble the legs and long sides of the top bunk and prep the short sides for later install

4) Assemble one long side and short side of the middle bunk (making an "L" shape using 3 of the bunk's legs) and prep the other two sides for later install

5) Move the bottom bunk into location (where the bed will be used)

6) Attach brackets to bottom bunk legs (for attaching the top and bottom bunks)

7) Lift the two long pieces of top bunk frame into place, slide into brackets and screw the legs in to place

8) Attach the short ends of the top bunk and finish assembling the top bunk frame

9) Move the prepped pieces of the middle bed frame into position (remove the stand-in piece of the "pass-through") and connect in to the brackets there

10) Finish assembling the middle bunk frame

11) Attach guards to top and middle bunks

12) Attach ladder to upper bunk

12) Place plywood pieces into top bunk, bottom bunk, and middle bunk (in that order)

You are nearly there! You just need to build and install the middle bunk. The cut list specific to this part of the build is:

4x4:

45" (x3)

2x4:

71" (x1)

39" (x3)

28.5" (x1)

~50" for corner braces

2x2:

~36" for corner braces

4x8 plywood (.75" thick) - x1 -- cut to 73.5" x 42.75"

.75" x 1.5" (taken from plywood cut scraps)

61" (x1)

29" (x3)

22" (x1)

To start this part of the build, pre-assemble one long side and one short side of the frame (71" and 39" respectively) to the legs. You should have an L-shape with the 3 legs attached.

Mark on each leg the height of the top of the 2x4 frame. That is 15 inches from the top of each leg. Attach the 2x4's as before with the brackets you've been using so far.

The stand-in pass-through needs to be removed from the lower bunk to make room for the leg of the middle bunk. Move the pre-assembled section of the middle frame into place and screw the leg into the pass-through space in the bottom bunk.

Once the middle bunk section has been moved into place you can complete the assembly of the frame. Use the 39" and 28.5" pieces of the frame to make the other long side of the frame and the final 39" piece to close out the final side of the frame. The trick here is that you'll need to work around the legs of the upper and lower bunk. The middle bunk frame has to link up with two legs that are part of other bunks. With these legs, mark the height up from the ground to where the top of the frame will be (instead of the typical measurement from the top of the leg). The measurement should be 30 inches.

As has been done so far, reinforce the corners with 2x2 braces (between the 2x4's) and 2x4 braces (between the legs and 2x4 frame). The reinforcement done on the corners is the same as done previously in that:

1) the 2x2 braces are in-line with the ledges on the frame interior (like the top bunk)

2) the 2x4 braces are included (as was done on the bottom bunk). The slight change in the reinforcements this time is that the 2x4 braces are placed below the bed frame (rather than above)

At this point the beds are mostly finished. However, they still need the safety feature of a guard rail on the top and middle bunks.

Up till now, the cut list has called out 5 inch wide strips to be cut from the plywood pieces being used with the beds. These strips will become the guard-rails. The guard-rails will go around each of the open faces of the elevated beds and be held in with the brackets being used thus far with the frame. Where you set them may vary according to your needs. I set them all so the top of the the guard was 3 inches below the top of each bunk's legs...that seemed to work well for my kids.

Finally, you need a way to access the top bunk.

I cut a 2x4 to match the space between the top and bottom bunks (~44 inches) and then 3 rungs from 2x4's (~ 18 inches)

The rungs are screwed into the 4x4 leg and the 2x4 cut for the ladder. Once attached via rungs, the 44" 2x4 is connected to the top and bottom frames via some scrap wood pieces I had in my garage. The idea is to just have another connection point on that side of the ladder to stabilize it while climbing.

The spacing of the rungs will vary according to your needs. I had my kids test them out so I could ensure they were placed so they could be usable.

That's it! You've got the bed assembled and it's ready to be used. It was a big build so pat yourself on the back!

My kids are loving the bed and enjoy being able to have their own sleeping space. It's great to see it all come together how it did! If you have any questions please let me know and I will do my best to help answer them and direct you in the build.

Enjoy!