[j10c3y25]

So my girlfriend has been getting into gardening lately, and I wanted to do something nice for her (plus I get to build stuff). I came across the square foot gardening method of using raised boxes, and that's where it started. "Honey, I will build you a garden box," couldn't possibly be that simple for me, so in my usual WAY over the top style I had to amp it up about fourteen notches.

Here you see some [very] rough sketches of the box concept, along with my materials list, both of which ended up changing along the way. Dimensions are 2'W x 6'L x 34"H, so you can reach the entire span of the box from one side, as well as stand comfortably without leaning while you work. The box will be self watering, in the sense that there will be an internal water reservoir that will only need periodic filling, and the soil will only pull up what water it needs through the wicking process. The base of the box stands at 14" off the ground, and the internal box depth is 16 3/4" after subtracting the thickness of the frame and bed. This gives me room for my layers as follows: The box will first be sanded and treated with linseed oil to protect it, then I will install landscape fabric or burlap to protect the plastic from sharp edges, a layer of 6mil plastic to make the inside water proof, another layer of fabric, the PVC pipe system, a 4" layer of gravel as my wicking medium, another layer of fabric, 10-12" layer of soil mix, and then mulch on top. I will also be adding some trim and decorative pieces to the top, and incorporating a level indicator into the watering tube. I got lots of good information from this website http://www.resilience.org/stories/2011-05-31/bottom-diy-guide-wicking-beds

Some quick math told me I would need 8 cubic feet of gravel, which will displace ~60% of the water layer, giving me somewhere in the neighborhood of a 13 gallon reservoir. Using conservative estimates of weight per cubic foot of soil, water, and gravel, the total weight of my full box would be close to 1500 pounds. This means every square foot of box space must support 125 pounds since I was determined to make it elevated. Not only that, but it would need to withstand the outward pressure of a half ton of wet soil. GAME ON. If there is anything I'm good at, its over-engineering the hell out of stuff. I set my bar at being able to jump around inside the box with the intent of breaking it and it not budging an inch.

This is the completed bed support frame, the cornerstone of the whole box and my first real attempt at using any sort of joinery (if you want to count lap joints). It is constructed of 2"x3" studs, cut to 6' and 2' lengths, and lap joints every foot on center. The two outer most laps are on the opposite side, allowing the outside pieces to be flipped over. In this manner, even dry fit I can pick up the frame from any piece as it is completely interlocked. I wanted to finish the project with NO fasteners showing, so I predrilled holes along the inside of the bed frame to attach to the sides. Then I glued the laps together and placed a sheet of 3/4" plywood sheathing on top, drilling screws down and through the center of every lap joint.

The sides are just butt jointed together with 3" wood screws, and at this point are not attached to each other at all. Each level is just its own floating rectangle until the legs are attached.

Underside of the box, here you see the frame is hidden by being flush with the bottom side rail.

Here I have assembled all four layers of side rails and installed the legs. The legs are just 2'x4' butted and screwed to 2'x6' boards, but I used an oak dowel to make plugs and hide all the screw heads. I predrilled holes from the inside to attach all the legs, and fastened with 2.5" "high performance exterior screws". They had a 5lb box on clearance for $9, and they are far superior to the wood screws I was using as proven by a quick test. I screwed half of each kind of screw into a scrap 2"x3" and hit them sideways with a hammer. The SPAX construction screw snapped on the second light tap, whereas the exterior screw I was able to bend all the way over and then all the way back up before it snapped.

I put the box on the ground and romped around in it with all 200 lbs of myself and its solid as a rock...BUT!--I am not satisfied. As it stands, the sides can still be considered not attached to each other, all the downward pressure on the bottom frame is supported entirely by the screws from the bottom side rails into the legs. In order to remedy this I need to install some bracing vertically on the sides that is not in contact with the ground, then the load can be spread onto the rest of the fasteners on all the side rails into the legs, thus adding tremendously to the strength. I've got some leftover 2'x4' which I plan on cutting 20" lengths and putting at 2' and 4' on center on each side. After that I need to figure out what kind of molding and corner squares I want to use.

Hoping to get to the braces in the next couple days, then have it sanded and finished with linseed oil by this weekend. I haven't even started on the PVC system yet, I gotta drill a sh$$load of holes -_-

This may be more of a gardening project than a woodworking project, but I am building it with wood so I think it counts! I do wish I knew more about construction, I'm fairly certain I have used 100% more materials than necessary, and that you could most likely set a tank on this. But hey, all part of the fun I guess.

More to come...

 

[Geoguy]

I like it. Nice and sturdy. The hard part will be moving it out to the patio when finished.

 

[johnnie52]

It looks really nice, but how are you planning to make it hold water and how much water are you planning on?

 

[j10c3y25]

It looks really nice, but how are you planning to make it hold water and how much water are you planning on?

That would be the layer of 6mil plastic I mentioned that will line the inside. With my gravel layer at 4" I should have somewhere around 10-15 gallon water capacity in the reservoir.


So anyways, I drew a couple sketches to see which way I liked better, a single piece in the center or two pieces at 2' intervals, and definitely liked this better.

Here you can see I have made good use of my 5 lb. box of screws.

The only thing left to do before finishing is some of the decorative pieces to hide these corners.

I'm thinking of trying to fashion some kind of pyramids or the like from all the scrap I have left to use at each corner, and also the centers where the brace meets at the top. I just don't know if I should leave it at that or put some kind of trim on the side rails as well, I can't imagine anything that looks right for some reason.

 

[Pauley]

Very interesting...I'm looking forward to seeing more.

 

[eepaul]

A 6mil plastic liner will very likely leak, especially with that much weight and the rocks in the reservoir. You dont need to get a really heavy duty 45mil liner, but hd and lowes sell ones that are less heavy duty and should work. The one linked should fit your box. Also, unless you plan on putting the rocks in very slowly one by one, you might tear (almost guaranteed to tear a 6 mil linear) your liner when pouring them in. I have pond in my apartment that is similar in construction to your box, and used a sheet of insulating foam as padding for the sides and bottom. You shouldnt need to pad the sides of yours, but I would recommend something more sturdy than just cloth as a liner.
http://www.homedepot.com/p/Total-Po...ft-Pond-Liner-PVC12005/202278976?N=5yc1vZbx70
http://www.homedepot.com/p/Unbrande...ft-Foam-Insulating-Sheathing-754404/100572981

 

[frankp]

A couple of comments... don't line your box with fabric, even if you use a heavier liner for water. The liner WILL leak at some point and then you've got wet fabric rotting against your wood. Also, linseed oil will only protect the wood for maybe a month or two outside.

If I were building it, I'd use a sealant on the wood, either some marine epoxy or at the very minimum a spar varnish. I would also use a pond liner,which will be closer to 20 mil thick, generally. I wouldn't bother with "cushioning" the sides with any kind of soft liner, be it cloth or foam just because both are going to pull water from your system when the liner leaks. I'd also make sure I could move the thing easily, though now that you've built it full size that's going to be significantly more difficult.

Also, I can't tell for sure but it looks like the hardware you used isn't likely to last submersion for very long. Something else to consider.

 

[johnnie52]

I know we are taking your hard work apart, but better it comes from us than from a bunch of water on the floor.

Its a good design, you just need to rethink how you're going to keep the water in it.

 

[frankp]

Johnnie makes a good point. I should have also included that I really like the design and aesthetic of the thing. We've been bouncing back and forth about whether or not to build some raised gardens at our house. A design like this might really be a good compromise.

Your construction method is going to be plenty sturdy, too, which is always good for things that are going to hold as much weight as it seems like you're planning.

 

[eepaul]

I certainly didnt look at it like taking your work apart, and hope my post wasnt construed that way. I have just built several ponds of my own, (Ill get around to posting my current one someday) and can almost guarantee that a 6mil liner will tear. The purpose of the foam on the bottom is to give the liner some leeway when you pour the rocks in. If you pour them in and the liner is just sitting on hard wood, again, it is almost guaranteed to tear. Even if the wood is smooth, the liner has pressure on both sides from hard surfaces. If you get a super heavy duty liner (45mil+) you dont necessarily need the foam, but those are pretty expensive and I think getting a cheap pond liner and a foam sheet is just as efficient of an option.

 

[j10c3y25]

Thank you guys for the comments, I have to admit at first I was a little peeved, but you made some valid points. I did need to rethink a few components.

I tested some sheets of 6mil plastic by dropping and stomping gravel into them, it made marks for sure, but no tears. Nonetheless, it would be near impossible to repair if torn, and I don't want to go buy expensive pond liner, so I found a solution. Multiple layers of plastic (its cheap and I have a big roll) alternating with layers of landscape fabric (like they make bullet proof glass). 4x6mil=24mil, works for me.

I found many instances of raised beds that are built with cedar or redwood and left unfinished, unlined, and can last for years (10-15 in some cases), which is why I chose redwood. I'm aware that it won't last forever, and I'm ok with it. I am, however, going to change to a food safe finish of food grade mineral oil/beeswax, because apparently boiled linseed oil contains some additives I don't want anywhere near my vegetables. It'll look nice for a while...and then it won't, we'll see if I'm not too lazy to apply a new coat to the outside when we get there If you know of any food safe finish that will last longer let me know, but as I imagine, nothing will be very permanent and safe at the same time.

I don't understand how landscape fabric would rot. Its a synthetic, basically made of plastics As far as I understand its much more susceptible to UV damage than water damage.

No one is submerging any hardware, and even if I wanted to it says guaranteed against rust for LIFE right on the box, certified by Rustoleum! Hey, its gotta count for something right?

I'm going to try my damnedest to get it done this weekend, between my physics lab report and trying to wrap my brain around this materials science class. Crystals! Everything is Crystals! It's terrible -_-

 

[j10c3y25]

I abandoned the post cap idea when I saw something I liked much better. Here is a dry fit of some of the pieces

Its just a 1"x10" pine board that was very symmetrical looking in grain pattern, so by sawing it straight down the middle and staggering the small pieces, it looks like it matches all the way around, even though only 2 corners truly match. It was going REALLY well until on one of the miter cuts my radial saw bound up and a fist size chunk of my corner snapped off. Its ungodly frustrating, I had to stop and build a straight rip jig for my circular saw earlier because I have no jointer, and then after tediously dimensioning everything perfectly this happens. I've rigged this up in an attempt to pull it back together, after it dries I'm going to try to put a spline in the bottom between the two pieces for a little extra strength.

 

[eepaul]

Hey another physics student! What physics lab are you taking?

 

[johnnie52]

I like how your planning to do the top. :thumbsup:

Looking at how you are trying to fix the broken corner I noticed what looked like a large knot right at the angle. Pine is really weak at the knots and miter saws are not very delicate. I'm glad you didn't get hurt when the saw tore the corner and that you have developed a way to fix it. :thumbsup:.

 

[frankp]

I like the top edge, it really finished it all. In reference to your cloth comment/question about rotting, I didn't see that you meant landscaping tarp. That wouldn't be too much of an issue and shouldn't soak up too much water either. That said, I don't see what you gain by using it other than expenses. It's not really going to protect anything or add any padding, though putting on the top layer to prevent weeds would be a good idea.

The redwood will look like it should if you don't bother with any finish or minimal finish. Again, the mineral oil and beeswax really aren't going to do much except cost you money. At most they will only last a month or two. If that's your plan, I'd just leave it natural with no finish at all and save your money. Like you said, it will look nice for a while and then it won't. (Although, I personally like the look of weathered redwood for outside furniture etc so I think it will still look good. Besides, it's a garden it people will (and should) be looking at the plants, not the container.)

I really enjoyed my materials science class, way back when. Where else do you get to build things and then break them just to see how strong they are?

 

[j10c3y25]

I got a lot done!

Here you seen the broken corner piece, the glue up worked so that was good.

I made these miter clamp jigs from a diy article on the internet somewhere, and then I used a chisel and some cut off strips to make splines to hold the joints together. My miters weren't perfect, partly because of the broken corner, and also I believe partly due to an issue with my fence which I haven't fixed yet, but no biggie. I filled in the gaps with some shavings/strips, and sanded everything flush, overall I'm satisfied with it.

I also put together the fill piping

There are about 100 holes drilled along the tubes near the bottom to allow even water distribution, and the piping increases the reservoir capacity by displacing some of the gravel.

I sanded the box itself, then put my glued face frame on top and screwed it down. Used the same oak dowel to fill in all the screw holes, then sanded everything flush and finished the whole project with butcher block conditioner. The bottle actually stretched pretty far, managed to get 3 coats out of it. Everything turned out great!

All that's left is to put in the drain pipe, level gauge, and line the insides, and I can get it filled up and ready to plant.

 

[Priusjames]

It's looking good...I've enjoyed watching the build, thanks for sharing!

 

[ssgtjoenunez]

This came out great! My wife has been looking to get into gardening and I had thought about doing above ground planters but nothing this nice (or tall!).

She really wants to do some light vegetables and maybe some chiles. Either way I might be stealing some (or all) of this thread

Nice work! I am really interested in the plumbing and how it all turns out.

 

[frankp]

Agreed, the final solution looks quite nice. Good job.

 

[ssgtjoenunez]

I was curious if you had thought about pre-drilling pockets holes in that top 2x10 so that the top frame could have been attached without the need to drill, dowel and fill. I've been thinking about making this for my wife and was thinking if I created pocket holes on the top 2x10's (before they are screwed together to make the frame) then I could avoid having to dowel and fill.

Also - any update on the plumbing inside the box? I am curious how you are going to check the level.

Thanks!