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I am getting ready to rebuild my raised beds. Old beds were 4x4's in the corners with 2x10's on the sides. Pretty basic! I'm taking a little bit different track on the new ones. I'm planning on stacking 4x4's something like this....

4x4_Raised_Bed.JPG

My beds will be 4'x8' and 4'x12'. I am planning on going up 6 layers for a full height of 21". Corners will be overlapped. Each side will be a single piece (except at the overlapped corners).

Questions:

1) Would it be better to use screws or nails/spikes to tie the levels together?

2) Would it be a good idea or a bad idea to also use construction adhesive to really tie it together. Kind of concerned about this as I'm thinking that the timbers will want to expand/contract independently. But I think they should be "connected" in some manner for the overall structural integrity.


NOTES:

I am using 4x4's instead of 6x6's due to the overall cost. I have a total of 6 beds and using 6x6's would add right at $900 to the overall cost of this project. I can buy a lot of veggies for $900!

I am using treated lumber for the beds. Although the newer treating techniques claim it's safe for food gardens, I'm still not crazy about it. BUT, I am also putting a 35 mil thick food grade plastic liner between the soil and the lumber to isolate my growing medium from the treated lumber.

Using cedar instead of treated would add around $450 (assuming 4x4's).

I am going 6 layers / 21" tall to accommodate Sweetie. Due to some medical conditions, it's getting harder and harder for her to get up and down. And I ain't getting any younger myself. I kicked around 18" vs. 21" tall and opted for the higher bed. Once I build 5 layers, I'll take a look at it and make a final decision.



Any thoughts on screws/nails and also about using adhesive would be appreciated. :good2:
 

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I built mine using 10" long screws. Stack the 4x4's 3-high and run a screw through in each corner and every 4' down the sides. That way if a board starts to rot I can disassemble, replace and re-assemble without major hassle. Construction adhesive just seems excessive to me.

I originally built mine with cedar 4 years ago. I'm rebuilding them this year using PT. The cedar boards rotted with the moisture trapped between the boards and the plastic liner I had used.
 

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Questions:

1) Would it be better to use screws or nails/spikes to tie the levels together?

2) Would it be a good idea or a bad idea to also use construction adhesive to really tie it together. Kind of concerned about this as I'm thinking that the timbers will want to expand/contract independently. But I think they should be "connected" in some manner for the overall structural integrity.

I am going 6 layers / 21" tall to accommodate Sweetie. Due to some medical conditions, it's getting harder and harder for her to get up and down. And I ain't getting any younger myself. I kicked around 18" vs. 21" tall and opted for the higher bed. Once I build 5 layers, I'll take a look at it and make a final decision.
Any thoughts on screws/nails and also about using adhesive would be appreciated. :good2:
I like the idea of tall sides. :thumbup1gif:Wish ours were taller.
I'd go to Home Depot and buy 24" x 1/2" rebar, drill through and hammer them in. 3/8" rebar would work also.
Being removable is always a concern of mine.
 

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Discussion Starter #4
THANKS for the replies, Jim and Keith!! :bigthumb:

I like the idea of the rebar but the idea of drilling enough holes through 21" of PT lumber on 7 beds doesn't thrill me! :laugh: As per Jim's suggestion, I picked up some 10" screws. I'm going to tie layers 1, 2 and 3 together with a set of screws. Then I'll put layers 4 and 5 on and connect them into layer 3. Then, if I decide to go to layer 6 (21" vs. 17.5"), I'll use 6" screws to tie layer 6 into layer 5. I'm going to use 6" screws to tie the corner ends together.

I went to Menards yesterday and picked up the majority of the lumber. Pretty much bought out their stock of "Cedartone" pressure treated. I'm going to start the construction tomorrow and will only use the better lumber. Taking most of the stock meant that I had to take some that I might not like. I'm going to use the "best material" first and then I might go to another Menards that has a pretty good amount of stock and cherry pick their stuff. Then take the not so good stuff back. Kind of a pain, but these beds are going in a pretty visible part of the yard and I want them to look good as well as be functional.
 

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I also vote screws or lag bolts. Gizmo2's way would be cheaper, but more work and not disassembly friendly.

With a raised bed, do you fill it completely with top soil? Or 1/2 full with gravel/stones???
 

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4F2717A0-2EE3-45D8-8106-B4D656439A67.jpg

We used 1x6 cedar decking boards screwed together with steel corners, going on 8 years still going strong.
I will at some point have to redo them, but think I have at least another 7 years to go.
Put 3/8” square wire mesh stapled to frame on bottom to keep critters from tunneling into them. Also allows roots to grow through if needed, have made them anywhere from 11 to 22” tall
 

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Discussion Starter #7
With a raised bed, do you fill it completely with top soil? Or 1/2 full with gravel/stones???
I don't know what people that actually know what they're doing do, but my plan is to put some "hardware cloth" with 1/2" holes on the bottom. Then I'm going to but in some "filler" of small logs, branches, hay or straw in the bottom of the bed. Then I'll top that off with compost to the top. There's something called "Huglekultur" that I'm going to mimic in the beds. A lot of people have had good luck with this approach. The decaying material in the bottom of the bed provides nutrients and also helps to keep the soil moist.

These beds are pretty much an ongoing experiment for me. I didn't grow up gardening with my parents and up until we moved out here, neither of the houses I owned were conducive to gardening. Even out here it's tough as most of the property is wooded so finding a decent space on the property that gets enough sun is kind of tough.

Part of my experimenting this year is going to be using wood chips (from my chipper) as mulch to keep the weeds down. Again, I've done a lot of reading on this. A lot of people will say to not put wood chips down in the garden as they'll steal the nitrogen as part of the decay process. But, other studies have found that the chips only use the nitrogen where they touch the surface of the soil. So they're not denying the root structure any of the nutrients or nitrogen that they need. If you till the chips into the garden, that's a different story. As the wood chips decay, they return nutrients to the soil and you end up with nice stuff. I don know that where I spread chips between my beds, the soil underneath is gorgeous!!

Like I said, it's all an experiment! It helps to keep me out of trouble. :laugh:
 

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On the 12 foot beds, have you given any thought to tying the long sides together about 2 or 3 courses from the top? May not be needed, but I tend to over-build, and doing this would prevent any possible bowing out of the longer sides.
 

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Discussion Starter #9 (Edited)
I've thought about it, but going to try and avoid it. I'm hoping with 4x4 sides (instead of 2x4's) that I'll have enough strength that I won't need to tie them together.

When I built my first few 4x8 beds, I put a piece in the middle to tie the 2x10 sides together. It was a major pain and in the way when I tried to till the beds. Want to avoid that if possible. Of course, these new beds will be twice as tall (21" as opposed to 19") so I'm hoping the extra height doesn't necessitate tying the sides together on the longer beds. I'm thinking that if I did need to tie them together, it would be required more at the bottom rather than the top - just due to the "down pressure" at the bottom of the bed from the dirt up top.

Of course, I'm hoping that I can condition the new beds to the point where they're no-till anyway.

I will be posting pics when I'm done with these so everyone can critique them.
 

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I would definitely recommend screws for fasteners.

I made my wife's raised bed as a deer proof garden with a door. I used 4x4s for posts and 2x10s for the boxes. The 4x4s in the middle have one 4x4 going between them for stability.

 

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I would definitely recommend screws for fasteners.

I made my wife's raised bed as a deer proof garden with a door. I used 4x4s for posts and 2x10s for the boxes. The 4x4s in the middle have one 4x4 going between them for stability.

Very nice-looking set-up! I built six 4’ x 12' (in 2 rows of three) raised beds of PT 4x4’s. I. too, had to accommodate a grade over the length of each bed. My minimum depth is three 4x4’s (at the high side of the grade). The bottom of each bed is lined with 3/8” hardware cloth. Each row was screwed to the row below it with 6” screws. I tied the corners together with 6” screws. I installed a 1” pvc pipe, flush with the top row every three feet around the perimeter. I can then insert a smaller OD (can’t remember the size) pvc pipe and bend it across the width of the bed. Draping mesh over the smaller pipe creates a “tunnel” and keeps the local creatures out of the bed. Sorry I don’t have pictures, I’m at the office perusing my favorite website. Mine are about 5 or 6 years old, made of PT lumber and are holding up well (and no one has grown a sixth finger or anything). I originally filled them with a "raised bed" mix blended by the local supply company. Every other year I add a couple of bags of raised bed mix from Lowe's or Home Depot. The boss, well, she's quite happy with them.
 
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