Wood framing guys, how can I do this safely?

[hoosierdoc]

i've been bitten by the aquaponics bug. This means I need more grow bed area. I want to make what this guy did in his video but it doesn't seem strong enough.

https://m.youtube.com/watch?v=jRfUQtKc0fM

i basically need an elevated trough. I'll frame the trough with plywood and lay a pond liner in it. I just need a safe way to elevate a 4x8' bed about 30" off the ground.

Can I just put six 4x4s in the ground to make the basic shape and screw a ledger board to it then add joists to this? I need vertical support 12" above the bottom support to hold the walls up. Just not convinced strapping headers to the side of a post will be strong enough. If it can be... let me know how

this will be about 32 square feet and have about half a cubic yard of water and a full cubic yard of haydite. I'm estimating total weight of around 2000lbs, or 62 psf. With only a 4' span I was going to use 2x6 16" OC but very nervous about the support of headers.

in the video the guy just used 2x4 for everything but had two for posts.

 

[Ballistix]

Look at deck building diagrams. Lags and notches would be plenty of support with 4x4s. Stringers 16" on center using straps. I would use 2x8s.

 

[hoosierdoc]

Can I notch and keep going up on the post though? It's the extension to hold sides in that is confusing me. Also, would it be a single header rather than double? That would make it easier still and I guess if notched tightly the wood would all compress together

 

[billyboyr6]

I would build just As he did only with 2x6's vs the 2x4's. Couple years ago i built small deck to set hot tub on and used treated 2x6's. Hot tub weighs 400 lbs roughly dry and holds 275 gal and 5 people and has never moved. I'd say you'll be just fine.

 

[Ballistix]

The weight is the concern. The lateral force should be minimal. It looks like it would be approx. 16" deep inside? Sorry, I didn't watch the full video. If the x and y are notched at the base of the box and at the header of the box and lagged or carriage bolted, it will be very strong. 6x6s could be used for the supports if that would make you feel better about the strength, but it's a little over-kill. I would also add gussets to help with racking. It's hard to explain through text, but I could draw a diagram.

 

[Rookie]

Buy the steel and I'll weld a bed for you.

 

[Rookie]

If you don't like that idea, use King studs and Jack studs.

 

[hoosierdoc]

I like the king/jack stud idea, thanks. I'll tie them together down into concrete and then add the joist at the top of the jack, and the king holds the sidewalls up.

 

[HoughMade]

I'm starting to believe you need to work more.

 

[Tactically Fat]

I'm starting to believe you need to work more.

His wife picks up the slack.

 

[hoosierdoc]

I'm starting to believe you need to work more.

i practice in the highest burnout field and went into afib twice in 11 months. I'm comfortable with my work load

 

[HoughMade]

His wife picks up the slack.

Too much time around the house....but maybe this says more about my marriage than anything.

 

[seedubs1]

Just look up deck calculations on google. You can plug in a weight and it'll tell you the options for the joists to meet code (cross section and CTC spacing). Super easy.

 

[hoosierdoc]

I can do a flat deck, it's the top support that has me confused. Essentially a lot of people leaning on a Railing all the way around

i think rookie's idea will work

 

[Ballistix]

It's your structure, so it's your decision. However, jack studs are to carry overhead loads and transfer the load down to the foundation. They aren't for lateral stresses. By attaching two 2x4's together, there is a weak point created with a lateral load. By using notches, you would support the forces in both directions and it's much stronger.

Using the notches and carriage bolts or lags around the top header, the load is distributed evenly around the perimeter. Look at the simple design of an above ground pool. It uses vertical ribs and a top rail that is joined together at each rib. It is built using sheet metal and is a bit larger than what you will be building. Your concern isn't with the sides being forced outward, but the weight to be supported.

 

[HoughMade]

i practice in the highest burnout field and went into afib twice in 11 months. I'm comfortable with my work load

Yeah, well I'll give you that.

 

[Ballistix]

This isn't to scale, it's just to give you the visual. It's just a quick and crude drawing.
A cap or top rail can be added for aesthetics and/or to cover the attachment of the liner.

 

[Rookie]

That's why I suggested steel first.

 

[hoosierdoc]

That's why I suggested steel first.

$$$$

is that a 6x6 post in drawing?

 

[Rookie]

Probably $60.