In this post I describe how I've built mine and connected it to my greywater irrigation system, although you don't have to have a greywater system for this project. I followed great instructions at www.abovegroundfarming.com for building one.
Here is the final result with some strawberries planted.
2x8 Pressure-Treated Hemlock Fir Brown Lumber
A box of 4 inch deck screws
Heavy duty plastic tarp
Organic Potting Mix (not Soil)
4 inch perforated drain tubing
4 foot Level
Step 1. Remove weeds and sharp object from the ground where your planter is going.
Step 2. Lay down weed guard to cover the area completely to prevent weeds from getting into the planter
Step 3. Build the bottom part of the planter frame using the 2x8 pressure treated lumber
Step 4. Lay down the plastic tarp to prevent water from the planer to leak out
Step 5. Cut the perforated drain pipe to the inside length of the planter and lay down the pipes leaving a gap in the middle
Step 6. Use one of the left over pipe pieces (at least 1 foot long) and cut out a small hole on one end of the pipe like this:
Step 7. Insert this pipe (standing up) at one end of a longer pipe inside your planter. This will be the place you do your watering. You can also use a PVC pipe cut diagonally for this.
Step 8. Build the same size and dimension frame using 2x8 pressure treated lumber and lay it on top of the bottom part built in step 3
Step 9. Cover the pipes with another layer of weed guard to prevent the potting mix from plugging up the pipes
Step 10. Poor some potting mix down the gap between the covered pipes and pack it in so that the pipes stay spread out. This is where your potting mix will soak up the water and bring it to your plants
Step 11. Fill up the planter with the potting mix packing it in as you go. You SIP is now ready to receive plants! I connected my planters to the greywater irrigation system and after a couple of load of laundry dug a hole in the potting mix to test the system. There was water at the opposite end of the planter from the watering point!
With strawberries and mulch
Step 12. Cut away the weed guard and the plastic that is still showing on the outside of the planter
For one of my planters I had to contend with a tankless water heater and a cat door. So I decided to make use of both. The condensate pipe from the water heater is now feeding my planter with about 3 gallons a day and the cats don't have to jump so high to get into the house, since they can use the custom walkway :).