2- panels of OC703 insulation
2- 8' 1x4's for each trap, cut into two 4', and two 2' sections.
-8 1.5" screws -enough fabric to cover your frames
-some staples to keep the fabric on,
- 2 screw hooks for mounting to the wall.
We will begin by building a frame out of the 2 foot & 4 Foot sections, held together buy two screws in each corner. We then continue the assembly by laying our frame over a section of our fabric, and after pulling the fabric tight, begin stapling to the frame. Any breathable fabric works well on this project. For this example, I used some heavy sheets that I found at goodwill for $2 each.
Next, we insert our rigid fiberglass insulation panels into our partially covered frame. I used Owens Corning 703 panels, 2"thick. There is a comparable Johns-Manville product, or Roxul rockwool is also adequate. You will need to find an insulation supplier near your town, as this stuff is not at all like the fluffy pink stuff generally available at big box hardware stores.
My frames were a little short of 4 feet, so I trimmed off the excess insulation with a serrated knife I also picked up from the thrift store. I do not recommend cutting these panels with a knife you plan on using in the kitchen again.
We continue to cover the backside of the trap with our fabric, remembering to pull tight, fold in our corners neatly, and then staple. After our cover is in place, I trim off the excess material, and set it aside for later use.
I chose to attach 2 screw hooks to the back side of the trap, and mount two eye hooks in our wall to mount the panels With our eyes and hooks in place, we simply lift and hook the panel in place, straddling the corner of our room at a 45 degree angle.
Some of us have doors in the corners of our rooms, so in the pic below I decided to hang this corner panel with some chain from the ceiling, allowing the panel to move in the event someone needs to open the door.
Don't forget about wall to ceiling corners as well. Low frequencies build up in all corners, not just the 4 vertical corners.