Opinion on this crazy idea.

[John White]

I put up a second large building a couple of years ago, 50 x 80. I built it like Johnny Cash's car. One piece at a time as I got the money. Finally got a 500 gal plastic septic tank buried and run all my eves from roof into it for water. Now I am to the point to where I need to get some insulation in my bathroom so I can put a small heater and it will kick on for a few minutes when it gets below 32, to keep my water lines from freezing. When I built the building the posts are 6x6. Metal on outside and on a vapor barrier with osb board on inside. My idea was to have fiber glass insulation blown down between the walls at the top to fill the wall cavity. Which I still may do. But I have come up with a brain storm Idea. Bath room sits in corner. I insulated the two interior walls when I built the bathroom but the two exterior corner walls are not insulated. Here is my idea. I have access to damaged broken blue, pink and white foam board, free. My idea is that I have a old lawn mower on its last leg. I want to take the wheels off. Mount it solid on a 4x4 sheet of plywood, cut a slit about 2" wide and about 12" long across the front of the deck, get a large heavy duty bag, attach it to the chute then just brake the chunks of foam board and shove it through. I would fabricate a small chute about 2" x 12" so I don't get my hands near the blades. I asked a man I seen with a large comercial chipper and asked him about how big would the chips if he run a board of foam through it. He said probably about the size of a large marble. I could just buy a small home yard chipper, but it will only take about a 3"x 3" . I would just climb up on a ladder and pour this foam down the walls.

 

[J_J]

The suction will be from the bottom.

The lip on the blades is designed is to suck up and blow air/grass out.

I would block off the bottom except for a hole or slit.

Cut foam the length lf the slit and feed into the bottom.

 

[NorTracNY]

Not knowledgable here, but could the blade be safetly flipped to reverse the flow?

 

[Egon]

Not knowledgable here, but could the blade be safetly flipped to reverse the flow?

Good idea.

Do a test run before getting properly set up by just putting the lawn mower over some broken up pieces?

 

[paulharvey]

Hate to stop a crazy idea, but if its osb on the ezterior wall, can't you simply unscrew it, or pull the nails. Then place your syrofoam in the wall cavity, and rehang the OSB?

Or pull the exterior metal panels and work from the outside?

 

[deepNdirt]

I would certainly mock-up a wall cavity the size between the studs, Install a pc. of clear Plexiglas on one side, start filling just as you would the actual wall and take notice to see if the chunks of Styrofoam will drop all the way down and fill to the top,
What could be expected to happen is the pc's could gather up 1/2 way or only 3rd the way down and you would not get the wall filled,
The reason I say this is this was sort of my same idea in my converted living space of our attached garage, I would cut a 5" hole at the top against the ceiling and shoot insulation in each of the wall cavities, ....... I would come back later and install a large crown molding to cover the holes, I'm a Interior Trim contractor, and have many informed resources so I asked a Insulation man about blowing in the insulation for me verses cost of renting a machine and doing it myself, The first thing he said was it wouldn't work 100% ,

He said the insulation would not make it all the way to the bottom, Said that the forced air from the hose would fill the wall creating a back pressure and not allow the insulation to properly fill the void, Plus to add to the issue the insulation would hang up on the electrical wiring as well as any electrical Boxes within the walls and not make all the way to the bottom, The walls are 13 ft. high, his advice was to cutout a 5" strip of drywall about halfway up the wall ( roughly 6 ft. ) all the way around the room, fill from this point first, repair the drywall and rather than cutting holes at the top just for the blower hose, That I go ahead and cut out another 5" strip of drywall approx 3" from the ceiling,
The continuous drywall strip cut out provide enough airway for the air to escape from each void rather than to buildup air pressure in that void,

I realize the OP stated fill from the top and likely will have a contiguous strip cut out, and would probably work for the dropping it in method, My concern would be will the chunks hang up on things in the walls, and perhaps not make it down to the bottom,
I'm not clear on if the plastic barrier is against the outside of the wall or against the inside with the OSB? OSB has a smooth side and a none-slip side, depending which side is in the wall cavity could also effect the ability of the Styrofoam chunks to make it all the way down,
Although after OSB becomes so old and the glue starts turning loose, the shavings will start to lift making both sides rough enough for things to hang up on,

 

[LD1]

I would take the OSB off and put up 6" of fiberglass.

Even if you have to cut it out and buy new osb, for the size of the room, it would be a quick payback if you plan on using an electric or propane heater. You need to get them outside walls properly insulated.

 

[mikehaugen]

If you really want to try the blow-in approach, I think the chipper is a better idea than the lawn mower. You don't need 3x3 squares, but rather cut 3" strips. You could use a table saw to do it pretty efficiently.

But overall, I think removing the osb is is a better plan.

 

[mikehaugen]

Another thought about the blow in is if you can shove a hose all of the way down the wall and fill as you pull it out, it would insure that the stuff gets all of the way to the bottom.

 

[dave1949]

If you managed to get the chewed up foam in the wall, I wonder what the R-value is going to be? I can't even make a guess.

Foam insulation works because there is a lot of dead air space trapped in the material.