Heads up on Dense Pack Cellulose

[sdrobertson]

I wanted to give anyone using dense packed cellulose a heads up as I just check mine and I have quite a bit more settling that took place over last year than I thought I would. I stood 4 tanks on end in a square box. The area in the corners have settle about 3 feet but keep in mind that I'm insulating almost 16 ft from the bottom to above my rafters. I'll be refilling these pockets next week but it may be something anyone else might want to peek into there storage to see if they have any settling. It may be a case that I didn't pack it enough with the blower but I thought I had.

 

[DaveBP]

Cellulose blown in dry isn't the same as what is known in the trade as "dense-pack".
While you can blow in cellulose a little tighter than fluffy with the right use of the blower nozzle, real "dense-pack" is blown in with a special nozzle that dampens it and really packs it in. You can spray it overhead into cathedral ceilings and it doesn't fall out.
In my limited experience, dry blown cellulose settles 15% or more with time. The 'R' values on the cellulose bales allow for about that much settling. In a horizontal application like an attic, the 'R' values don't change much as it settles but a big void could be a problem in an outdoor storage tank installation.

I suppose if you were going to put in a depth of more than a few feet, tamping it as you go might help minimize settling.

 

[sdrobertson]

That makes sense...I blew it as dense as I could but I figure I probably had a few voids as it was hard to reach down 15' and try and control the nozzle. I'm glad I didn't try and place a cover over all the insulation as then I would have never really known and it's still a easy fix.

 

[pybyr]

True dense pack doesn't require wet-spray, although wet spray is one way to achieve it. The critical part is getting to the right density, and a good blower properly set up and operated can do it-- though it would indeed be hard to get the level of control if you're trying to reach 15 ft in. In this case, just keep adding and checking, and you'll be good.

 

[sdrobertson]

Quick Update....I took a shovel handle and started to poke into the insulation and found several more voids. They seem to be mostly around the walls and not directly by the tanks. I'm thinking I concentrated by the tanks more while I was blowing in the insulation and now I have placed another 70 cu ft of Styrofoam beads (we use them for block filler around these parts) on top of existing insulation and I'm back up to the line where I was when I first installed the insulation.

 

[DaveBP]

Check those beads sometime in the near future and report back, would you? I'm curious to see how they hold up to the heat.

 

[sdrobertson]

I did allot of research before I insulated...all the manufacturers would not recommend anything with prolonged temps over 170ish on the beads. I knew I was going to run around 190 so I went with cellulose. I put my hand down as far as I could reach in the insulation after I had the tanks charged to 195 and I figured that if I could take the heat on my hand, the beads should hold up. I did put about about 1 foot of the beads in the bottom and then filled the rest with the cellulose in case I ever got any moisture.