How to figure amount of cellulose needed for dense pack wall?
 

Oh boy I'm showing my lack of math skills.
I'm having problems trying to nail down a quantity to nail down a price for blown in cellulose.

2X6 walls 2 ft on center 8 foot high.

If I'm figuring this correctly one cavity should be about 7.68 cubic feet?

From what I've read a dense pack target is 3.5 lbs per cubic feet?

So for one cavity it would take 26.88 lbs?

One net weight 18.10 lb bag is $5.99 and this isn't enough for one cavity?

Am I correct on this? I guess it seems like a lot but it is 2' on center.

I think I got it if someone could verify.

There are 55 cavities between the exterior studs.
Each cavity is approx 7.68 cubic feet
55 X 7.68-= 422.4 cubic feet total

For dense pack they suggest a target of 3.5lbs per cubic foot, so
3.5lbs X 422.4 Cubic Feet= 1478.4 lbs total
there are 18.1 lbs per bag so
1478.4 divided by 18.1 = 81.67 bags required. Round up to 82
82 X $5.99 per bag = $491.18

Seems like it should cost more.
Is this math correct?

Menards was selling their blown-in cellulose for $4 after mail in rebate until the end of September. I bought 50 bags at $4.29 each and got another 8 larger bags (21.4 pounds instead of the downsized 18.1) for $20. You can get just over 1000 pounds of cellulose, a bunch of spray foam cans, and the rental cost for about $300. Places like Home Depot and Lowe's sell it to you for more money but factor in the price of the blower rental to 20 bags, so if you get 20 bags it is a wash but for me blowing 58 bags it costs less to actually pay for the 24 hour rental at Home Depot for cellulose bought elsewhere.

Also keep in mind you'll probably get an even lower price if you buy this stuff from a lumberyard. Another member, I think it was S-F said that buying it from a lumberyard gets a higher quality product with lower dust. ..maybe bigger bags and a better price. Menards stacks 48 of the 18.1 pound bags to a pallet, when I bought mine, they just forklifted the pallet over and we loaded two vehicles with about 30 something bags, dropped off the cellulose at home, and came back for the rest of the load.

Definitely considering a lumber yard, but for initial calculations (after lumber yard hours) I can pull prices from the big box websites. Had a frown knowing construction isn't going to start until well after the rebate which usually happens around heating season.
There's a local tool rental that has a Force 2 blower that we'll rent to get the walls as dense as possible. Maybe use the free blower for the attic.
Also need to price the Insulweb at the yard too! Menurds is $468 for 8'X750' which is WAY more than we need.

In fact I still need to reprice the 12" energy heel trusses from a lumber yard rather than Menurds.
This new construction planning is so time consuming when you don't pick a floor plan and designer and all of that expensive route stuff.
DIY is more satisfying, cheaper and better quality in my opinion.

Especially when lots of homeowners don't get what they pay for with a general contractor anyway. Notice how the DIY and HGTV networks are moving into the kind of shows where the master expert comes in and fixes what jack leg general did wrong? They're called reality shows for a reason.

Not saying they are all bad: there are gobs of awesome contractors building and renovating our world. But Dr. Solar costs more (usually 1.5x more) than jack-leg Joe Solar Expresso. Doing your homework before and during the project can make a huge difference in its success. Especially when you pick the lowballer.

I just overbuy and make sure i can return return the excess. If it helps i think i went thru a bag and a half per 20"centers 10'high full measure 4" bay.

If its open bay, behind plastic, make sure to have thin plywood shields ready to screw up to control the bulge. Or you could learn the hard way like me