That sounds about right to me. When we did our baloon frame house this fall we started with the recommended 18" -24" above the sill and below the eve and then roughly 1 more hole for every 8 feet, so 3 holes per cavity. Once we got the hang of it we found we could drop it down to 2 holes and still achive the same ammount of fill in the wall (based on material in and time to fill).

The risk you take with a hole in the middle of the wall of a baloon frame is filling the ceiling of your first floor w/o noticing it (or so I am told).

If the contrator has been around for a while and had reputable references I think your fine. We did our house ourself but have already noticed a huge payback this winter.

YMMV...

They need to be dense-packing this insulation or it will eventually settle.

If cellulose is simply blown into place, as it is blown it gets fluffed up and has a low density. Over time it will eventually settle and become more dense. This is why when blowing cellulose into an open attic, if you want 12" of insulation, you blow in more so that it will settle to 12".

"Dense packing" means that the insulation is blown in to achieve an installed density of about 3.5 poinds of insulation per cubic foot. Since this density is higher than it's natural settling densty, the cellulose will not eventually settle in your wall cavities.

Dense-packing knits the fibers together. You get a great air barrier, great sound deadening capabilities, and with the exception of foam, one of the higher R-values out there.

Best way to tell if they're dense packing is to do a bag count as the insulation is being blown in. Calculate the rough volume of a stud bay and see how many stud bays are being filled per bag used. Use stud bay volume divided by bag weigh to see if you're getting the required 3.5 lb/ft^3 density.

If they are not dense-packing, they are not doing the job correctly, as it's guaranteed to settle and result in cold spots at the tops of your walls.

If you don't mind telling me, I'd love to know how much it costs to get something like that done professionally. I realize that it's going to vary by size of house and region, but I don't even have a basic ballpark idea about this type of work. Thanks!

Great follow-up mongoct. I did forget to mention that we calculated how many bags we needed based on the desired r-value and broke that down on a per cavity basis. That way we knew the right ammount was going in the wall each time.

Oops.

Regarding my earlier post, to make sure that you're getting 3.5 lb/ft^3 density, divide the WEIGHT of the insulation blown into each bay by the VOLUME of the bay. POUNDS per CUBIC FOOT.

In my previous post I wrote it backwards.

Mongo

Wish I knew how many bags they used.... I do know it consistently took 120 seconds to fill a two story bay.

The cost was about $1.45 SF, and the blower door test was $55. They removed and replaced wooden siding around the house as needed, placed foam plugs in the 2" holes they made and replaced the siding with galvanized nails. Installation went rather quickly with a team of three.

They are scheduled to finish in two weeks...

Can this sort of thing be done from the inside of a house (if you don't mind me changing the subject a little bit)? I'd rather have holes in my interior than the exterior since I don't have siding (and the interior needs some plaster work anyway).

We have a stone house and had cellulose blown in about 23 years ago. Yes, it can be done from the inside.