Blowing Cellulose – Dust?
Getting ready to blow a bunch of cellulose in the attic, some across an open ceiling, some dense packed into the rafter bays. Before making the big buy and getting the blower I bought a couple bundles to hand pack the insulation into some of the hard to get areas. While doing this I noticed I needed my respirator because of the dust coming out when I broke up the clumps. Do I need to plan for a dust cloud when I blow the cellulose?
Yes. but It can be controlled/reduced to some extent by adjusting the air gate inlet. Don't adjust it too low as it will load the blower motor and you'll not get the coverage/ Rvalue as designed.
when the insulator blew mine, he add small amount of water to the mix to control dust.
Never did that with cellulose. Would take quite a bit of water to keep cellulose dust down. That might add enough weight to cause more settling than is normal with a non-compacted open attic blow.....10-15% , and then total R will be reduced. Used to add small amounts of water to fiberglass to keep static electricity at bay. If you didn't do that the stuff would stick to the rafters, truss struts and you'd lose coverage as well as getting serious static shocks from the hose. The static shocks occasionaly happen with cellulose. (maybe that was what the water was for)
(haven't blown glass since 1983; lost my biggest customer for a couple of years but he switched to cellulose and was interested in cellulose in new walls just before I moved here in 92. He never got to try the cellulose walls as he stopped being a contractor. Lucky guy- met and moved in with a rich specialist doctor- built a large (????) energy efficient house for them. He now raises horses and organic grains/ foods/veggies for them all!!!)
Yes, you do. It's worth buying a Tyvek suit, as well. I have found that I rather enjoy the tangy flavor of the borates, however.
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None of this matters in geological time.
Like drywall, it's part of the deal.
You get a lot of free trash bags though.
My cellulose guy stuffed the empty bags (from his last jobs) with some fiberglass, and put them into the rafter bays on top of the exterior wall plates and below the vent chutes. Keeps the cells from falling into the soffits.
Sounds clever, but I'm thinking you have a big cold spot right there now.
That bag of FG isn't providing much insulation value at the spot that has the least room for insulation.
If this wasn't a retrofit, I'd have had a heel wall put there to get more insulation r-value over the plates. As it is, I did feel with my hand during winter ... I did not perceive much difference in temp. That doesn't mean there isn't a heat loss there at all, but I can tell you I do not get icicles or snow melt in those areas.
Edited 10/29/2005 9:37 am ET by PatchogPhil
Never had to blow loose fill insulation myself (or by myself). Isn't it pretty much a 2 person job? Is it even possible to do with one? I guess if you had the blower up in the attic with you...
Cellulose blower machine rigs have an on/off switch on the business end of the hose. You "could" do it alone but you'd have to keep going back to the machine to fill it up with the next bag. This is really a 2-man operation.
You could do walls by yourself as it's a slower process due to drilling/checking walls, you blow with more air/less cellulose for packing and might only get 10-11 bags into the walls on a real good day. When I do the odd house for friends/aquaintenances now, I usually do the walls by myself during the week days and do the attic with thier help on Sat or Sun.
i have been meaning to start a thread for this, but this one seems like a nice one to hijack. can someone explain the difference between dense pack and loose fill? i had a house done with wet cellulouse, by spraying it in the stud bays before hanging the drywall. now, i have an old house with t&G inside and out, and i need to blow it in the walls before i replace the badly done drywall. any hints on how to would be appreciated.btw, it has been my experiance that the hopper loader gets more on him than the guy inside, but both get pretty dusty
The densepack method of blowing is used to get more airsealing out of the cellulose. With the product I use now (ground by a "fiberiser" process like stone ground flour) we get more R value out of less cellulose. The regularly installed density for attics is 1.6-1.8 lbs per cu ft and for walls, to prevent settling, is 2.8 lbs/cu ft.
I've measured 2 rwo stroey houses with a blower door before and after blowing walls at regular densities to determine air leakage reductions. The results were 34 & 39% reductions just by blowing walls. In some of the weatherization programs in the US, the cellulose is blown up to approx 4 lbs density (hence "densepack") to further increase the airsealing effect. I've never done that as people didn't want to pay for the extra material and were going to do their own airsealing using regular techniques.
the guys who blew mine. one was in the attic with the off/on cord. the other would load the hopper with a water hose in hand. after each load he mist the hopper, no dust, no mold, it work
is dense pack something i can do myself, using products and rental blower from the big box store? if so, where would one go to get instructions? thanks.
You can approach densepack with the smaller rental/loaner blowers by drilling extra holes in the cavities. The densepack is usuaully done with larger gas/diesel 20+ hp engines. It takes a skiled operator to install densepack with these units as you can actually bow or blow out wallboard/plaster.
With the smaller blower with 120 volt motors, you can't won't get the high end of densities but you can still effect some decent air leakage control. Normally on an 2" X 4" X 8' cavity with no braces or other cross framing, two holes are needed to to get proper density just to prevent settling- one about 2.5 -3.5' high and the other within 1-2' of the top of the cavity. When you run into corner bracing, you will need a third hole in some cavities (those with the lowest and highest parts of the diagaonal brace) as you don't want holes more than 4-5' apart for good packing.
To try dense pack with a small blower, you would need 3 holes in each cavity- 1.5' from bottom and top and the third at the 4' mark. You would have the air gate gate near full open to get greater velocity/pressure to pack the material. Some blowers may give you a decent increase in density; smaller ones will not. After blowing a couple of bags, you can do a quick calculation based on wall framing taking up about 15% of the gross wall area. If it doesn't seem to be getting much over 3 lbs /cu ft, then just go on blowing for anti-settling densities with the 2 hole method.
we blow about 3.7 with typical 3-holes, an old ( 1980 ) US Fiber machine and a Hurricane blowerMike Smith Rhode Island : Design / Build / Repair / Restore
We must be brothers-in-arms. I'm using a Heat Seal machine I've had since 1980 also with a 22 amp Dumore blower. Rebuilt the electrics (coils, commutator) of the blower 2 years ago and it cost me more than I paid for it!!!
Can the rafter bays of a hip roofed vaulted ceiling be dense packed? My family room addition has t/g paneling in the ceiling attached directly to the 8" rafters.
yeah, you can do it... but your paneling might look like wavy-gravy when you get doneMike Smith Rhode Island : Design / Build / Repair / Restore
Even with 3/4in pine?
i missed the t&g, yes , that will restrain the cells enough to get dens-pak..
what are you going to do , take out a board top , bottom & middle ?
or bore holes thru your paneling ?Mike Smith Rhode Island : Design / Build / Repair / Restore
I was thinking of getting into the long runs through an adjoining attic. On the short runs (on the hip roof) I thought of going through the soffit on the outside. Anticipate any problems?
no problems , just a long day..
how long are the "long runs"
i usually tape a 4' piece of pvc with a reducer to the end of our hose..
it may be hard to maneuver if you have to go around a corner to get into the bay
trying to "push" the hose is a problem with out a straight pipe sectionMike Smith Rhode Island : Design / Build / Repair / Restore
The longest bays are about 14ft. The total area is about 325 sq ft. With 8" joists, I'm figuring total volume of 244 cu ft. How much material will I need?
depends on how tite you pack it... 3 # / cf @ 244 cf = 732 lb.
26.5 lb / bale = 27 bales.....say $7 - $8 / bale
most times it comes in pallets of 31 bales , so figure a pallet
now .. if you can get it really packed, say 4 lb.... well,do the math
also , i don't know what your supply channels are..
if you can get it , ask for the 100% Borate..it's a superior product to the Aluminum sulphate treated material..
sounds like funMike Smith Rhode Island : Design / Build / Repair / Restore
Yes, they can. You may have to work from the eave and remove the soffit so as to be able to slip the hose or hose with rigid pipe up the slope. Don't know the length of the longest rafters or if there is any open flat attic in the higher reaches of the vailted ceiling or is it fully vaulted.
You can also get into the cavities by lifting shingles and drilling down into the slopes. This has to be done with care especially if the shingles are old and brittle. It may be best to do the insulation when you replace the shingles (soon I hope)