Cape Cod attic — cellulose machine
My finished attic in my cape cod has terrible temperature regulation up here in central Maine. So far I’ve put 1 inch foam between the floor joists sealed the gap with foam. I’ve also spent days air ceiling the upper attic. Next step is for me to dense pack the sloped ceiling, which is made up of 2×8 rafters. I’ll be using accuvent cathedral ceiling extensions to provide ventilation. The sloped ceiling is about 5.5 feet long so I’ll be connecting two of the vents together and stapling at either side. The house is about 34 feet long and I have slopes on either side. I plan to dense pack the sloped ceiling to the best of my ability and make upper attic around R 60 just in case the sloped ceiling settles, I’m hoping some cellulose from the upper attic will fall in to plug the gap if this happens. I’ve already bought 1000 + pound of all borate cellulose. Now I need to pick a machine to complete the job.
I know I’d get better results if I had a truck mounted blower, but I do not plan on hiring out this job. I have 3 options for a cellulose blower and I’m hoping for feedback. I can get the cacoon for 24 hours for free from the local home center. My local rental shop has an Intec Force 1 for $70 and an Intec Force 2: the next generation for $135. The force one is rated at 970 lbs per hour. The Force two is rated at 2,400 lbs per hour and requires 2-15 amp circuits and is rated to provide an air pressure of 4.5 PSI. Should I expect much different densities between these machines?
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Replies
Sci Fi Jock,
My only experience is with one of the Cocoon blowers that is lent out for free. But I don't have any doubt that you'll get better results from the Intec Force 2 blower, which is much more powerful, as long as (a) you know what you are doing, and (b) you don't overload your electrical circuits. It isn't unusual to have trouble with circuit breakers with these big blowers.
I imagine that you have already read the relevant articles here on GBA -- but in case you haven't, here are the links:
How to Install Cellulose Insulation
Borrowing a Cellulose Blower From a Big Box Store
-- Martin Holladay
You can dense-pack with a Force I as well, but it'll take a bit longer. It's a bit harder to have a blow-out with a Force-I than with the Force-II, which makes it a bit more forgiving for newbies.
Thank you for your responses. The article "How Install Cellulose Insulation" says to use a 2 inch hose to dense pack. Is this what I should use my ceilings? I have a direct line of acess to the sloped ceiling from the top attic and they are 8 inch joists that will be reduced to 7 inches becasue of the vent. Is there any reason to go down to 1.5 inches? Also, can I use PVC pipe reducers instead of buying the expensive dense pack kits? I'm thinking about using my 2 inch shop vac hose to slide down the cavity.
I'd also like to confirm that dense packing the sloped ceiling is preferable to just loose fill like a regular flat ceiling.
Dense packing with a 2" hose would require a Force-2, and even then you are almost certainly be better off with a 1-1/4" or 1-1/2" hose. At 1" or smaller it's more likely to get clogged or kinked, but 1-1/4" or 1-1/2" is fine.
A shop-vac hose is WAY too flexible- the tubing needs to be stiff enough to be able to push it through the lower-density cellulose without curling back around on you, and it needs to be able to reach the end of the rafter bay. Most box stores will have some collection of flexible clear plastic tubing of different wall thicknesses and stiffness. When in doubt, go for the fatter wall, stiffer flex. With only 5.5' of length to the dense packed bays it shouldn't be too tough working with a 5-6' dense packing tube. Going a bit longer is fine, but not shorter. (I have a stiff ten-footer in 1-1/2" tubing for longer framing bays, and a somewhat more flexible 6 footer in 1-1/4" tubing for working shorter bays & tight spaces. I'm sure the pros would have an even wider variety.)
The narrower hoses will be easier to insert through the lower density fluff, and cutting the tip at a 45 degree angle makes it easier still. There will still be times when running air-only on the blower may be necessary to get the tube all the way to the end of a cavity once the cavity has filled, but is not yet dense packed. The jet of air helps drill a path through the fluff while keeping the tube clear, and it stiffens the tube somewhat as compared to when there is no air flow for better directional control.
Cut the sleeve off an old sweatshirt and slip it over the end of the tube and hold it tight to the hole in the mesh (or wallboard, etc) to limit the amount of blow-back in your face while dense-packing.
Put a wrap of duct tape or some other durable mark around the tube about a foot from the business end so you know when the tube is nearly out of the hole, thus avoiding the "cellulose blizzard" effect.
Use a real respirator, not a cheap nuisance dust mask, or you'll have gray/black fire-retardent laden snot for days.
Yes, dense packing is WAY ahead of loose fill for sloped ceilings.
I am not going to bend it through drywall because I'll be in the top attic looking down each open rafter bay, so I don't need to have a very bendable tube. I was thinking about using the 2" rigid hose on my vac, not the flex hose. What is the stiff tubing called you said would be at the home center? I cannot find it on the home center's website. Could I use 1-1/2 inch pvc pipe and pvc fittings to reduce the pipe size? The metals ones specific to dense packing seem expensive for a one time use.
I'm hoping to rent the machine for just one day. I've got about 50 5.5 ft bays that need filling in addition to the 300 sq foot upper attic. Do you think both the force 1 and 2 are up to the task? Also, since the force II is more powerful, does that mean it is less likely to clog?
Martin / Dana - Are you still of the opinion that getting to around 3 lb./cu. ft. (minimum) will prevent settling in smaller cavities over time? (By small I mean not 24in o.c. double stud PH walls)? Does climate zone matter when talking about settling? I am referring to the linked article below for original info:
https://www.greenbuildingadvisor.com/blogs/dept/qa-spotlight/best-way-insulate-floor
In reading GBA and elsewhere (including Dana's helpful / encouraging comments above) It seems that first-time DIYers with a thoughtful approach and decent box store blower can get to 3.0 to 3.5 lb./cu. ft without a horror story. (I can also understand Martin's seemingly cautious approach to giving the greenlight to all DIYers in this regard.)
I am in a similar situation as Mr. Jock, but would be dense packing a smaller area (2x10 12in o.c. floor joists) which I am getting quotes for $3.50 / $4 a cu. ft. (With the small job and higher labor costs of Chicago contributing to higher price per cu. ft.)
Thanks in advance. (I also enjoy that GBA generally has real names attached to posts btw).
Regards,
Joe
Joe,
The usual target for most cavities is 3.5 pounds per cubic foot. I imagine that 3.0 pounds per cubic foot won't settle, but I'm not sure on that point. It would be best to aim for 3.5 pounds per cubic foot.
In a US zone 6 Central ME 3.5lbs would be advisable for wall cavities, but in sloped ceiling cavity 3lbs should be fine. Settling of celluolose is primarily a creepage issue related to seasonal moisture cycling, but the amount of weight and span between the rigid supporting structures count too: It takes higher density to avoid settling in a 12" double studwall to no than a 2x4 cavity due to the wider span (12" instead of 3.5") . But turned on it's side, dead-horizontal installations with between joists shouldn't settle even at 2.5lbs except perhaps in extreme moisture cycling conditions, since there is far less weight bearing down on it than with 8-10' of cellulose depth.
Even in a 12:12 pitched 2x8 rafter bay there isn't much weight to speak of either- 3lbs density should be fine.
Any idea about if the Force 1 and/or the Force 2 can get my project done with a one day rental? Is a more powerful machine like the Force 2 less likely to clog and cause me delays?
SciFiJock,
First of all, I'd like to urge you to update your user profile so that your real name is displayed. Here is a link to an article that explains the process: How the GBA Site Displays Readers’ Names.
Q. "Any idea about if the Force 1 and/or the Force 2 can get my project done with a one day rental? Is a more powerful machine like the Force 2 less likely to clog and cause me delays?"
A. It's impossible for any GBA reader to estimate how long your job will take -- there are too many variables. I imagine that either the Force 1 or Force 2 machine would work, but it's always necessary to have at least two people available for a job like yours. The person operating the blower has to check for clogs on the blower side, while the person in the attic has to pay attention to what's happening at the hose end.
In my experience, you'd want the force 2. Make sure the airlock seals are good--rental machines can get pretty beat and if the seals are shot you won't get density. Use either the food grade pvc tubing usually sold by ag places or if access is free and open you could use rigid--either aluminum or black poly pipe. Ordinary PVC will work but the static electric shocks are spectacular. Use a small diameter if you are using flex--1-1/4 is probably best. In rigid maybe 1-1/2. Normally the machine is calibrated so you know what density you are getting at a given hose length and hose diameter. There is some skill in all this. If you want to DIY, in order to get the density right you should go slow and plan to do a lot of "retubing"--pushing the tube back through material in order to add more until the machine "locks up" and can't push material and you can't push the hose back through. There are some Bill Hulstrunck training materials out there--videos and docs--that will be useful to you.
And FYI cape houses are widely known to be very difficult to air seal.
Bennett,
Thanks for your specific and helpful advice.
Using rigid tube for dense packing in a cramped knee-wall attic space is totally awkward. A 1-1/4" flex is the right way to go here.
Very helpful information - Thanks all.