Dense-packed insulation
GBA Editor
| Posted in Green Building Techniques on
Hi,
I’ve worked with blown cellulose a few times, in attics and such. Each time I rented a blower from a big-box store. However there seems to be no provision for dense packing with these machines. Where do you find /rent dense pack machines and find good usage directions? Thanks.
Scott
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A quality machine and proper technique are requisites for a quality job. The Force 3 is perhaps the best portable blower on the market, though any machine with two 3-stage blowers would probably be fine. Hunt around at rental yards and lumberyards (some lumberyards will offer a machine rent-free if you buy their cellulose). A blower should be able to provide 80" water column (2.9 psi) air pressure at the outlet. You can test a machine by dense-packing a box of known volume and weighing it before and after to determine whether the minimum 3 pcf density has been reached. Do this test with the maximum length of hose and at the maximum head (height differential) that will be required for your job.
The Force 3: http://www.inteccorp.com/Force3.htm
For basic instructions: http://bct.nrc.umass.edu/index.php/publications/by-title/cellulose-insulation-a-smart-choice/
http://thenauhaus.com/blog/index.php/2009/06/how-to-make-sure-cellulose-insulation-is-dense-packed/
I recently rented an Intec Force 1 from an equipment rental place, and it does seem to have dense-packing ability due to the fact that it has an airlock (rotating vanes) that keeps air from bleeding out through the material hopper. They claim it gets 3 psi, and it did have some fairly high pressures while I was using it. I don't think it has the material feed rate that a more powerful machine would have, but it can get a fairly high static pressure in the cavity, and the density seemed pretty good. I was doing some irregular areas so I don't have exact lbs/cu ft. figures, but it used a lot of material compared to my estimates.
You have to rig your own hose though.