At the end of my recent blog on Kooltherm rigid phenolic foam insulation, I mentioned that the roof and wall assemblies at an energy retrofit project in Brattleboro, Vermont, were insulated with cellulose by a company called . The company claimed that the German blowing equipment they use delivers cellulose at a more consistent density, and they were willing to prove it by doing a demonstration installation at their shop in Hadley, Massachusetts.
American Installations uses equipment to install cellulose insulation. X-Floc is a manufacturer of insulation blowing equipment with headquarters in Renningen, Germany. The equipment manufacturer calls their approach the “X-Floc ventilated dry injection system.”
The X-Floc head (see the photo at above right) has a perforated collar connected to a cloth bag so that the air pressure driving the cellulose injection is relieved. (See Image #2, below.)
Wes Couture, one of three brothers who runs American Installations, describes their use of the X-Floc injection system: “The built-in passive ventilation for the cavity gives you the ability to handle the air that is being expelled from the cavity, and it provides a more uniform product.”
Couture continued, “The system is dustless. With a standard hose, there is no control to that air release and the air is basically being forced out the same hole that the hose is going into along with the cellulose; it is much more difficult to ensure consistent density on every cavity with this strategy. This system brings us to a single installation of the air barrier and dense pack [insulation] through the air barrier, and the cellulose is then also in direct contact with the air barrier as well. And because the air relief is built into the nozzle, we can install product significantly faster in certain situations, as we are able to increase the airflow much higher than if we were using a hose in a cavity with no air relief.”
American Installations prepared two demonstration set-ups in their shop. The first was a three-cavity wall with a plexiglass face pinned in place with 1×3 strapping at each stud (see Image #3, below). The second test was of a small wall mockup that PreCraft built for the energy retrofit project in Brattleboro. This mockup included rough framing and board sheathing with clapboards, so we could see how the cellulose filled in the gaps expected at this type of assembly (see Images #4 and #5).
The video clip below is of the second (middle) cavity being filled with the X-Floc injection system.
The next video clip (below) is of the third (left-hand) cavity being filled using a conventional hose system.
The video clip below shows the left-hand cavity (insulated with conventional equipment) being teased apart to show the “plug” that the hose leaves at the tail end of the installation, with inconsistent density fill.
Image #6 (below) was taken at the end of the left-hand (conventional) fill. It shows the gap left by the hose at the end of the installation.
Images #7 and #8 show how the X-Floc dry injection system allows insulation fines to fill small cracks and crannies. American Installations claims that the X-Floc equipment results in better airtightness but admits that they have not — and to their knowledge no one else has — measured an increase in airtightness.
The video clip below shows two of the four short cavities being filled with the X-Floc injection system in the mockup wall framed with rough lumber.
Image #9 (below) shows the cellulose fill in the mockup wall after taking off the interior rigid insulation.
Image #10 shows the mockup with a cavity unpacked, revealing the extent and nature of the fines and fibers filling the cracks and crannies.
The demonstrations show how the X-Floc dry injection system achieves a uniform cavity fill with cellulose. Does the way the insulation fines fill cracks mean that the wall insulated with this installation system achieves significantly greater airtightness? I think the answer to that question depends on the results of future air leakage testing. Stay tuned.
In addition to acting as GBA’s technical director, Peter Yost is the Vice President for Technical Services at in Brattleboro, Vermont. He has been building, researching, teaching, writing, and consulting on high-performance homes for more than twenty years. An experienced trainer and consultant, he’s been recognized as NAHB Educator of the Year. Do you have a building science puzzle? . You can also to get a free report on insulation, as well as regular posts from Peter.