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Building Science

Installing Insulation With the X-Floc Ventilated Dry Injection System

A Massachusetts company claims, “We don't just do cellulose; we do it better.”

X-Floc, the company that developed this injection head for cellulose insulation, claims that the blowing equipment provides more consistent insulation density than other cellulose blowing systems. The head has a perforated collar connected to a cloth filtering bag.
Image Credit: Image #1 and Images #3 - #10: Peter Yost
View Gallery 10 images
X-Floc, the company that developed this injection head for cellulose insulation, claims that the blowing equipment provides more consistent insulation density than other cellulose blowing systems. The head has a perforated collar connected to a cloth filtering bag.
Image Credit: Image #1 and Images #3 - #10: Peter Yost
According to X-Floc, the air pressure driving the cellulose injection is relieved by the collar and the filter bag.
Image Credit: Image #2: X-Floc
This photo shows the exterior side of the three-cavity demonstration wall. The Plexiglass face is pinned in place with 1x3 strapping at each stud. This photo shows the interior side of the mockup wall framed with rough lumber. A photo of the exterior side of the mockup wall framed with rough lumber. This photo was taken after the left-hand stud bay was filled with cellulose using conventional blowing equipment. The photo shows the gap left by the hose after the installation was complete. This photo shows a stud bay insulated with the X-Floc equipment. It's possible to see signs that cellulose fines filled the small cracks and crannies. Here's another photo showing how the X-Floc equipment allowed the fines to fill small cracks and crannies. This photo image shows the cellulose in the mockup wall (the wall framed with rough lumber) after the interior rigid insulation was removed. This photo shows the mockup wall (the wall framed with rough lumber) after the cellulose was "unpacked."

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 American Installations. 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 X-Floc 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 BuildingGreen 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? Contact Pete here. You can also sign up for BuildingGreen’s email newsletter to get a free report on insulation, as well as regular posts from Peter.


  1. bencarsan | | #1

    Interesting but I have lots of questions
    The crudeness of American dense pack equipment is obvious and has probably frustrated installers like me for a long time. We make do with repurposed hose from other industries, poorly formed transitions between hose diameters, hose clamps for connections, big heavy loud machines that throw dust everywhere and aren't very portable even with wheels etc. And there's no pressure dump as on this German unit, so might have to wait 20 seconds after blowers stop in order to pull the hose out. Improved equipment would improve the process, but I am actually pretty satisfied with the outcome we get on inferior equipment.

    This demonstration leaves me with lots of questions. The videos don't look like the kind of dense packing I do. My understanding is that you only get reliable density a short distance from the tip of the hose, say 12-18" with a 1-1/4" and less with larger hoses which deliver a lower pressure/material ratio. So the process of dense packing typically involves a lot of "retubing"--pulling the hose out a short distance and then pushing it back in so that it you find and fill pockets of lower density material. When you get to proper density, the machine stops pushing material, and you move the hose until material starts flowing again. The X-Floc appears to have a nozzle not designed for attachment to a hose and it appears to be filling an entire cavity with no hose, but to what density? And the "conventional" video doesn't show any retubing, so I would expect uneven density there.

    Furthermore there may actually be a benefit to not having a pressure dump in retrofit situations, since the pressure will tend to drive material to leakage points in a stud bay, similar to the way that a product like "fix-a-flat" finds and fills a hole in a car tire.

    I look forward to learning more. Any idea about the price of the X-Floc equipment?

  2. GBA Editor
    Martin Holladay | | #2

    Response to Bennett Sandler
    Thanks for your comments. I haven't blown as much cellulose as you have, but I had a similar reaction to the demonstration. Clearly, if the company performing the demonstration wants to prove the superiority of the X-Floc equipment, they have no incentive to do a good job when using the "conventional" equipment (which is being used only to prove the superiority of X-Floc).

    I don't think the kind of voids shown in the video are typical of the work of an experienced dense-pack installer.

  3. user-6811621 | | #3

    looks similar to Krendl KD1
    which is manufactured in the USA, so likely cheaper in North America. No experience with either to know if there is a performance difference.

  4. GBA Editor
    Martin Holladay | | #4

    Response to Brian Croston
    You're right -- the design of the X-Floc head certainly resembles the design of the Krendl head (shown in the photo below).

    Krendl is an American company with headquarters in Delphos, Ohio.


  5. Matt Z | | #5

    x-floc nozzle
    My comments would parrot Bennets'. The idea of a pressure relief is appealing as we are asked to Dense-Pack behind smart membranes all the time and I hate doing it. We seem to have to go back and re pack after the cavities have had time to de-pressurize, and we seem to have to put a lot of holes in very expensive membranes. A bit counter-intuitive. We prefer the netting and aluminum tube method as was once professed by Sir Hulstrunk.(maybe still is) Yes it's dusty, but at least we can see what we are doing and visually verify that everything has been covered. Has anybody checked the density after using the single point nozzle?

  6. user-6811621 | | #6

    @ Matt
    If you watch on of 475's older Intello Plus dense pack YouTube video, it shows Hulstrunk recommending cutting a slit in the membrane to relieve air pressure and provide an airpath for cellulose to travel. In a wall with continuous stud cavities, it would require many slits, but should be easy to seal with good tapes.

  7. user-4739854 | | #7

    It's Beautiflul... but Where's The Beef?
    With the olympics out of the way, let's not judge cellulose like figureskating: we need to quantify the density with measurement of weight over volume. It looks nice with "consistent density", but what is the density? The suspense is killing me.

    The unit comes with a beefy coreing tool and a two-decimal place digital weight scale stored in Euro-chic tool box (see picture) and there's a nifty density chart (see pic below) on the body of the machine to boot. It would have benefited us all to see the installers demonstrate per German-style simplified pictographic instructions:

    Couldn't help notice that the plexiglass - not a whimpy flexible sheet good stapled to the stud - was flexing like Lou Ferrigno - still alot of pressure back there even with a vent.

  8. JasonMTodd | | #8

    expensive valve with options, but its fluid dynamics after all
    I appreciate the videos and article. I've been looking at the x-floc (its not cheap) and while I think it could prove useful with membranes in particular its a specialty tool not a panacea. It certianly works in PH construction using plywood as air barriers. Consistent large cavity installs with a rigid clampable surface for the rotary valve. The x-floc looks good here. They seem to have quite the variety of options including valves with tubes for probing.

    Pressure relief behind membranes makes sense too, (but we loose the clamping option) as Hulstrunk demonstrated with 475 as referenced, they don't vent well on their own when installing.

    The best part of these valves may be dust maintenance if they seal well to the wall.

    The "traditional" tubing demonstrated was as mentioned, not ideal for sure I believe better results can occur. In the end its air flow or fluid dynamics. if the rotary valve is 3" to 2.5" and the wall tube is 3" down in stages to 1.5" the rotary valve will fill much faster.

    Use the largest wall tube that will fit, set machines to dense pack verifying with a density box, do it properly and i'm not sure the rotary method wins.

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