The infrared image below was taken by John Snell of The Snell Group. The structure had recently been insulated with blown in cellulose. What is wrong with this picture, and what's the solution? What steps should the contractor and installation crew have taken to avoid this?
It is best to list the conditions when the image was taken and the palette used- I will assume winter time with a heated interior because of the warm areas around the windows and the 38.5 degree tag:
This appears to be balloon framing - note the lack of a band area showing between the upper and lower row of windows.
It also appears that there are fireblocks in the wall - specifically for one problem, there is a row of fireblocks between the two upper left windows. If this is the case, the insulator did a ridiculously poor job - he did not fill the cavity above the fireblock and he did not fill the cavity below the fireblock. Look to the immediate right of the right upper window - there appears to be a cup full of insulation in the upper of the two cavities. Look at he right of the upper left window - missed virtually all of the cavities there.
If he were trained in proper densepack techniques he would have a better chance of getting good fill. And using a scanner after insulating (temperature and time permitting) is the perfect training tool for a couple of dozen jobs.
To correct the situation now, put a Post-It note on the wall at the center of every defect you want repaired, then have someone do the repairs that knows how to insulate.
Congratulations to Bo Jespersen of The Breathable Home in Manchester, Maine who clearly knows his way around blown in cellulose, and maybe chicken coops too! We received many great responses to last month's stumper, but Bo sent us the most accurate diagnosis and complete solution.
Says Bo: "This picture shows the kind of situation that keeps me up at night. I own an insulation company and this type of installation is what we would deem unacceptable in anything other than a chicken coop! What we have here is cellulose installed in a wall that has both settled, and in some areas, been missed altogether."
Bo explains that the installer used the drill-and-fill method by drilling a small hole (or two) in each stud cavity, inserting a small nozzle, and blowing the cellulose directly against the finished wall. "The problem with this method is you can never be sure of the density of the finished product, or that full coverage isn't being prevented by a block or obstruction."
This technique has been used for many years, and until the advent of IR cameras, was assumed to be sufficient. The picture however, is what we see more often than not with this technique, whether in a home that was insulated last week or 30 years ago.
The solution lies in first installing the insulation correctly, and then verifying that it completely filled the cavity. Says Bo, "We have found that the best way to install cellulose is to drill a larger hole in each stud bay (3"), insert a fill tube that reaches both the top and bottom plate, and use an insulation machine that is calibrated to 3.5 lbs. per cubic foot. Finally, before any holes are plugged, we inspect each bay for complete coverage via an IR camera. The density of the cellulose assures it will not settle like it did in the picture, and the IR camera makes sure that all areas are filled."
Bo adds that all is not lost for the property owner. "The building can most likely be re-insulated with dense pack cellulose if they use the above technique - we have to do it all the time!"