Infra-red wall inspections reliable at over 40deg? — Heating Help: The Wall
Infra-red wall inspections reliable at over 40deg?
I had forgotten about that, in mild weather on the sunny side in particular a heat soak works against you sometimes. I witnessed a test once and we soaked the building at 80 plus degrees to "force leaks". The technology is pretty amazing. I am sure the current cameras are much more advanced than what I have been involved with. I can imagine digital enhancements can compensate for a lot of variables. Yes, do post the results!
Having my walls scanned tomorrow morning to check for gaps
in insulation. Temperature's likely to be low 40s. Company told me it works as long as it's at least six degrees colder outside than inside.
Anyone verify this? Seems the test would be less conclusive, especially if, at 9am as this is planned, some sunlight is shining on the outer clapboards building up radiant heat.
Also I wonder if someone really skilled can infer an R-rating from an infra-red photo scan based on the degree of darkness/lightness.
Depends on the resolution of the equipment
Some of those set-ups are pretty accurate and can detect fractions of a degree. The higher the cost, the more accurate. And the more they must charge to recoup their investment. Some of those go into the tens of thousands of dollars.
As you suspect, the greater the temperature difference the greater the contrast. You may even have to fire up your heating system to limit in advance of the test to allow a heat soak to increase contrast. Makes for sharper images.
Thanks Brad, though the tech tells me too much heat in this warm
weather may cause less contrast due to the heat permeating all the areas that might show up as cold if it was twenty degrees colder. Don't know. I had cellulose blown in recently if that factors in. Too bad it's not february, but hopefully I'll get a good reading. Part of it will be interpolating what I'm seeing; maybe i'll put a few photos on the wall afterwards and see what you guys think.
It's useful since I'll also learn exactly where the risers are, maybe firestop locations, etc.
Infra-red insulation photo results
Showed that most areas were well-filled with the cellulose. Also revealed the diagnol wall bracing. Seemed to work despite the above 40 deg. temps (65 inside).
photo #14: shows infiltration into ceiling. might be worth looking into, or perhaps it's from a cold spot in the window header.
photo #17: show risers, above window header cold. Also cold corner very tough to insulate. Note how on left--and through all the pictures I have--studs are conducting cold. Guess that's why on new construction they try to stagger different sets of studs.
#19: the one area --to left of door--that the contractor missed, probably due to the altered framing years ago when they took out windows and put in a door. He could have gotten it by opening new entry point from below. Same thing happened to the right of door.
Note that this will not read behind the left and right window framing where the cavities from the old windows with the chain and ballast are still empty. Can only reach this by removing window framing from inside.
Tech recommended that if possible band joists between 1st and 2nd floor--which are usually open to the sheathing for a height of about 6"--to be caulked, then sealed/insulated. That would be a bit of a job.
Overall, very worthwhile, informative, and cheaper if you don't need a big written report afterwards. I just pay him for his time and he emails me the photos an hour later.
i read that night is a good time to take readings...
some cameras can take a picture of a large building and pickup the heat from electrical wires that are drawing heavy amps...or take pictures of one square mm of a printed circuit board and pinpoint highest heat and lowest put a point of reference on the pic and a scale in 6 seperate band widths and colours....
Yes, if you took night photos of all four sides of your house
you would get an idea of overall heat loss areas. They say a photo of the main electrical panel can pinpoint electrical failures before they occur.
The tech told me that while a blower door test can show you where the infiltration is exiting and quantify the heat loss in terms of hourly changes of air, the infra-red can show you where the source is--which might be a different location due to chimney effect, etc. Also detects source of moisture problems. Also they can photo the same infiltration location from both inside and outside; the former would show cold infiltration, the latter would show the warmth escaping.
Seems like it might be a good idea to do both blower door and infra-red at the same time; then you should do another test after sealing and insulating. So of course then it's costing you maybe two years to earn back in fuel savings what you spend on the analysis, but oh well no pain no gain.
David. That may be the precise number..
then again the fact that you will then also have controlled ventilation better insulation and perhaps a real vapor barrier coupled with the correction that would have diverted health issues ....one might be investing in some far better returns than immediately apparent on first perusal *~/:)
Yes I totally agree plus the whole process fascinates me
The cellulose insulation, infra-red etc were preparatory to repainting my 1924 clapboard balloon-framed colonial. Only thing left is to know whether I should be somehow venting the clapboard walls to let moisture out. Some painters use shims to keep the clapboards 'breathing' but that can invite insects. The only vapor barrier I have is the old tar paper (maybe the 4" blown-in cellulose as well?), sheathing and plaster/lath. (Wherever they opened a clapboard to drill a row of holes for the cellulose they removed the tar paper, which i guess shouldn't matter for such a small area.)
I have yet no controlled ventilation system; roof is unvented but no problems after 80 yrs, except that as house gets tighter I should get some kind of system, especially if I seal the attic and make it an enclosed space as in building science unvented attic.
Jonathan_9 Member Posts: 1
insulating band joists
I used to hire thermographers to check wall insulation jobs for a low-income weatherization program. Yes, turning on a blower door (at low speed) while the infrared camera is running can be informative. Surfaces that looked OK before the blower door was turned on get mottled with cold spots if the insulation isn't dense enough to stop air movement, or there are air leakage paths bypassing the insulation.
Some insulators who use the "dense pack" method to install cellulose say they can drill through the band joist and blow a "plug" of cellulose into each joist cavity. Gives an air seal and insulates at the same time. Where porches connect to the house is often badly sealed/insulated, and this method fixes it.
Regarding adding shims to ventilate the siding: If you have problems with paint flaking, it's seldom vapor diffusion from inside that's the problem, especially if you keep your winter indoor relative humidity under 40%. Air leaks carrying warm moist air, and vapor drive from outside when the sun hits siding after a rain are more common problems. Good priming on dry wood when repainting can help. I suggest paying attention to when the problem occurs and consult w/ somebody experienced if the problem happens. Incidentally, insects don't like cellulose, as it's treated w/ borates. One mfr. even advertised the anti-roach virtues of cellulose insulation.
Glad to see your thermographer shot from the inside (preferred method).
Yes, because my 1st floor ceiling was partially open in one area
I was able to glimpse the band joist between 1st and 2nd floor. (I had thought band joists were only at basement level.) As you probably know usually the cellulose crew will open up two clapboards--one near the bottom the other about 10 feet up--to drill holes through the sheathing every 16" or so. If they find an obstruction they then take off another clapboard in between the other two they've removed. They will be able to reach the band joist area from above or below; but in my case looking from the inside, I found it completely open into the house --meaning after the clapboard and sheathing--so any cellulose there would not really have anything to seal tightly up against. Though a good pile of it near the edge is certainly better than nothing.
Your post has given me the idea that if they opened up a clapboard at the particular point that the band joist is--and I've been speaking of the sides that the joists are parallel to the clapboards--their two inch hole could allow them to blow directly into it, though still there's no backing. Perhaps some polyicinine blown in there would be best, same with the sides where the joists are parallel with the clapboards. I would think it a bit difficult to do this from the inside, though possible. The advice I've heard on this--doing it from the inside--is either to caulk, affix cut-to-fit insulation board then insulation against the sheathing, or just polyicinine expandable foam. This is true for the basement and probably the band joist just below the roof.
Another thought this gave me was that for anyone adding 3/4" polystyrene panel insulation, then vinyl siding to their homes over clapboards some nails might penetrate the styrofoam plugs used to fill the unseeable 2-inch entry holes for the cellulose, which might compromise your insulation.
As for insects, not that they'd like the cellulose, but that they like any sheltered area to nest in between clapboards. We found a number of wasp nests behind the window shutters when we removed them for the job. Probably more of a problem with vinyl siding since they're so loosely installed. Our painter suggested not using shims on the clapboard but also not to caulk the seams shut which might impede 'breathing.'
I've also been told re: peeling--amazing how many opinions there are--that cedar wood expands and contracts alot with the weather, so they recommend an oil primer, and of course, as you suggest, good surface preparation. Sounds like a nice dry October would be best to paint, but I won't have that luxury. By far the worst sides of the house as far as peeling goes are those with sun exposure.