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We are building a new home and recently had a pre-drywall inspection done by a qualified inspector. He came up with a couple of concerning findings and I was wondering if there are any experts in this forum who can help us.
a. Radiant Barrier - We chose the radiant barrier for our home thinking that it would definitely help with heating/cooling costs. Several people have also recommended on this forum that it is a good investment to increase comfort and reduce heating/cooling costs. However, the inspector said that there has been quite a few instances of houses catching fires in southern states due to the tendency of aluminium radiant barrier to attract lighting. Is anyone aware of this and do you think this is a concern considering we are building in Charlotte, NC area? Any advice here will be really appreciated. The inspector pointed us to this study - http://mcdowellowens.com/pdf/Unusual...-Causation.pdf
Now, I am trying to figure out if these housings are IC rated or not. The product specification says that these are IC and non-IC rated and I am not sure what that means?
I clicked some pictures of the housings. The labeling on the housings says that these are ICAT rated housings however, we also saw a sticker on one of the housings which said these should not be installed within 3 inches of insulation and that sticker should be removed in IC applications. I am confused that how the housing can be both IC and non IC rated at the same time depending on the installation. Can anyone please help here? I am trying to make sure these wouldn't cause any fire hazards.
I read with interest the article by the engineer in regards to an aluminum radiant barrier attracting lightning. I had these same concerns when it first came out. You'd be basically installing a lightning rod all over your roof....with one exception. There is no current path for the lightning to follow. Like anything with electricity, it has to follow a path to make a circuit. Electricians use this all of the time to work with live wires. Don't get into the circuit or become the circuit and it's harmless. With the radiant barrier, I know of no builder that grounds the roof decking. With out the ground, there is no circuit, therefore there is no attraction by lightning. I'd be more concerned about wiring just under the decking attracting lightning than the roof decking. The wiring makes a circuit, the decking doesn't. Same would hold true of a vent hood duct out of the top of the house, or a dryer vented thru the roof. These would be far more likely to attract lightning than a radiant barrier but they make no circuit and they are not grounded. I suppose if it really bothers you that a lightning rod could be installed but I see it as wasted money. Of the few houses I've inspected after a lightning strike, while damage to the decking was evident, it was not the source of the grounding. The lightning went thru the decking to a ground source in the attic. What the engineer might be missing in his assumptions is that the radiant barrier, in that circumstance, might heat up and catch fire. Of those I've seen, it was accompanied by rain which quickly extinguished any fire. The holes blown in the decking by lightning have been from baseball size to big enough for me to crawl thru. It's also been my experience that a house struck by lightning suffers from a lot more than any fire. Most springs in the house no longer work right- like window sash balances. Most any electrical appliance is either toast or will die a lot sooner than later. Cartridges and flush valves in toilets are done or will be soon as are any faucets. It's really a strange phenomenon and the aftermath is even stranger.
While the article is interesting, the engineer makes a lot of assumptions that just don't hold water. He also states that a radiant barrier paint is made from particles of aluminum. I've never seen one that has aluminum in it. There could be one made, I don't really know. The radiant paints we use are a ceramic crystal based paint with an R&H 235 colorant of white in it. The white is there for the installer to gauge the density of the materials as he applies it. It should be opaque when he's installing it, not a solid film.
I read with interest the article by the engineer in regards to an aluminum radiant barrier attracting lightning. I had these same concerns when it first came out. You'd be basically installing a lightning rod all over your roof....with one exception. There is no current path for the lightning to follow. Like anything with electricity, it has to follow a path to make a circuit. Electricians use this all of the time to work with live wires. Don't get into the circuit or become the circuit and it's harmless. With the radiant barrier, I know of no builder that grounds the roof decking. With out the ground, there is no circuit, therefore there is no attraction by lightning. I'd be more concerned about wiring just under the decking attracting lightning than the roof decking. The wiring makes a circuit, the decking doesn't. Same would hold true of a vent hood duct out of the top of the house, or a dryer vented thru the roof. These would be far more likely to attract lightning than a radiant barrier but they make no circuit and they are not grounded. I suppose if it really bothers you that a lightning rod could be installed but I see it as wasted money. Of the few houses I've inspected after a lightning strike, while damage to the decking was evident, it was not the source of the grounding. The lightning went thru the decking to a ground source in the attic. What the engineer might be missing in his assumptions is that the radiant barrier, in that circumstance, might heat up and catch fire. Of those I've seen, it was accompanied by rain which quickly extinguished any fire. The holes blown in the decking by lightning have been from baseball size to big enough for me to crawl thru. It's also been my experience that a house struck by lightning suffers from a lot more than any fire. Most springs in the house no longer work right- like window sash balances. Most any electrical appliance is either toast or will die a lot sooner than later. Cartridges and flush valves in toilets are done or will be soon as are any faucets. It's really a strange phenomenon and the aftermath is even stranger.
While the article is interesting, the engineer makes a lot of assumptions that just don't hold water. He also states that a radiant barrier paint is made from particles of aluminum. I've never seen one that has aluminum in it. There could be one made, I don't really know. The radiant paints we use are a ceramic crystal based paint with an R&H 235 colorant of white in it. The white is there for the installer to gauge the density of the materials as he applies it. It should be opaque when he's installing it, not a solid film.
Lightning rod? Hocus-Pocus! As Trapper mentioned, where's the ground path?
The cans are ICAT- Insulation Contact Air Tight. There's a difference between IC and non-IC- but only the IC can be both (technically).
Thank you K'ledgeBldr! I understood the explanation given by Trapper and we'll not be going with a lightning rod .
For the can lights, could you please describe a little more? Are you saying these are good with insulation contact and we will not have any fire hazard? Why do they have a warning sticker which says they shouldn't be near insulation? I am confused b/w the two stickers saying two different things on the can light housing.
It is also important to understand the HOUSING is separate from the TRIM -- if the trim is not designed to prevent airflow from the 'conditioned space' into the area above the ceiling THEN the "AT" rating is NOT fulfilled.
The confusion is the "rating label" is not designed to "cover the manufacturer" from stupid lawsuits, the little tag is doing that.
Just like somebody in the legal department of all ladder makers insists on them slapping something like this on every surface of the ladder so some idiot does step off into space -- the lighting company lawyers do not want some idiot suing over their ignorance of what kind of fixture was installed when some fool turns a house into an law suit. Thus the label that "may be removed when installed in IC approved manner"... Heck, some firms even expect the installer to use the label as sort of proof they are not mindlessly ignoring the other instructions --
Make more sense?
Last edited by chet everett; 04-20-2016 at 12:47 PM..
This is not really an answer to your question, but if you use CFLs or LEDs in the recessed fixtures, there is very little heat generated compared to incandescent bulbs. Insulation contact should not really be an issue.
This is not really an answer to your question, but if you use CFLs or LEDs in the recessed fixtures, there is very little heat generated compared to incandescent bulbs. Insulation contact should not really be an issue.
Thanks! I'll eventually use LEDs but not right after moving in so wanted to find out if existing lights will be an issue.
That IS an interesting article, much better than I had anticipated. There are errors and missed points, but a lot of it is spot on.
Ignoring the aluminized paint barriers (such as some elastomeric coatings) and focusing on the panelized aluminum:
Point #1 - The electron "clouds" the presage lightning are not inches away from a roof, as in the photo with the Van-de-Graff generator. These clouds are literally MILES away from each other and in general subject to the inverse square law AND conductivity paths. Conductivity paths are readily apparent in south Florida storms, where the lighting will be far more prevalent along the face of the rain sheet any place where the air holds less humidity or doesn't have charged particles of rain precipitating in a "fresh" area. However, while the concept of: "location of the installation is that there is evidence the RBS material in a roof structure may actually “attract” lightning. is incorrect (as always), the effects of other factors make it appear correct to the lay person and the results are similar.
Point #2 - The concept of increased capacitance and small "fusable links" within the mounting of the panels is entirely correct, and very troubling as there doesn't appear to be a simple remedy, due to the structural weakness of the thin aluminum membrane and the well-known propensity of aluminum to oxidize and create areas of higher resistance. In essence when two sheets are butted together end to end and there is at best a .01 mm strip 4' long at the joint, that joint will over time oxidize. Gaps in conductivity will appear through the effects of settling, movement, corrosion from pollution or salt air and other factors. What Trapper missed is that significant currents can flow between capacitative elements without any ground. If you don't think so, grab one pole of a capacitor with wet fingers and the other with fingers on the other hand. It WILL kill you if the capacitor is large enough (even a few microfarads). When an electron cloud or strike is nearby, currents and charges are induced. A strike at one end of a house will create rings of diminishing charges around the strike, which will then discharge or equalize, creating a current flow.
Point 3# - A direct lightning strike is NOT required for there to be significant wattage flowing in nearby structures. When the bolt is determining the path of least resistance and ionizing air and materials, "false" leaders form and currents can be induced within nearby circuitry within hundreds of yards of the strike point. Literally, the path of moisture on a linoleum floor has been seen as the path of the variable high frequency electric current from a strike.
Point #4 - More accurately than "attracting" lightning, panels of thin foil could act as tuned antennas to the RF component of nearby lightning, creating current crossing the "fusable links" between panels and other metallic structures dependent upon the angle of the individual panels to the RF, etc.
Point #5 - A lightning rod near such a structure might actually exacerbate the problem, as the area within a few feet of the rod would be subject to much stronger RF signals than otherwise.
IMO, the entire subject needs further research and is a very real problem. Were I faced with a house like that in a lightning prone area I would do a few things. A. I would make sure I had a boatload of insurance. B. I would install a tall lightning rod with a properly measured ground rod at least a few yards away from the structure. C. I would seriously consider a bonded and grounded metal roof to attenuate any RF issues and provide ample ground path in the case of a strike or near strike.
The article was an eye-opener to me. I did not expect that.
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the lighting company lawyers do not want some idiot suing over their ignorance of what kind of fixture was installed when some fool turns a house into an law suit. Thus the label that "may be removed when installed in IC approved manner"... Heck, some firms even expect the installer to use the label as sort of proof they are not mindlessly ignoring the other instructions --
