radient hear barriers, like in Florida
Anyone using this stuff- its like aluminum foil to go in the attic
Anyone using this stuff- its like aluminum foil to go in the attic
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Replies
I have mixed opinions and I live in Florida. Some guys are even using the OSB where the barrier is already attached.
So the debate is whether is really important to keep the heat out of your attic or just make sure the insulation at the ceiling is good enough. Many guys I know are afraid the radiat heat barrier keeps too much heat at the roof deck and "cooks" the shingles from underneath.
Not sure if thats a good theory or not but I guess it will take a few years of using the barrier to find out.
I think the real answer is to maximize your attic ventilation. The closer you can keep that to ambient air the cooler your house will be.
gfretwell,
I think you are in Florida as well? I ask because I wanted to see if you had read any of Listrubek's (sp?) reports? Isn't he the one that is saying more attic ventilation is a bad thing due to moisture intrusion?
I really get confused on what to believe here in the Sunshine State anymore. :)
I may be in the minority opinion but I believe northern thinking doesn't work in SW Florida. Attic insulation is not as big a deal as it is when you are trying to hold the heat IN. The radiant barrier should be om top of the bottom truss chords along with the vapor barrier
I am a Mainer and I only respond because I like talking about this stuff :)From what I have read a vapor barrier always goes on the warm side of a building assembly- int. in cold climate and ext. in a warm. That said, you will know where to put it and the insulation by drawing a thermal boundary around the structure you want to condition ( heat or cool). It should be a clean, uninterrupted line dictating what is space you want to condition and what you want to be the ambient air temp. Therefore, if it is a cathedral, you insulate the roof to keep out the warm, humid air from the outside. If you have a truss roof you would insulate the bottom cord and in both cases air seal like you mean it. As far as the vent-less roof (Lstiburek, and the "L" is silent)I think is mainly in cold climates, and it is only used if the ceiling and air tightness of the house are Top-Notch. If no hot air leaks into the roof, why ventilate? I myself would NOT try this approach....many Maine carpenters would roll over in the graves...
I'm in So Cal, and I resheathed my garage roof with it. I found it made a huge difference in temp. Without insulation, heat went from unbearable to bearable.
Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Save the Whales! and Guns!
I want to recess all my window and door openings on my home where I have some extreme heat and cold conditions. Sacramento area of calif. I Have 6' walls with R and 8"rwd ship lap siding with tyvac behind it. the siding is cupping so what I was thinking was to fur the walls by 1 1/2" and sheet it. then stucco the building. My consideration is should I use some type of radiant barrier either in a roll over ply or osb with barrier already attached? I will have an air space of 1 1/2" but i don't know the effect the stucco will have with reflection. The color of the stucco will be lite. feedback will be most appreciated and design can be changed.
In your case, you may find that a THICK (1") layer of stucco will make more of a difference than anything. Putting that in front of a radient barrier... honestly I'm not sure of how much of a difference you will feel. It's not bad by any means, but I would make sure the rest of the interior envelope was taken care of first: Ceiling penetrations, foaming gaps, sun shades in the summer, proper storm windows in the winter, attic insulation and venting, that sort of thing.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Save the Whales! and Guns!
LOTS of debate about this type of thing. Whether it works depends on the specifics of the application. Whether it is worth spending a lot of extra money and/or effort also depends on specifics. Remember, radiant/reflective materials only work if they stay reflective. When they get dusty/dirty, their effectiveness drops dramatically. The guy that resheathed his roof probably spent little extra $ for the sheathing (I've seen this stuff), and nothing for the install, so he put out little effort or money. Also when he was done ... he realized a big difference. This performance may or may not last a long time. Radiant barriers have show dramatic improvements ... under laboratory type conditions. The key ... do they have long term staying power?
Even surfaces that aren't horizontal facing up can get dusty and dirty over time ... will that be the case for you? Don't know. IMO, I wouldn't necessarily pay a lot for this to be installed. Just my opinion, though. You/we may get an earfull on this topic, though. You might do a search in this forum ... also do a search for some research papers on the effectiveness of radiant barriers ... I think there has been a lot of study on the topic.
ehh that reminds me of the time a client's neighbor was telling me about his $12,000 roofing job. He had the contract state that foil faced OSB placed foil side down would be used on the roof. Well, when they were done it turned out they didn't use the reflective OSB on it. Apparently the supervisor didn't do much at all and just let his crew bang away. The HO pointed to his contract and sure enough the roofing company (an established local company) had to tear out the new job and put a new roof on with the foil faced OSB at no extra charge. Ehh.
Handyman, painter, wood floor refinisher, property maintenance in Tulsa, OK