Six weeks of effort. (off and on) And only 2/3 complete. I'm really happy with what I see.

We've had the AC turned off for the past 10 days. I know temps have been mild (low to mid 80's) but the house temp never got above 77 dgrs.

WSW side of house.


SE side.


SE side again.


NW side.


R30 sure was fun.


Replaced all 36 Soffits. After I removed the first vent, I could feel the draft. (suckage)

ttt

any more experiences? regrets?

The April electric bill was $100.01. Last year it was $151.98.

If you're thinking about this in the Dallas area, this is my neighbor:

http://www.eco-attic.com/3601.html

I'm sure he can answer any questions you have. Ask for Jordan.

Does anyone have any recommendations on installers in the Cedar Park/Austin area?

I just got a quote from EAS.

House is 2 story with 1300 s.f. attic. Quote is $1350 and includes 5 inches of insulation, a fan and more vents vents.

Based on this thread, that looks like an acceptable price.

Recently got spray on RB through this company: http://www.txenergysaving.com/index.php

They also bumped me up to 30" of insulation with Oncor paying $300 and sealed my A/C unit and house for free paid by Oncor. (Have to have Oncor and have to be an all electric house). Cut my bill 30%. Really nice guy too.

Need to get this done

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sealed my A/C unit and house for free paid by Oncor

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How do you "seal a house"?

heard about this product on a home improvement show over the weekend

I looks like good stuff and affordable. I'll probably try to put if up once it cools off in the fall/winter/spring.

http://www.atticfoil.com/

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How do you "seal a house"?

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You seal a house by locating and fixing areas of unwanted infiltration/exfiltration - door seals, window seals, fixtures/switches in exterior walls, attic door, etc.

It has the potential to save you a lot of money.

Very interesting subject (especially since today was our 24th 100 degree day).

I do have a question due to a question (that never got answered) I heard on the radio a couple of weeks ago: If you install a radiant barrier, does it shorten your roof/shingle life due to the trapped heat?

If this was already asked/answered; I apologize in advance as I didn't see it.

That is a very good question that has never been adequately addressed. The best radiant barrier is a silver colored roof surface so that no heat is radiated back through the decking and roofing. Those who favor the underside barrier will quickly dispute this, but I have experienced it first hand.

Thank you for that info fire... i'm sure there is prolly a lot of different takes on this. I'm gearing up for research

Let us know what you find. My opinon as stated is open to new info.

[This message has been edited by fireinthehole (edited 7/8/2011 9:50p).]

So far; I'm finding that it shouldn't shorten the life of shingles since they are designed to handle temperatures well within the range that would be added by a barrier. Some links:
http://www.mccoys.com/library/radiant-barriers-question-and-answer-primer-FAQs
More technical: http://www.rimainternational.org/technical/tb103.html
http://www.radiantbarrierguru.com/the-effect-of-radiant-barriers-on-shingle-temperatures-am-i-going-to-bake-my-shingles/

Basically, your shingle temp will go up 2 to 5 degrees which isn't significant enough to shorten their advertised life.

I'm going to keep looking though and post if I find anything different.

RB is a mother fuc*** when it moves cooler in the attic to lower energy costs. Please tell me where I'm wrong.

Cooler in the attic is way good. Just saying that going to a silver/aluminum colored metal roof dropped my attic temp substantially ( about 30 degrees ). I can now place my hand on the roof surface on 100 degree days without blistering my hand. Makes more sense to me than a barrier under the roofing structure. Any increase in temp of your roofing and decking decreases the life expectancy, it is just a matter of how much, 3%, 10% ? This has to be compared with the decrease in energy costs, and a bottom surface RB may still be a good economical decision based on that. Not everyone can go to a metal roof. I already had one and just painted it with aluminum paint. Even so, the lighter your roof color, the cooler your attic will be.

AginKS, it has been my experience as an engineer that none of the shingles last their advertised life, in South Texas at least. An asphalt comp roof in Texas, no matter what life shingle you buy, is doing very very good to last 20 years before needing to be replaced. The thicker asphalt comp shingles actually can have a shorter life due to the thermal gradient and curling of the shingles.

As you move north into the higher latitudes, which results in less UV, the shingle life increases.

[This message has been edited by fireinthehole (edited 7/8/2011 11:29p).]

[This message has been edited by fireinthehole (edited 7/8/2011 11:32p).]

Radiant barrier is a service my company offers, its my honest opinion that anyone with enough attic space should have radiant barrier foil in their attic. If anyone is interested I would be willing to give all the knowledge I have about it. If you're on the fence I have some info that should make up tour mind.

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silver/aluminum colored metal roof

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have there been a rash of plane crashes near your house due to blinded pilots?

White/light grey composite shingles work just as well. So do the new generation of shingles that are basically a radiant barrier with a composite stone glued to them with something besides asphalt.

My IR thermometer disputes the 2-5 degrees claim on siding, so I'm not sure how it could be different for a roof. (Part of my house has Hardi with foil back OSB behind it, and part has Hardi with regular OSB behind it -- the temp difference is > +10 degrees F when the sun's on it, and closer to +30 F after a day in full sunlight.) The hardi will retain some excess heat, but that's a dramatic difference in numbers.

I still maintain that the radiant barrier on the inside of the attic is snake oil at best and harmful to your house at worst. Before you consider radiant barriers, you should have full-length soffit venting, soffit baffles and passive ventilation designed to keep air convecting out of your attic, and the insulation in your attic should be at least R-46 and probably R-60, INCULDING areas where you might have planks for storing things in the attic. Those items are ALL much lower hanging fruit than adding radiant barriers and are proven not to be harmful to your house. Even then, I'd do my best to keep the IR/UV on the outside of the house rather than allowing it in and trying to reflect it back out.

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I still maintain that the radiant barrier on the inside of the attic is snake oil at best and harmful to your house at worst.

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Have you been in an attic with radiant barrier?

Yes.

Have you ever been on a roof with radiant barrier under it? My sneakers melted.

Have you ever been on a roof with a proper radiant roofing material? My sneakers were fine, but I think my taint got suntanned.

Sorry superspeck, but most of what you just said (outside of having high R values on insulation) is incorrect.

Just having a lighter colored roof does not automatically equate to the same or better performance that a radiant barrier will provide. It would be completely dependent on the type of roof composition of the roof surface.

Radiant barrier is far from snake oil. It is a proven technology that works. I invite you to go stand in an attic that has it and then compare to one that doesn't on the same day. There is a difference.

The reason radiant barrier works so well is that it prevents excessive heat gain in your attic space. You can delay the heat transfer into the cooled area with better insulation, but insulation is not a complete barrier - it merely slows down the heat transfer, it does not prevent it (hence the "R" meaning "resistance").

Additionally, even with a high R value insulation, if you are still allowing the heat gain in your attic, your central AC and heating unit (in the winter) become less efficient due to having to overcome the heat load to operate properly. In the summer, your duct work has to overcome the heat gain in the attic before it can truly cool the living area. This means it runs longer, which translates to higher utility bills. Same issue in the winter time as well.

Bottom line - if you don't allow your attic to absorb the summer heat, your insulation and cooling equipment become exponentially more efficient. That translates to longer equipment life and loewr utility bills.

How is it snake oil if people are saving money electricity and able to keep their houses cool in the heat of the summer?

I can see why you might think there's a better way, but snake oil?

The attics that I have been in with radiant barrier are obviously much, much, cooler.

I guess a better analogy is that radiant foil in your attic that is like putting a tinfoil hat on your house. It doesn't really do much, but those who think it does sure believe it.



Disclaimers -- I'm talking exclusively about retrofit situations in south Texas (IECC 2009 Zone 2) here. New construction can and should have several engineered solutions to some of these problems that make radiant barriers, roof deck insulation, and other systems both passive and active into a good decision.

Re: roofing material -- lighter roofing material will do about as much as radiant barrier just because it's got a higher albedo. If you're considering doing all the work of a radiant barrier, though, you should look into Energy Star rated roofing materials -- some of them are really neat. I really like the stone-coated stainless steel panels... about 50% more than 30-year asphalt shingles, but they're 50 year rated, won't be damaged in a hail storm, and provide fire protection -- while still looking exactly like an asphalt shingle.

Excessive heat gain in an attic space is a failure of passive ventilation in your attic space. Active ventilation (attic fans) can be bad because they can pull air out of your house. Having an excess of soffit vents and enough air exchange out the top of your attic should keep the attic 10-15 degrees warmer than the outside air, max.

Most attics I've been in have been dramatically undervented; the calculations that the industry uses are based on the square feet of the attic and inflow/outflow balance, and are not based on how of the air inside the attic is exchanged. So while it might be "right" to have a 2.5 story house with a 1200 sq foot 2nd floor have only 32 linear feet of peak vent offering 18 free inches per foot, by my back of the napkin calculations, you only exchange the air in that attic once every five hours, which is why your attic is hotter than the outside... the air sits in there to get heated. Add a continuous soffit vent all the way around the house and the peak ventilation you need & the air exchange rates change by a lot.

Tinfoil in a window isn't very effective at blocking heat/light coming in -- the solution is to use a low-e coated glass and a dual pane window. The same is true for radiant barriers in your attic.

[This message has been edited by superspeck (edited 7/11/2011 11:13a).]

My April elec bill was $106.00.

My May bill was $127.00.

Woooohoooo!

Got quoted $650 for the foil and $900 for foil and insulation. I'm think about the $650. How much will the electric bill drop froM the foil? How much will it drop with the foil plus insulation?

any idea on the difference in electric bill with your neighbor?

Dlance, what were your comparable bills from the previous year?

I don't think there is a question that the attic is cooler with a RB. The question is really is the roofing and siding with RB significantly hotter due to the back radiated heat, and is there a better way rather than letting the heat thru the envelope material and then radiating it back through. I and some others think there is. However, retrofit cost on an existing house vs. benefits has to be a big factor in making the decision. The long term cost of reduced life of the envelope material has not been clearly defined and is the wild card I believe.

It sounds like you may be saving between 50 to 100 bucks a month.