Additional Insulation in Attic
 

Wife and I attended a seminar at a home demonstration on
attic wrapping an attic with a space age vented foil laid over the insulation to keep the heat from the attic off our ceilings in the house.

Also, they talk about wrapping that same vented foil around our ventilation ducts, in the attic and water heater.

Google says ventilation ducts in Florida last 15 -20 years.

Anyone know anything about this, especially wrapping the ducts in foil?

Thanks

Sounds like snake oil. Now go to BBB and check out the company, if you cannot find them RUN away very fast. Then I would contact your local electric supplier many of them have energy audit programs and they may have some information on this stuff. I would also check with Seniors against crime to see if this is a real company and if there are any complaints. Finally if you are still considering doing this, get ALL of the documentation in advance, and have a trained expert (home inspector?) go over the claims, being made. I went to 2 of these types of seminars, and saw all kinds of holes in the presentations, so I did not bite.
Please proceed cautiously.

Sounds bogus to me.

While I do not want to hurt anyone else's business, I would not recommend this for the following reasons;

1) the newer homes in The Villages have attic insulation that is an R-38. That is a good amount of insulation and there is a law of finishing return if you add more.

2) Radiant barriers stapled to the top chord of the trusses often fall down, and they lose effectiveness once they get dusty, and they will.

3) To install, the installers have to trample your existing insulation which hurts it's effectiveness.

4) None of us are young enough to see a return on investment.

While this is just my learned opinion, I have sat through hours of educational seminars on this from engineers that were much smarter than I am. I would give it a hard pass.

Hope that helps! Respectfully, Frank D.

I saw that presentation. I must say the food was very good.

The full presentation of facts was nowhere to be seen or spoken.

Your already HAVE a radiant barrier on your ducts.

The radiant barrier on the insulation that they peddle at several thousands of dollars is incredibly inexpensive the "RadiantGUARD Radiant Barrier Ultima FOIL Insulation Roll 500 sq ft | 48-inch by 125-feet | U-500-B | HEAVY DUTY Perforated Foil Radiant Barrier Attic Insulation - Blocks 97% of Heat" from Amazon is less than 20 cents a square foot. I believe the special show price was 15.00 a square foot installed for an identical product.

If you believe the presentation then buy it from Amazon and pay someone handsomely to install it any you'll save several thousands of dollars.

The main problem with the "facts" presented is you are never told how much of the home's heat gain comes from heat radiating down into the home. It's 25 to 35% if there is NO INSULATION.

Let's say that is the case, to make this example extremely favorable to radiant barrier let's say that every month is as hot as August. Since 50 to 60% of your total electric bill is HVAC let's say you have a very high electric bill of 250/month let's go even more ludicrous and say there are no fees on this bill and all of it is for electric consumption. Let's go all in and say this radiant barrier is 100% effective.

So, $250 X 60% consumption in hvac X 35% savings = $52.50 monthly savings. 630.00 annually. At the prices I was quoted it would take over 12 years to recover.

But: every month is not August and you do have insulation and a large portion of your utility bill has nothing to do with your incremental consumption.

By my calculations the radiant barrier would recover it's cost in 76 years.

I have better ideas on how to invest my money.

In our area in Pine Hills the builder used Tech Shield roof decking. Each sheet of 4x8x7/16 roof decking (oriented strand board) OSB has a film (like aluminum foil) on the bottom of it. I can tell you that it definitely makes a difference in the attic temperature. This is not my first experience with this product. Also there was a company in Ga that coated the bottom of the roof decking and any gables with spray foam insulation. It works so well there was is no ceiling insulation needed

Radiant barriers in attics may be a viable strategy for reducing cooling loads in hot climates. However, that reduction is limited to solar gain from the attic—about 22% of a home’s cooling load. So even though research has found that radiant barriers can deflect 40% of incoming attic heat, the net savings represents about 8% to 10% of a home’s total cooling costs.

Yes, they did this for a few years. Radiant barrier applied to the bottom of the roof sheathing, as yours is, is different than aftermarket radiant applications. Back then they did this and used an R-30 insulation. Folks complained about poor cell phone reception, etc., so they switched back to using regular 15/32" OSB sheathing and upgrading the insulation to an R-38. The use of spray foam on the underside of the roof sheathing is different altogether, and of course has it's own benefits and problems. Actually The Villages did build some homes with the spray foam in one neighborhood a few years ago, then returned to the use of R-38 insulation above the ceiling.

Is there anything that can stop the 3 second warm air infiltration coming through the ducts when my AC comes on?

Would more insulation wrapped around the ducts be the answer?

No.

It is not infiltration of air into the system, it is air that is already in the ducts. Short of placing a vacuum on your ducts you will always have air that heats to the ambient attic temp when the system is off.

Adding more insulation to the ducts will not help. The only way to solve the problem is to set the supply fan to run all the time on a low setting. Note that the heating setting can be set to delay the start of the supply fan for 15 seconds or so until the air handling unit plenum heats up, so that you don't get a blast of cold air. But, I don't think the cooling setting has a delay option, and it probably wouldn't help anyway.

Don’t use national statistics in Florida. We cool way more than we heat

We had cell phone issues when we moved in this house six years ago but after inquiring about it we were switched to another tower and it helped but then the problem suddenly went away. The reason TV went away from the spray foam insulation was probably related to $$$$

Thanks, I am so impressed by the feedback given related to this topic.
As one had remarked, beware of free lunches that are really just sales bait.

Had friends that bought that package. Results and savings are minimal. Just do your math. Figure out how many years it will take you to recoup the expense of your savings. You probably will never see the total savings. Best thing to this install a solar fan to draw out the heat.

If you are going to do anything in your attic, I would spray the attic roof with foam insulation. It might cost you $20,000 but we’ll worth it. We built a custom 5500sq ft home in GA using all spray foam insulation, walls and attic. When you walk in the attic, it looked like an igloo, but the attic was 70 degrees all year round, and that’s with 100 degree humid days or 15 degree nights. It is also a sealed attic meaning no vents for builders gap that allow bugs in. It was cheaper to heat and cool this house (5500 sq ft, 3 heat pumps) than our current TV house

$20,000? That would be my entire electric bill for 15 years.

Hope you got a very nice dinner out of this. Notice that they only want older people who are more gullible for these free meals.

Me too. I just learned a lot from this thread! Thanks!!

Just not cost effective. If it saved 10% of cooling bill (doubtful) , that would be less than $15 a month. It would take 15 years to break even. Scam that is sold by snake oil salesman.

Really
 

One of the all time not smart post. Spend $500 to wrap more insulation around already insulated ducts. All for 3 seconds of air!! Gotta a bridge that you would be smarter investing your money in.

You would need eight inches or more of spray insulation under your sheathing to match the blown in fiberglass that comes with the house. I like spray foam, but it is much more expensive than fiberglass. If you had spray insulation under your sheathing so you wouldn’t need fiberglass on your ceiling, you would have a large insulated but uncooled space, unless you cooled the attic as well. If you did, you might need a larger air conditioner, and you would pay to cool the attic as well.

You are talking about a totally different house design. Your description indicates that you are actually cooling the attic space with your HVAC system. I have seen this done once in NC but the home used geothermal wells to supply water as the heating/cooling heat resource for their heat pumps. This is more efficient since the groundwater is typically 55 to 65 F year round and makes heat pumps use less energy than using ambient air. However, geothermal wells need to be permitted and cost money. In TV with our small lots, geothermal wells may not be practical.

In the case I mentioned they had an entire room dedicated to the HVAC condensers and geothermal water heat exchangers etc. Perhaps in Florida the equipment could be located outside since winterization is less of an issue, but you may need some equipment covers etc. that may need ARC approval.

None-the-less, spending 20,000$ for spray foam plus some more for geothermal wells and geothermal HVAC takes a very long time to recover your investment.

If your previous house used geothermal wells as the heat source/ heat rejection pool, I suspect that your lower heating/cooling costs are due to the geothermal water temperatures and not to the spray insulation.

Your hard ducts are made of a fiberglass and glue product with foil on the outside. Adding another thin layer of foil wouldn’t help at all. These inch-thick hard ducts don’t insulate very much, but they insulate far more than the metal ducts used in past decades. You could add insulation by attaching foam board to them somehow, but I don’t know how much it would save you.

Attic insulation around here has often been trampled down by workers and isn’t working at its peak, so that R-38 may actually be R-15 in many places. Probably the most effective way of cutting your cooling costs would be to have another foot of fiberglass blown in. This is fast and not too expensive. It would also cover up most of the soft ducts (two layers of plastic bag material with a little bit of fiberglass and a coil spring in between). Then those ducts would have, say R-20 insulation around them instead of R-1. I wouldn’t be surprised if this cut your electric bill by $500 a year.

BTW, the home that we went to covered their complete attic with this super duper space age vented foil, added a solar fan on the floor, bought some added lubricate for their AC, for over $10,000.

Had radient barrier installed when house built 20 yrs ago. Glad we did. House cooler in summer and get to use the attic as it’s not too hot. Would recommend it. Researched it ourselves before building. Saves money over time and home more comfortable immediately.

If you are responding to my thread, no, we didn’t cool the attic. Our builder only used the spray foam that was over 10” thick on the attic roof. There are 2 kinds of this insulation: closed cell and open cell. We had friends that retrofitted their attics with the open cell spray foam at a cost of $8000 for a 2400 sq ft, and their attic in the middle of a GA summer was also 70 degrees. There is no magic to this. The other benefit to this in GA is your furnace lasts longer because they are located in the attic. A furnace running in a room at 70 degrees will last longer than a furnace running in an attic at 140 degrees

Wonder if heavy duty Reynolds wrap would do the same as this super duper foil for a bit less money.

I attended the same seminar and even had the speaker come to my home. He went into the attic and took pictures. Sure enough, I was losing energy and things were "a mess" up there - the pictures "confirmed" this. he was a great salesperson and I seriously considered this $10,000 "improvement." While I was thinking about it he went to my neighbor's house and guess what? She had exactly the same issues I had and the pictures he showed her were identical to the ones he showed me. My advise? Run don't walk away from this scam!

We went to that presentation as well. The assumptions presented were ludicrous. I agree with many saying the payback period is ridiculously long, if it ever happens at all. Btw - I am an engineer and this “investment” wouldn’t pass muster in any business. Save your money.

Years ago I worked for a utility company in PA as an energy conservation specialist. We always taught that when installing insulation anywhere in the house, the vapor barrier went toward the heated side in winter. In Florida it would be the air-conditioned side or your living space. In the attic, the vapor barrier would go against the floor which would be directly above the ceiling of your home. Insulation could be added above that. If a vapor barrier was placed on top of the insulation, it would trap moisture which would condense and wet your insulation below it, therefore reducing your R-value as well as causing moisture problems in your home. A radiant barrier is different than a vapor barrier. A radiant barrier reflects heat outward. That is placed on the roof rafters, not on top of your insulation. As to interfering with electronics, that depends on the material that the radiant barrier is made of. Not all radiant barriers are the same. They are different in their components as well as their thickness and of course like with anything, you can get an excellent product and have a lousy application. Remember too that your soffit vents should never be blocked. That is important to allow airflow from the floor of the attic up to roof vents, ridge vents or ventilation fans. Ductwork should be wrapped in insulation because most of the time it is run in unconditioned spaces: in your garage or attic where the temperatures are very hot when you are trying to air condition your home or when the temperatures are cool and you are trying to heat your home. Most utility companies have people to help educate homeowners and government or university sites online are also helpful. It’s best to get your information from a place that is not selling any product. I have always added additional insulation in homes I have lived in. In our Florida home, I researched radiant barriers and we did have them installed from garage through covered lanai. That has made our attic space cooler which is good for anything you have stored up there but primarily for keeping the house cooler since the space directly above our ceiling has dropped in temperature.

The expression is there is no free lunch. They are bribing you to attend their sales pitch.
We went to one where they wanted to manage your investments. They handed out forms which many, most people completed. How could you say no to someone who bought you lunch? Mine was BLANK.

My comment is based on your post: When you walk in the attic, it looked like an igloo, but the attic was 70 degrees all year round, and that’s with 100 degree humid days or 15 degree nights. . That is impossible without using your HVAC to condition the attic temperature unless you had your house set at temperature much lower than 70F in the summer and much higher than 70F in the winter. The attic space which is between two very different temperatures zones will gradually change to a temperature somewhere between your conditioned house space and the outside air. Insulation slows down the temperature change but can not stop it. Since the outside temperatures keep changing, the attic space will continue to change but will remain between the two temperatures for typical temperature rate changes. This is fundamental Thermodynamics.

With 10 inch foam on the roof and no insulation in the ceiling of the home, heat transfer from the home will be greater than heat transfer through the roof insulation. You also stated that the attic was sealed with no ventilation so the heat transfer is basically across the insulation and ceiling. The attic temperature will tend to be closer to house temperature than the extreme outside ambient temperatures. If your 70F comment was "~70F in winter and ~79F in summer" I could see that happening. Your inside house space is cooling the attic somewhat in summer and heating the attic somewhat in winter. Again it depends on what your house temperature is.

Nobody is talking about reducing the attic temp by passive means.
I came from Kansas where we used wind turbines on houses to draw up cooler air from soffits and exhaust hot air out of the attic. I know there are solar fans that you can replace a existing mushroom vent on the roof but they can tend to draw in air from nearby exhaust vents and just circulate air between vents instead of from soffits.
What is the recommended number of exhaust venting for a home?
My new home in St Catherine’s has only 2 mushroom and very small amount of ridge venting because of lack of ridges.
I’m just guessing that since all of the soffits are open for venting, increasing the amount of exhaust vents or adding turbines has to help reduce the attic temperature for a minimum amount on money spent.
Anybody have an answer?

Reducing attic temperature
 

Nobody is talking about reducing the attic temp by passive means.
I came from Kansas where we used wind turbines on houses to draw up cooler air from soffits and exhaust hot air out of the attic. I know there are solar fans that you can replace a existing mushroom vent on the roof but they can tend to draw in air from nearby exhaust vents and just circulate air between vents instead of from soffits.
What is the recommended number of exhaust venting for a home?
My new home in St Catherine’s has only 2 mushroom and very small amount of ridge venting because of lack of ridges.
I’m just guessing that since all of the soffits are open for venting, increasing the amount of exhaust vents or adding turbines has to help reduce the attic temperature for a minimum amount on money spent.
Anybody have an answer?

Hey hey! Throwing stones you just might hit someone :bigbow:

I don’t know what the talk about 10” of foam is all about what I saw in attics in Ga was more like 3” but a complete coating of sheathing, rafters and gable walls

See OP post #32 rsmurano:
If you are responding to my thread, no, we didn’t cool the attic. Our builder only used the spray foam that was over 10” thick on the attic roof. There are 2 kinds of this insulation: closed cell and open cell. We had friends that retrofitted their attics with the open cell spray foam at a cost of $8000 for a 2400 sq ft, and their attic in the middle of a GA summer was also 70 degrees. There is no magic to this. The other benefit to this in GA is your furnace lasts longer because they are located in the attic. A furnace running in a room at 70 degrees will last longer than a furnace running in an attic at 140 degrees

That's the source of 10 inch foam. You may have seen closed cell foam which has double the R value of open cell foam.
Over and out. This thread has passed the point of diminishing returns.