Teach me about attic insulation/heat barriers... (Surprise: new house, transfer)

[SportyandMisty]

Notice the design flaw: the air ducts are in uninsulated space. So, in summer, cool air is going through those ducts, but the ducts are in a very hot attic. A better design, sometimes called cocoon insulation, is for the insulation to be up against the roof so the attic itself is insulated and will be cooler. To do this correctly, you do have to be concerned with proper venting, but again that was an original design issue.

[Burning Madolf]

As I understand from a friend who just installed the radiant barrier and additional research on my own, this product works in two ways: 1) absorbs/reflects heat coming off the inside of your roof and 2) if properly installed, creates a pathway for the "cooler" air coming into the attic via soffit vents to mix with the hot air between the roof and the barrier. The key is then how the super heated air gets out (gable, ridge vent, fan).

Done right (allowing for proper air flow) along with a thorough insulation job should make as good a difference as possible. However, attics are tricky and if things are done wrong (restricting air flow for example) you can cause more problems.

[HX_Guy]

Hmm, I store a bunch of boxes up in the attic that are pretty tall...I wonder if that is messing with the airflow and ventilation and making things worse.

[ReadyFreddy]

78 degrees is pretty cool. Have you looked into 'time of use' plans to see if those would save you money?

[Zippyman]

I've done the research & read the complete reports about radiant barrier- if you were to do that yourself, and read between the lines, I think you'll find that real, blown-in insulation is far more cost-effective than radiant barrier. The published studies you'll find on the net ( often linked to by those selling radiant barriers ), don't really say what the salesmen tout.

If you have little/no insulation,radiant barrier will give you an impressive bump in your bills, but it does nothing to prevent conditioned air from leaking into your attic. Blown in cellulose actually slows down leakage around light fixtures, ductwork & other penetrations to the living space. In addition, it is an effective & cheap insulation. It works, that's why new homes are required to have it, or some other *real* insulating product installed by code. Radiant barrier isn't required by any building code for a reason, it- by itself- is almost worthless.

If when building the home, all penetrations are sealed, the ductwork is sealed, and the home is properly insulated, a very small gain in performance can be achieved by adding radiant barrier. It won't pay for itself quickly.

From the pictures posted, you don't have nearly enough real insulation- perhaps 6" at best, which would give you an r-value of about 18-ish. New homes have a ceiling r-value of 38 to about r43. You really need about 10 more inches of cellulose to maximize your savings and comfort.

My own home is a touch smaller than yours ( about 1600 sq foot ), and when I bought it it had a similar amount of insulation. I added 10" of cellulose, and the difference in comfort was amazing. We had it done in mid-May, when daytime temps approach 100, but nights are still fairly cool. Our heat-pump had been spooling up at 8 am, and after the insulation was installed it didn't kick on until 9 or 10 am, and when it did kick on, it didn't run for as long. We made several other changes to improve the efficiency of our home, but I personally think we got the biggest "bang" from the insulation.

The cost for us(a couple years ago) was about $800 for 10 inches of cellulose installed over the house *and the garage* (probably 1900 sq feet) so your quote of $ 1 per sq foot seems about double what it should be for installed cellulose.

Fwiw, I've made a lot of upgrades to my home- an 18seer two-stage heat pump, new doors & windows, a "heat pump" water heater, sealing ductwork & re-engineering the return-air setup for my heat pump. Many of those upgrades werent really done for a quick payoff on savings, but to improve the comfort of the home. Cranking the thermostat down to 68 and leaving it there *all summer* without ever seeing a bill over $275 (including taxes & after a bunch of rate increases!) makes living here in the summer much more bearable!

I'm sure people here will chime in and tell you how low their bills are, but the question to ask is how low their thermostat is set at. I can't sleep when the house is at 80, even if I *could* lower my bill by $100 in the summer- so count on "giving back" at least some portion of your "savings" through a lower thermostat setting. If you read those studies done on radiant barrier, most people ended up lowering their temps.

[HX_Guy]

Wow 68º! That's down right cold!

I have a feeling that we got quoted about double of what it would normally cost because of the fact that it's in 90% trade, so with the garage figured in as well, it would be ~2300 sq ft, or $2,300 but only $230 out of pocket which I'm ok with.

Does your house have vaulted ceiling (angled) or flat throughout? Half of our house (literally the whole south side) is vaulted celings while the other half is flat 8' ceilings and the area where the attic is.

Can insulation also be added to the area where the ceilings are vaulted or is there not much that can be done there since they is very little (none?) crawl space.

Front of the house faces east (and where we spend our morning - afternoon in the home office) and the back of the house faces west, where the living room and master bedroom is, where we are in the evening at at night. It's pretty much in the worst orientation possible.

[Zippyman]

Our ceiling is vaulted to about 16 feet, the attic over the vaulted part is still very tall though. You might be pleasantly surprised if you peek into your attic, even if the ceiling is vaulted, the actual roofline is usually still several feet higher on the homes that I've seen, so access for pros isn't usually a big deal. I would personally be really nervous about "joist walking" over a vaulted ceiling, but the crew that did my house didn't seem bothered by it at all.

I'm about as cheap as they come, but I couldnt justify trying to install blown-in insulation myself. The crew came on and knocked it put properly in just a few hours, no mess, and not much over the retail price of just buying the insulation & renting the machine myself.

[HX_Guy]

Originally Posted by ReadyFreddy

78 degrees is pretty cool. Have you looked into 'time of use' plans to see if those would save you money?

We are on a "12pm - 7pm time of use" plan with APS so we don't use things like the dishwasher or washing machine during those times, but the AC has to keep running especially since we work from home.

78º is "ok" but I prefer 77º...you wouldn't think you could really feel a 1 degree difference but I instantly know when it's not 77º in the house. As Zippyman said, I would rather spend $50 more or whatever per month and be comfortable than be miserable...I get very irritated and short tempered when I'm hot.

[HX_Guy]

Ok so I went back up there to check it out some more and there is definitely some good crawl space above the vaulted part but there is also pretty thick insulation there as well as you can see...can more be added...should more be added?





The area above the garage has ZERO insulation which is nuts.

[Burning Madolf]

Keep the soffit holes free. Maybe tack up soffit vent chutes before blowing in insulation to make sure.
Here's what they look like:
https://www.google.com/search?q=soff...w=1920&bih=930

After your first layer of blow in is done, you could role out the pink stuff perpendicular to the rafters.