Here's a little design/planning detail to consider if you are thinking about decking a lot of your non-airconditioned attic for storage/whatever:
Ceiling joists range from 2x6's to 2x12's. I wouldn't deck over any area less than 2x12's if you are planning on adding live loads to the area. In addition to that, since 2x12s are actually only 11 1/4" wide you won't have anywhere near the amount of room necessary to attain the minimum R-30 insulation value that is suggested with any type of blown-in fiberglass or cellulose. Someone ought to come out with high-density/high R-Value Insulation Blocks that could be trimmed to fit between ceiling joists to get R-30+ insulation value in less than 11 inches.

What is that radio show called on KTOK around 11am on Saturday, where they answer house questions? I caught about a minute of it while driving on Saturday, and I got in on the tail end of an attic ventilation question. The host had a brilliant trick for getting some extra "soffit ventilation" by opening up your garage door and pulling down your attic ladder opening. He was helping a guy diagnose whether he needed more vents on top or more soffit ventilation. Now I know why maybe I see people doing this once in a while in very hot weather.

Let's suppose you are going to work up in your attic in the early morning (for whatever reason). Raise up the garage door and pull down the ladder a few minutes before you start and maybe you'll get a few degrees cooler temps from it.

I didn't have my house built with the attic entrance in the garage, because I didn't want to have to move a car every time I wanted to go to the idea. So I had it put in the hall. That's also a good reason for not having your storm shelter under the garage.

That's also a good reason for not having your storm shelter under the garage.

I have an above ground storm shelter and i never understood or why people would move their car out into the hail / rain while a tornado is coming at them to usher their fmaily into a hole in the garage floor.

Let's suppose you are going to work up in your attic in the early morning (for whatever reason). Raise up the garage door and pull down the ladder a few minutes before you start and maybe you'll get a few degrees cooler temps from it.

I've done this a few times and it does work pretty well to get a strong breeze going through there.

I have an above ground storm shelter and i never understood or why people would move their car out into the hail / rain while a tornado is coming at them to usher their fmaily into a hole in the garage floor.

Not to mention the fact if the tornado goes over your house, you could become trapped in that shelter. Always call a neighbor to let them know you're going in there.

That said, I want to say that last year (2011) a tornado went through Norman and relocated a house on top of their shelter, and they were trapped for a few hours. They still had a cell signal and were able to call, but that is a nightmare for claustrophobics like me.!

Sorry if this thread is dead, but the info is still very much relevant. Thanks for the information on attic ventilation. I have written a couple of articles detailing how to conduct a DIY home energy audit. I didn't get into too much detail for the attic, but will be adding many of the points discussed in this thread. If you would like to read them they are on our company blog at http://www.sprayfoamdirect.com. The articles are here:
Conducting a Home Energy Audit – Insulation
http://www.sprayfoamdirect.com/blog/2012/08/conducting-a-home-energy-audit-insulation/

Conducting a Home Energy Audit
http://www.sprayfoamdirect.com/blog/2012/07/conducting-a-home-energy-audit/\

I hope that you will find these articles useful. Please let me know if you have any comments or questions about the articles, spray foam insulation or conducting a home energy audit.

Thanks!

Just a bit of an update...

This summer has been painfully educational for me in the HVAC world. While I was successful in cutting some of the heat in my attic, I have found that my home HVAC system is costing me a fortune for a pretty simple reason - my ductwork is not laid out properly.

I started in on a bit of this information back in the OGE SmartHours thread, but thought I'd continue it here.

I've started burning somewhere in the neighborhood of 30-50% more electricity than I believe is reasonable or expected, and every time I query a comparable or older home, my suspicions get reinforced.

Turns out I was right.

An HVAC contractor came out and looked at my ductwork and said, basically, the original vendor used by my builder didn't know much about airflow and system sizing. The system does not provide enough return air for the amount of cooling its supposed to provide, and that's causing the system to run horrendously inefficiently. That same vendor said that it was possible to reduct the system to alleviate the airflow problem, but the expense of doing it would represent a significant chunk of the cost of an entirely new system, and given that mine is 13 years old, it didn't seem like a prudent expense.

The bottom line? If you're building a house, or getting a new HVAC system installed, *insist* that your HVAC vendor perform a full heat load analysis on your home. Do *NOT* let an HVAC contractor sell you a system based solely on your square footage. A heat load analysis involves taking into account the entire physical space of your home, your windows, the size of the exterior walls, the type of roof, you name it. The notion of "500 sq ft per ton" as "rule of thumb" just doesn't cut the mustard anymore.

The HVAC contractor who told me the reducting was cost prohibitive was stunned at my current monthly cooling expense, but said its all because of improper equipment installation. He said I had good equipment, but it was simply installed improperly, and subsequent discussions suggested to me that the builder, at a minimum, should have caught it. I was stupid and didn't know better, and I consider myself to have a better-than-average education in matters relating to home construction.

My situation is so frustrating because it appears that no aspect of current OKC codes requires any kind of certification or commissioning for proper ductwork sizing and performance relative to the system being installed. Generally speaking, so long as your furnace is installed such that it won't gas anyone in the house, that's what the codes are for; but if that ductwork causes you an extra $150-$200 in electrical consumption each month due to incompetent installation, there is *absolutely zero* consumer protection.

One contractor told me that my current equipment, over a typical Oklahoma cooling season, should cost me about $400 to operate - based on a 75* internal (house) temperature and 95 outside temp, and about 1400 operating hours. My bills are running about that much every month, with my thermostat stuck on 78*. And few if any HVAC contractors are interested in doing anything in my attic right now, with temps in the 120s and up. So I'm stuck.

And its incredibly frustrating.

All I can do is get a load calc, wait until fall when the vendors aren't as busy, and look at getting new equipment and ducting. Fixing my current problem doesn't even sound feasible at this point.

And I may start a push with the city of OKC to modify our residential building codes to demand a certain performance testing level before an HVAC system is commissioned for retail sale. As I said, the consumer in my position has absolutely zero protection -- and I'm equally sure I'm not the only homeowner with this problem, meaning that hundreds - if not thousands - of folks are blowing money right through the roof because of incompetently installed HVAC systems. HVAC installers don't care because they get a check from the builder, and the builder doesn't care because he doesn't pay the electric bill. And the homeowner is left holding the bag.

Beware.

But my contractor said water might get in the ductwork if placed in slab.

Happens a LOT. I've seen many homes where the heater was moved to the attic due to failed slab ductwork.

This is kind of on subject. When we replace our current roof im going back to the older style turbine vents.

At different times in our lives we have lived with both and now currently have the 'newer' style powered fan vents. They do work pretty well but during times of the year like we are having now they run the majority of the day even set at 120 degrees - I've hooked mine up to a timer so it runs from 2-8pm instead of nonstop. They also make alot of noise, (you can hear a slight hum inside the house if you are listening to it, by no means will you have to turn up the tv) and the money they save you in A/C cost are over powered what it cost to run both of them.

The turbines work well for the weather in oklahoma because we always have wind but you do have the inconvience of climbing onto your room and covering them during the winter.

IMHO turbines are your best option. Electric fans burn out and ridge vent "filters" clog up. Turbines have lost popularity because they aren't as pretty as other options...

I just recently finished the construction of my own home. I used the spray foam to completely insulate the whole house. The garage,the walls and the roof. I have no vents in the attic whatsoever. I had an 18 seer heat pump with gas furnace installed upstairs and the same setup installed downstairs. I have been using the gas furnace most of the winter to heat the home as well as for my gas tankless and cooktop. My gas bill has been $75-98$ a month and the electric bill is between $88-98 month. THe house is around 3950 sq ft

I just recently finished the construction of my own home. I used the spray foam to completely insulate the whole house. The garage,the walls and the roof. I have no vents in the attic whatsoever. I had an 18 seer heat pump with gas furnace installed upstairs and the same setup installed downstairs. I have been using the gas furnace most of the winter to heat the home as well as for my gas tankless and cooktop. My gas bill has been $75-98$ a month and the electric bill is between $88-98 month. THe house is around 3950 sq ft

If I were building from scratch, I'd sure give the spray foam a good, hard look. Just seems to make too much sense (cents?). Heck, if it weren't so expensive, I'd spray my current attic :)

Spray foam is the best IMHO. The 18 seer AC is somewhat pointless with such a low heat gain. Ill bet they sized it close to 500 sqft per ton even though your heat gain is much lower.

If I were building from scratch, I'd sure give the spray foam a good, hard look. Just seems to make too much sense (cents?). Heck, if it weren't so expensive, I'd spray my current attic :)

What do you deem "so expensive"? Our attic was roughly $6000... on a 40' x 40' house with a pretty good roof pitch.

A big point about spray foaming the roof is the air handler/furance and ductwork is in conditioned space. That alone saves an average 25% on your heating/cooling utility bills. You can reduce the HVAC system capacity about 25% just for that. Overall, spray foamed homes can get by with over 1000sqft per ton for the AC where an average house is closer to 500sqft per ton.

What do you deem "so expensive"? Our attic was roughly $6000... on a 40' x 40' house with a pretty good roof pitch.

Well, $6k is a lot of money to me, thus its an expensive proposition. Obviously not everyone would necessarily agree that's a lot of money.

Well, $6k is a lot of money to me, thus its an expensive proposition. Obviously not everyone would necessarily agree that's a lot of money.

It's all about payback time. How long would it take to get teh $6,000 back in energy savings....
Too long if it's a retrofit for most people. When done as part of new construction you could subtract the cost of conventional insulation saving some $$$

So roughly $5 per SF of floor space for the 40 X 40 attic foam insulation application. Our 2200 sf home would run $11,000 at that same cost factor. We had R-50 cellulose put in when we built our home at a cost of > $2,000. Our total electric home's utility costs per month have been under $150. That $9,000 extra costs to go with foam would not have saved us more than $50 a month I'm sure. That's 15 yrs to pay out. I believe the choice to go with cellulose was the correct one for us. YMMV.

So roughly $5 per SF of floor space for the 40 X 40 attic foam insulation application. Our 2200 sf home would run $11,000 at that same cost factor. We had R-50 cellulose put in when we built our home at a cost of > $2,000. Our total electric home's utility costs per month have been under $150. That $9,000 extra costs to go with foam would not have saved us more than $50 a month I'm sure. That's 15 yrs to pay out. I believe the choice to go with cellulose was the correct one for us. YMMV.

How many folks live in your home, stick? Amazed to see total electric home of that size at < $150/mo, so wondering what other variables might be in play...

Just two of us here and I work at home part time in one of our attached garages which has 9 fluorescent lights and a 12,000 BTU mini split system heat pump. My shop also sees a lot of usage of a 2 stage industrial air compressor and several other industrial machines. Our water heat is a 50 gallon Geo Spring Heat pump unit which costs less than a gas water heater to operate. The outdoor HVAC unit is probably oversized at 5 tons but it's a 15 seer heat pump and the attic ductwork is insulated to R8.
Wall insulation is cellulose blown in behind netting fabric. We lived in a house half this size previously but the peak combined gas & electric bills were double what they have been here. ($300 a month in the hottest and coldest months)
I do like the idea of spray foam in the attic just for the convenience of being able to navigate around up there to run wires, etc but the cost payout wasn't workable for us since we're semi retired and the likelihood of being in this house for < 10 yrs is doubtful.

So roughly $5 per SF of floor space for the 40 X 40 attic foam insulation application. Our 2200 sf home would run $11,000 at that same cost factor. We had R-50 cellulose put in when we built our home at a cost of > $2,000. Our total electric home's utility costs per month have been under $150. That $9,000 extra costs to go with foam would not have saved us more than $50 a month I'm sure. That's 15 yrs to pay out. I believe the choice to go with cellulose was the correct one for us. YMMV.

Well, with the pitch of the roof, we actually had about 2300 sq ft of foam installed on the roof deck alone. I forgot that the $6K included foam for all rim joists between the basement and 1st floor and between 1st and 2nd floor. Our home is listed as 3000 square feet (our measurements indicate 2800 square feet).

We also paid another $2K for blow in insulation in all the existing walls, average about 5.5" thick since the home has 2x6 construction.