Attic ventilation in Phoenix area homes ? (Yuma: sales, how much, crawl space)

[veritased]

Thanks everyone !

FarmerLarry, do you recall if it made any difference ? I would just pay someone to do it... our roofline is probably approx the 5 ft from ceiling to ridge, but still I am taller and not made for tunnel rat mode.

DougStark, I tend to agree. I just looked at a satellite image of the house (I'm still in CA) and there are no such ridge vents in place, so I'd have to cut one in, and I am sure these things would fail in no time, then I'd have to replace it, the hole would be different, such a hassle. I agree about sealing the ceiling, that I will do myself before we move everything in.

Zippyman, thanks for that data! Do you know if your attic had soffit vents and a ridge vent by any chance ?
Do most of your houses out there have soffit/ridge vents ?

[Farmer Larry]

[quote=veritased;54387416]Thanks everyone !

FarmerLarry, do you recall if it made any difference ? I would just pay someone to do it... our roofline is probably approx the 5 ft from ceiling to ridge, but still I am taller and not made for tunnel rat mode.


Yes the added insulation made a big difference, the original insulation had settled down so much that I could see an inch or two of my ceiling joists in half of the attic so I only had an inch or so in many areas. I only blew in enough to make it 8 to 10 inches. If you have wires and boxes in your attic you might want to spray paint a mark on the roof above these areas before everything is hidden under insulation. I ran pex through the attic and that area has a bunch of warnings on the roof and on top of the insulation. You want to be careful where you step.


My neighbor with the same floor plan I mentioned earlier in this thread has his AC and heat running MUCH more than mine, he has no attic fan and I don't believe his attic insulation was ever added to after being built. I hear his unit cycling weeks before I even think of running mine in the spring and fall. We usually have a month or two in spring and fall when no heat or AC is needed.

[veritased]

Thanks Larry, quick question, having gone back to reread your posts.

You have an attic fan, saw that, and when it is running, where are the vents into that attic space ?
Soffit vents or other ?

Thanks.

[Farmer Larry]

Originally Posted by veritased

Thanks Larry, quick question, having gone back to reread your posts.

You have an attic fan, saw that, and when it is running, where are the vents into that attic space ?
Soffit vents or other ?

Thanks.

The fan blows out the north gable vent and the south gable vent is the main intake, there is a smaller gable vent on the back of the house facing east.

[veritased]

Thanks for that info, Farmer Larry.

[Zippyman]

Originally Posted by veritased

Thanks everyone !

Zippyman, thanks for that data! Do you know if your attic had soffit vents and a ridge vent by any chance ?
Do most of your houses out there have soffit/ridge vents ?

I had gable vents - personally, I think this is a desert/non desert question, I haven't seen any evidence that there really is the scrupulous need for soffit vents as you might require in different climates. I added ridge vents to my rentals when the shingles were replaced - there were crude soffit-vents in place on those (every third truss or so had a couple holes drilled with some screen over it) - I don't think they worked that well or did much, except provide entry for critters if they weren't scrupulously checked.



I'm also not sold on any kind of "power vent" solution or radiant barrier solution- your attic is just going to be 150+ degrees in the summertime, no matter how well vented it is. If there's enough attic insulation, that won't matter. there were some DOE studies done on houses with no insulation at all that showed it did help, but there hasn't been one to my knowledge that showed any benefit to radiant barrier in a properly insulated attic. Pretty much the same deal with "power vent" systems - if there's inadequate insulation, it'll kinda-sorta help, a little, in the "swing" months when there's a huge difference between nighttime & daytime temps, but otherwise it's mostly a wallet-lightener sold by charlatans to make a quick buck.



If I started over tomorrow with a new/older phoenix home & wanted to make a big dent in energy bills- I'd make sure to have at least 10" of cellulose in the attic - not for "r-value", but for air leakage + a properly sized A/C (probably at least 1/2 ton smaller than whatever was currently installed) - with a two-speed compressor - at the same time I'd add a second air "filter grill" for adequate return air, then I'd pop in a "heat pump" electric water heater - those things all made a huge difference in my bills & comfort. I don't think anything else pays you back the install cost in a reasonable amount of time.

[DougStark]

^^^^ I agree on most of your points, but as far as a radiant barrier, in this inferno summer climate, I suspect one is very effective at stopping infrared heat (invisible) coming from the roof through the attic insulation, and onto the drywall ceiling.

[DougStark]

VERITASED, no offense but you are OVERTHINKING and obsessing over this topic. I can get into the same thought pattern, but step back and don't micro-analyse this issue so much.

[Hal Roach]

A gone else seen the drywall with the radiant barrier built in?

[veritased]

Doug just trying to get to the optimal solution !