re: My attic hit 150F today

I’ve given consideration a few times over the last 2-3 years between dealing and foam-insulation in the attic vs opening it up with more ventilation (whirley birds).


Pros on the foam:
Easily gain 2,000sqft of storage space that’s much more usable than current based on humidity control alone (which I don’t necessarily need, but it would be nice to have. My attic has two regular sized doors, so as the kids get older, the idea of storing off-season sports equipment, clothes, etc gets a little attractive. But I’m not exactly at the point where I have to have that space.
Presumably some cheaper cooling bills.
Cons:
I read about the potential for shingle damage and small leaks leading to big rot before they’re fixed. I’ve never had a leak in the first place. I don’t really know how common a leak leading to decking rot is or how big a difference the price in repair is if you ruin a sheet of plywood vs 3-4. Like, I mean, I get that it’s a bigger area and all. But this is 1 in 100? 1 in 10,000? 1 in 1,000,000? On top of that, the difference in repair price- are we moving from 1,000–>3,000? A patch job I can do in an afternoon to $15,000? I find no useful information on this.
I have gas water heaters and heat. So my attic will require “fresh air” vents which are basically just putting rigid duct from a soffit to the flames. Not terribly inconvenient. They add to the price, and you lose some “flat” space that could/will be decked to a vent running on the ground, but it doesn’t seem like a real terrible inconvenience
Got a variable AC unit upstairs already that we can kick/spin down for humidity control, but requires more expensive HVAC +/- a dehumidifier if that isn’t cutting it.


Anyone got insight with realistic expectations of why one should/shouldn’t go for encapsulation vs ventilation if the up-front cost isn’t a deterrent based on actual long term (20-30 year) impacts on home electric cost/savings vs roof repairs?

The cons of foam, and radiant barriers as well, is moisture building up and causing mildew and rot. Again, the right installer and experience is key along with the humid climate. Cellulose is an option though as it's more like R22. I've had R22 generously added to the base R22 insulation and have never had problems in heat or cold. In a previous house I had pipes in attic with R22 underneath, pipe rap and R22 laid over the top and didn't freeze when we were in the teens for a week. Tried and true techniques used since central a/c became popular in the 70s still works today. More energy is lost via windows and doors then anywhere. Especially with kids and animals going in and out all summer.
A properly sized and efficient HVAC install is important. If the CFMs are correctly calculated, then you never have to close a vent to redirect air, which by the way just builds up pressure and interrupts free air flow in the ductwork.

We got a new roof last summer. They removed our ridge vent and added whirley birds. My husband was in charge of that aspect of it.

We recently had more insulation blown into the attic as well. Our ac is maybe 7 years old and has zero issue keeping the house at 71.

Varies. Could just make your unit run longer to reach the desired temp which puts more wear on the unit. My neighbor could not get under 76 inside on a 95 degree day. He covered the ridge vents and put in 4 turbines and his a/c could get down to 70. His attic temp dropped 40 degrees. It depends on the age of the unit also.

Attic temp is one thing, but I’m curious who is testing their first floor ceiling temps before and after adding the turbines. That’s more directly tied to how much the AC is working. The attic can be as hot as it wants if it’s insulated well enough from the conditioned space. That and duct insulation.

Does turbine effectiveness depend on soffit vent acceptability, too?

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do you not have soffit vents?

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Just realized I do have soffit vents and a ridge vent (which is entirely too small for my massive attic). Roofer recommended 3 whirlybirds - advised against the electric or solar vents.

$325 each installed

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There is zero ventilation currently

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Sometimes the soffit vents get clogged and need to be cleaned, especially if they have bug screens on them. Normally you can just take an air compressor or pass by with the blower, but I’d suggest taking them off, washing them out, and see if it’s still an issue. This will also give you a chance to see if your hole was cut big enough.

Air in = air out, and it’s cheaper and easier to fix the in than the out.

We are currently in the same boat with our walk in attic. I really want to spray foam it but I do have some reservations. It is on the second floor. It houses our Christmas / seasonal stuff, luggage, etc.. It also has the first story A/C in there.

There are only soffits in this area. No ridges or whirly birds. It also wraps behind my son's room so it adds heat to his room. Really need to fix this and am leaning towards foam as I want to essentially make it a storage area while mitigating 125f of steaming heat.

Joe Foti @ Gauthiers Roofing
985-789-1504

Have used him for a few things and he is excellent