Attic temp fix

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Brought attic temp from 158 to 112

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I did similar a few years ago, then read up on ventilating the attic and now feel like I screwed up.

I suspect that creating proper soffit vent circulation was a much bigger (and cheaper) factor than the power vents.

Really brief synopsis from what I gathered.

If a hot attic is getting into a living space, then moving air out of that hot attic is just pulling in the cool air from the living space.

Now, with the OP and increasing air flow from the soffits there might be some advantage.

My house is around the 100+ range as well and I added a vent and increased air flow down the entire length. My goal was reduction of humidity with side quest of lower attic temp (thus lower a/c).

The suggestions I saw mostly were heat proof your living space from above rather than removing the heat from the attic.


After about $1000 in effort I only realized I have no idea what to do.

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I suspect that creating proper soffit vent circulation was a much bigger (and cheaper) factor than the power vents.

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Natural circulation using just convection through the sofit vents is better over the long term. Power venting will lift dust, and dirt bringing it into the attic eventually clogging sofet vent holes, and look really dirty. Natural convection does not move fast enough to lift dust, and dirt.

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If a hot attic is getting into a living space, then moving air out of that hot attic is just pulling in the cool air from the living space.

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In thermodynamics you have to think terms of movement of heat. Heat moves from warmer areas to cooler areas, not the other way You insulate the space between the attic and living space to reduce the speed of travel of heat from the attic to the living space. Lowering the attic temperature reduces the amount of heat that can transfer to the living space below. In the winter it works in the opposite direction, you are trying to reduce the movement of heat from the living space to the attic. Sealing up the attic and keeping it warmer will slow heat loss from the living space. In Summary, there is no such thing as “cold” it is just the absence of heat, heat moves from hot areas to cold areas, this is true for air, water, solid materials, etc,

My old house had really hot attic issues.

It got 135 degrees on days when it was 95 outside. The ductwork would struggle to bring cool air into the house so the a/c would stay on all day and rarely get below 74 degrees during the day.

We had attic fans on the north and south end of the house but they kept burning out. We never replaced them.

I never found a solution to the issue

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My old house had really hot attic issues. It got 135 degrees on days when it was 95 outside. The ductwork would struggle to bring cool air into the house so the a/c would stay on all day and rarely get below 74 degrees during the day. We had attic fans on the north and south end of the house but they kept burning out. We never replaced them. I never found a solution to the issue

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I know you don’t live there anymore, but that’s pretty normal in an older home and doesn’t (didn’t) indicate an issue (except your attic fans repeatedly burning out).

My house has more than adequate passive ventilation with soffit and ridge vent area exceeding recommended building standards and attic temperature will top out at 133 F on 95 F day outside. And a HVAC maintaining a temp of 74 F and running most of the day under those conditions suggest you had a properly sized HVAC unit.

I have considered adding a radiant barrier to the attic though to help lower attic temps on extreme summer days.

But good job OP on your project, I also agree opening your soffits was likely the main determining factor in attic temperature improvement. I’m assuming powered attic ventilation is your only method of removing heat from the attic and you don’t have passive ridge vents.

When we got a new roof, they removed our power vent and installed a ridge vent. I never measured the temp to compare, but it seems to be less than 158 degrees.

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After about $1000 in effort I only realized I have no idea what to do.

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Air seal the attic.
TLDR:

I just inherited and will be moving into the family home. I had inspector come take a look. Ducts need to be hung off of floor, insulation might be r18, bathrooms vent into attic. So I have been spending lots of quality time up there poking around.

On 2 of the ac vents I found 1/2 inch or greater gaps, so I spray foamed around all of them, the cellulose is discolored around it by the way. In the air return I could put insulation near the crack and it would suck it in, I foamed all of that, started doing all of the electrical, gas and other penetrations it is a chore, but now getting too hot, so it may have to wait till November to be completed. I will also need to get one of the guns for the foam the straw is a mess.

So I hope even that will help but plan to do more when it cools off. There is a 1980's vent fan on the gable I replaced belt but have also considered a solar unit.

In the MIL suite in back yard, I hung those ducts, getting rid of sharp turns in them and the output does seem to be greater.

I'm done typing.