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I had my roof replaced last year and I am now seeing consistent temperatures in the attic that exceed 40 degrees over the outside temperature. For example, it was 62°F the other day and I had 108.5°F in the attic (house is in the northeast).

The attic surface is 26x22. Previously I had 3 box vents and small intake vents at about 6 feet intervals around the soffit and did not have this problem. The contractor installed a continuous soffit and a CertainTeed filtered ridge vent instead of box vents - the ridge vent is about 6 feet in length.

The exhaust seems a bit lower than before, but intake seems a lot more (I see daylight all around from inside the attic, so I assume that is all intake) so I am a bit baffled. By researching the only explanation I can think of is that there is now too much intake now and the system is unbalanced, creating high pressure in the attic and venting out from the intake rather than the ridge, with much lower performance.

The ridge is indeed small (roof looks squashed because of perspective):

as you can see from the picture

From inside the attic it measures 80 inches long and about 3 inches across. This is how the ridge looks from inside the attic:

ridge

And this is how soffit intake looks like (I removed the baffles to take the inside picture):

soffit outside

soffit intake

The ridge vent show daylight from the inside but I'd does look indeed a bit tight.

Does anyone have any insight? Should I install more exhaust? In this case, even if I installed box vents I would have to close the ridge vent not to mix exhaust types, right? Or close some of the intakes?

If I have 108 when it's 62 outside I am afraid of what is going to happen in the summer.

The total area of the attic is 572 sqft. It's a hip roof, so there is not much ridge, and the vent covers the whole ridge. I might have lowballed with 6 feet, but I'd say it's between 6 and 8 (the cut that I see inside the attic is 80 inches long)

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    6 feet of ridge vent really doesn't sound like much for a whole attic. I can't look for it now but you can find suggested intake/exhaust ratios for attic ventilation online. May 22, 2023 at 22:47
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    Was the roof colour changed to a darker colour/shade? Have you checked all vents are open and not blocked? Adding/increasing more exhaust vents should not mean to block existing vents. Just six feet does sound a bit low as the other comment suggested, more ridge or box vents would not hurt. My ridge vent is the full length of the roof.
    – crip659
    May 22, 2023 at 22:47
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    That sounds like way too little ridge vent. What's the total ridgeline length and the total roof area?
    – KMJ
    May 22, 2023 at 23:43
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    @crip659 Paint reflectivity is harsh - much below white it geos off a cliff. So not a lot of difference between gray and black. Unless OP's roof was very light before, it might be 80% absorption (anti-reflectivity) vs 95% aborption. But this can be researched. May 23, 2023 at 0:02
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    Seems more likely that there's blockage at the ridge vent. Can you inspect it from the inside?
    – Armand
    May 23, 2023 at 2:16

2 Answers 2

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Hip roofs are inherently challenging. The short length of the level ridge doesn't accommodate the area of the attic. While mixing vent strategies is generally not ideal, you have a few options to increase outflow (in addition to the ridge vent):

  • Find a ridge vent that claims compatibility with hip ridges.

  • Install box vents or turbines high on the less conspicuous hips and back side.

  • Install active ventilation, such as an exhaust fan on a thermostat.

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    Thanks for your reply. As I mentioned in the other comment I have a wireless thermometer sitting one inch above the attic floor to measure the temperature. At this point I will go back to the roofer and ask to install some box vents. I am a bit concerned of short circuiting by using turbines, but I guess that vents at almost at the same level of the ridge should not interfere with each other.
    – Marc
    May 25, 2023 at 0:25
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I see this all too frequently as a home inspector. Ridge vents only work if you have enough of them and they are long enough. Best option is to complement the ridge vent with 2 turbine vents placed as high as possible…the longer you wait the faster you shave the life off your new shingles as that high heat will shorten the life of even the best architectural shingle.

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