Serving Salt Lake City, UT & Nearby Areas
(385) 438-3591
Serving Salt Lake City, UT & Nearby Areas
(385) 438-3591
Because inspections don't measure ventilation. A city inspector checks the permitted scope; nobody runs the intake-and-exhaust math the code ratio requires. So an under-ventilated roof passes every day. About 90 of every 100 attics my crews get into are under-ventilated. Passing inspection means legal minimums got checked, not that the roof was done right.
Have the ventilation ratio actually measured: intake and exhaust, against your attic's square footage.
Code sets a required vent-area ratio, but inspections rarely test it, so failures pass unnoticed.
Ask for the intake and exhaust numbers at your next roof assessment.
A Utah inspection won't measure your attic's ventilation ratio. So ask for the numbers yourself: intake, exhaust, and the code math.
Mattie Tueller, Master Roofing
A city inspection verifies the work described on the permit: the covering, the visible code items, the scope that was declared. What it almost never includes is computing your attic's net free vent area against the ratio in IRC section R806, because that math takes measuring every intake and exhaust vent on the house.
Purchase-time home inspections have the same gap: a home inspector notes visible vents but almost never runs the ratio. So a roof can pass a city inspection and a sale inspection while its attic quietly fails the one number the code actually specifies.
The International Residential Code requires roughly 1 square foot of net free ventilating area for every 150 square feet of attic space, reducible to 1 per 300 when the venting is balanced between intake and exhaust. It is a real ratio with real math, not a judgment call.
Exhaust at the ridge only works when intake at the eaves feeds it. Air has to enter low and leave high; exhaust without intake just doesn't move air. Intake is also the expensive, unglamorous half, which is why bids quietly skip it. Intake ventilation is a real cost. It is a common reason one bid sits higher than another. We price the whole roof, ventilation included, where a lot of companies shortcut around it.
When a bid mentions ridge vent but says nothing about intake, the ratio is not being met. The attic will pass inspection anyway, and the attic will still be wrong.
Three forces stack up: nobody has to prove they know the math, many installers never learned it. Other trades undo what venting exists. Together they produce Mattie's field number: about 90 of every 100 Utah attics run under-ventilated.
None of those three ever meets an inspector with a calculator. That's how the failure persists at scale.
Measure first, then fix the balance. Under-ventilation is one of the most correctable problems in roofing. It rarely requires a new roof.
The stakes are bigger than comfort: wrong ventilation voids shingle manufacturer warranties. The symptoms (a hot upstairs, winter condensation, attic mold) each have their own stories in the attic ventilation cluster. The fix costs a fraction of what the symptoms eventually do.
Homeowners hear "your attic is under-ventilated" and push back with a reasonable fact: the roof passed inspection. I understand the frustration. You did everything right, pulled the permit, got the sign-off. Now a roofer is telling you the attic fails the one ratio the code actually spells out.
Here is the reconciliation: the inspection checked that the permitted work happened. It did not measure your intake and exhaust against your attic's square footage. That's because inspections almost never do. Building code is the bare minimum standard to stand up a structure. It's not the right way to do it. And in this case, even the bare minimum went unmeasured.
Master Roofing does the ratio on every bid, intake included. That line is missing from a lot of bids, which is part of why the numbers do not match. Ask every bidder for the same math. The paperwork protected the process; the numbers protect you.
Building codes, permit rules, and licensing requirements change over time, and they differ by city and county across Utah. Verify current requirements with your local building department before relying on anything here, and work with a licensed contractor who knows the rules in your jurisdiction.
This article is general information about Utah roofs, not an assessment of yours. Every roof is different, and no article can tell you what is actually happening on your specific house. Have a licensed roofing contractor look at it in person before you act on anything here.
An upstairs that will not cool down after sundown, an air conditioner that runs all day and loses anyway, winter condensation in the attic where every nail drips, mold on the underside of the sheathing. Shingles aging from beneath. Most homeowners meet the symptom first and the diagnosis much later, usually from a roofer, not an inspector.
Usually not, because standard home inspections are visual: the inspector notes that vents exist, not whether their net free area meets the ratio for that attic's square footage. If you are buying, ask explicitly for intake and exhaust measurements, or bring in a roofing assessment that runs the actual numbers before you close.
No. Most corrections retrofit onto the existing roof: clearing buried eave vents, adding intake. Balancing exhaust at the ridge. A re-roof is the ideal moment to get the system perfect. But you do not have to wait for one. The measurement tells you how far off the attic is. The fix is scoped from there.
Yes. Shingle manufacturers require code-compliant ventilation. A wrong ratio gives them grounds to deny a claim on shingles that failed early from heat. The homeowner rarely learns this until the claim moment. That's what makes ventilation the quietest expensive problem in roofing. Getting the ratio measured protects the warranty you already paid for.
The roofer designing the system. Ventilation math belongs in the bid: attic square footage, intake area, exhaust area. What gets added to close any gap. Ask every bidder for those numbers. A bid that includes ridge vent but never mentions intake is a bid that skipped a code item. The inspection will not catch it later.
We're here to see what's going on with your roof. A real assessment starts with your history and your attic, not a number from the driveway. You'll get a straight answer about what's up there, what it needs, and what it costs. Sometimes the honest answer is: your roof looks great.