Attic Ventilation
Attic Ventilation in St. Louis, MO
Balanced intake and exhaust — the system most roofs get wrong.
The Situation
Ventilation is the most consequential part of a roof system that almost nobody discusses at the kitchen table. A roof with exhaust but no intake does not breathe. The attic runs hot in July and holds moisture in January, and the result is curled shingles well before their rated life, ice damming along the eaves, mold on the underside of the deck, and — the part that stings — a voided manufacturer warranty, because nearly every shingle warranty is conditioned on code-compliant ventilation.
What's Included in Every Attic Ventilation Job
- Attic inspection for moisture, mold, and heat signature
- Net free vent area calculation against attic square footage
- Intake versus exhaust balance assessment
- Ridge vent installation with a properly cut slot
- Soffit and edge intake vent installation or clearing
- Removal of conflicting exhaust that short-circuits airflow
- Bathroom and kitchen exhaust rerouted out of the attic where needed
- Baffle installation to keep insulation out of the intake path
Materials & Brands
We size ventilation to the attic rather than defaulting to one product. Continuous ridge vent is the standard answer on most St. Louis homes because it exhausts along the entire peak where heat actually collects. Box vents remain the right choice on roofs with short or broken ridge lines, and powered vents have a narrow set of legitimate applications — usually low-ridge or complex-geometry roofs where passive exhaust cannot achieve the required net free area.
How It Works
Our Attic Ventilation Process
- STEP 01
Get in the attic
You cannot assess ventilation from the ground or from the roof. We go inside and look for the evidence: rusted nail tips, dark staining on the deck, compressed or wet insulation, daylight where there should be intake.
- STEP 02
Run the numbers
We calculate required net free vent area against your attic square footage and compare it to what is actually installed.
- STEP 03
Balance intake and exhaust
Exhaust without intake pulls conditioned air out of your house instead of air out of your attic. Balancing the system is the whole job.
- STEP 04
Install and verify
We cut the ridge slot to spec, install intake, remove anything that short-circuits the airflow path, and document the finished system.
St. Louis & St. Charles Specifics
Why Attic Ventilation Is Different in Greater St. Louis
St. Louis attics fail from both directions. Summer attic temperatures here routinely exceed 140 degrees, which cooks shingles from underneath and drives cooling costs up through the ceiling plane. Winter brings the opposite problem: warm moist air from the living space condenses on cold decking, and on north-facing slopes that same trapped heat melts snow that refreezes at the colder eave and forms an ice dam that pushes water backward under the shingles. Both failure modes have the same root cause and the same fix. Flashing note: replacing flashing at every wall, chimney, and penetration is standard on every roof we install. It is not a separate service and it is not an upsell line item.
Questions
Attic Ventilation FAQ
It depends on whether you need exhaust, intake, or both, and on whether it is installed during a roof replacement or as standalone work. Adding ridge vent during a replacement is a modest incremental cost. Retrofitting soffit intake on a home that never had it is more involved. We give you a written number after we have been in the attic.
Yes, and this is widely underappreciated. Major manufacturers condition their warranty coverage on ventilation meeting code-required net free area. If your attic is under-ventilated and your shingles fail early, a warranty claim can be denied on that basis.
Usually not. A correctly balanced passive system with continuous ridge exhaust and adequate soffit intake outperforms a powered fan on most homes, and a powered fan installed without sufficient intake will pull conditioned air out of your living space. Powered vents make sense on specific roof geometries, and we will tell you if yours is one of them.
Common signs: rooms directly under the attic that never cool down, ice forming along the eaves in winter, a musty smell in the attic, visible dark staining or rust on nail tips through the deck, and shingles curling or losing granules well before their rated life.
Recent Work
Attic Ventilation Projects
Free, No-Pressure Inspection
Find out what you're actually dealing with
We get on the roof, document every slope, and hand you the photos — whether or not you hire us.