Janesville Premium Roofing provides professional roof ventilation in Janesville, WI for residential and commercial properties across south central Wisconsin. Attic ventilation is governed by a different chapter of the Uniform Dwelling Code than the roof is, and that chapter took effect on a different day. SPS 322 became effective December 1, 1978. The roof chapter did not follow until June 1, 1980, a full eighteen months later.
That gap is real and it lands on Janesville houses finished in 1979. Those homes fall under the energy chapter's ventilation rules while sitting entirely outside the chapter that governs their roof covering. We have quoted houses on one block where one attic carries an obligation the next one does not, purely on the date the certificate of occupancy was issued. Eighteen months of drafting time is now a permanent line through this city's housing.
The requirement itself is arithmetic. SPS 322.39 sets the total net free ventilating area as a fraction of the ceiling area, either 1/150 or 1/300 depending on how the venting is split between high and low. At least half of that area has to sit high on the roof with the remainder distributed low, and insulation may not block the free flow of air. Both halves have to be present or the arithmetic means nothing.
Post-1978 houses were built to that math, at least on paper. Older Janesville houses in the Look West and Old Fourth Ward neighborhoods frequently have no soffit intake at all, gable vents doing the entire job, and a bath fan discharging straight into the attic space. None of that is a violation on those houses. It is simply how they were built. It just is not very good, and knowing which one you have matters.
Which changes what we recommend. On a 1979 or later house with failing ventilation we can point at a requirement, and the fix is usually restoring what was intended: pulling packed insulation off the eaves, adding baffles, opening soffit panels somebody painted shut. On a 1948 house we are proposing something new, so we price it as an optional improvement rather than a correction.
We measure before we sell anything. Net free area of the existing intake and exhaust, ceiling area by section, and a look at the underside of the sheathing for staining around the fastener tips. If the numbers already balance we say so and add nothing. Selling a ridge vent to a house that does not need one is easy money and a worse roof.
Our licensed and insured team brings the right materials and equipment to every job — No. 15 asphalt-impregnated felt underlayment, ASTM D4869 Type I underlayment felt, ring-shank nails set into 1x6 board sheathing, No. 28 gauge open-valley sheet metal, 50-pound roll roofing in closed valleys, step flashing and masonry chimney crickets — and backs the work with a written workmanship warranty. We serve Janesville and nearby communities including Beloit, Edgerton, Milton, Evansville.
What We Handle
Everything our roof ventilation in Janesville covers
One crew, one point of contact, and the full range of roof ventilation work in Janesville, WI. If it is on this list we do it in house rather than handing it to a subcontractor:
- roof ventilation Janesville
- attic ventilation requirements
- ridge vent installation
- soffit intake vents
- net free ventilating area
- attic baffles
- gable vent conversion
- bath fan venting
- attic moisture staining
- balanced attic ventilation
Not sure which one describes your situation? Describe it in plain words and we will sort it out — or browse the rest of our Janesville services.
Materials, equipment and how we do roof ventilation
The difference between roof ventilation that lasts and roof ventilation that gets redone in three years is almost always preparation and materials, not the finish you see on day one. We work with No. 15 asphalt-impregnated felt underlayment, ASTM D4869 Type I underlayment felt, ring-shank nails set into 1x6 board sheathing, No. 28 gauge open-valley sheet metal, spec them to the job instead of to the invoice, and write the material grades into the free estimate so you know exactly what you are buying.
Every Janesville job runs the same way: site walk and measurements, written scope and fixed price, protection of the surrounding area, then the work itself with a daily clean-up. Years of roofing work in south central Wisconsin means we have already met whatever your property is going to throw at us — awkward access, older construction, an HOA with opinions.
Where we do roof ventilation outside Janesville
Janesville Premium Roofing covers Janesville and the surrounding communities of south central Wisconsin. Crews run out to the same nearby cities every week, so an out-of-town job does not mean an out-of-town price.
- Roof Ventilation in Beloit, WI — Rock County, population 36,657
- Roof Ventilation in Edgerton, WI — Rock County, population 5,945
- Roof Ventilation in Milton, WI — Rock County, population 5,716
- Roof Ventilation in Evansville, WI — Rock County, population 5,703
- Roof Ventilation in Clinton, WI — Rock County, population 2,221
- Roof Ventilation in Orfordville, WI — Rock County, population 1,473
Start on the Janesville Premium Roofing homepage for a free estimate, or call (844) 511-2320 and describe the job.
Why Janesville Chooses Janesville Premium Roofing
- ✓We pull the assessor's construction year before we price a roof, because June 1, 1980 decides whether the state code governs your reroof or your contract has to.
- ✓Our estimates name specifications rather than adjectives: No. 15 felt or a labeled ASTM D226 Type I synthetic, four fasteners per strip shingle, a two-inch head lap.
- ✓We count existing layers by lifting shingles at the rake and a valley, and the count goes in writing before anything is sent to your insurance carrier.
- ✓We go in the attic on every inspection. Fastener rust, valley staining and packed eaves show on the underside of the sheathing long before they show on top.
The standards behind roof ventilation
Quality here is not a matter of opinion — it is written down. The roof ventilation work we do in Janesville follows published industry standards: NRCA publishes the Roofing Manual, the industry's reference for details and slope minimums, and Asphalt Roofing Manufacturers Association sets the shingle application and ventilation guidance the warranties reference. If a contractor cannot tell you which standard a detail comes from, that is worth asking about before you sign.
Every roof ventilation project in Janesville gets the same attention, whether it is a single room or a full commercial job. We show up on schedule, keep the site clean, and stand behind the work — the estimate is free and there is no pressure.
Ready to get started? Call (844) 511-2320 for a free roof ventilation free estimate in Janesville, or request a quote and we'll get right back to you.