Why Wisconsin attics need this
Milwaukee in July averages 82°F. Madison runs about the same. Sounds tame. The attic above your kitchen does not care what the lawn thermometer says. Asphalt shingles on a sunny Wisconsin afternoon push the roof deck past 130°F, and the air trapped under it sits there cooking until well after dark. Lake Michigan air is wet by default, so the heat in your attic is humid heat. That is the heat that drives down through your ceiling drywall into the bedrooms and keeps the upstairs three to six degrees warmer than the thermostat reads. Your central AC runs longer to fight it. Your power bill picks up the tab.
Then it flips. November through March, Wisconsin attics turn into refrigerators with a moisture problem. Warm air from showers, cooking, and laundry rises through every can light and attic hatch into the cold attic space, hits the cold underside of the deck, and condenses. That condensation soaks the insulation, rots the sheathing nails, and freezes at the eaves where it forms ice dams. Most of the $3,000 to $7,000 ice-dam repair bills our installers see started as a venting problem in October, not a roofing problem in January.
A solar attic fan turns the attic air over whenever the sun is up. In July it dumps the cooking summer heat. On a bright winter afternoon it pulls the moist house-air out before it can freeze on the underside of the deck. The same fan does both jobs. It does them with sunlight. Your meter does not move.
What we install
One 30W solar attic fan with an integrated panel, mounted on the back slope where it is invisible from the street. Your authorized installer cuts the opening, flashes it for Wisconsin winter ice and meltwater, sets the thermostat and humidistat in the attic, and is back down the ladder in a single visit. No electrician. No conduit. No operating cost added to your bill.
What you'll save
The average Wisconsin home uses about 8,200 kWh per year. A typical July or August power bill runs about $130. Cooling-load savings from attic ventilation in this climate land at 10 to 18 percent, so figure $13 to $23 a month from June through September.
The bigger savings show up in the winter ledger. An ice-dam leak that runs through your master bedroom ceiling costs $3,000 to $7,000 once you add roofing, drywall, paint, and the insulation you have to throw away. A properly vented attic also keeps blown-in insulation lofted and dry, which is the difference between your furnace cycling normally and your furnace running constantly from January through March. Cooler, drier shingles last longer too. We see Wisconsin roofs come off at 18 to 20 years when they could have gone 25 to 28.
Real Wisconsin install scenarios
Bay View in Milwaukee. A 1912 bungalow with a finished half-story upstairs and only two small gable vents. The upstairs bedroom hit 88°F on July afternoons even with the window unit running. The installer added the solar fan on the back slope and opened up two blocked soffit bays. By the next week the bedroom held at the thermostat setting. The owner texted us a photo of the unit and said the only way she could see it was from her neighbor's second floor.
Near East Side in Madison. A 1930s Cape with a recent shingle replacement and a foam-sealed attic floor. Beautiful work, except the contractor sealed it so tight the attic had nowhere to dump moisture. The owner saw frost on the underside of the deck in February. We added the solar fan and a humidistat. The frost was gone within two bright winter afternoons and never came back.
Green Bay west side. A split-level from 1968 with composite shingles and original ridge vent. The owner had two winters of ice dams over the garage and one over the back bedroom. Diagnosis: ridge vent was undersized for the run of the roof and the attic was holding moisture all winter. We placed the fan on the back slope above the bedroom and ran a humidistat. The next winter brought 60 inches of snow and zero dam.
Installed by Wisconsin authorized installers
Wisconsin housing stock leans old in the cities and 1950 to 1980 in the suburbs. A lot of these homes have venting designs from before modern insulation made attic moisture an issue. Our installers know how to read the framing before they cut. Back-slope placement keeps the unit hidden from the street, which clears every Whitefish Bay and Shorewood historic guideline we have dealt with.
You pick a date, the installer shows up, and your attic stops cooking in July and stops freezing-sweating in February.
