Attic ventilation is one of the most effective ways to cool a home in Colorado, and it is also the thing Excel Roofing crews find done wrong more often than anything else on a roof.
There are three attic fan options worth considering for most homes: powered attic fans, solar powered attic fans, and gable fans. All three pull hot air out of the attic. They mount differently, they cost differently, and the right choice depends on the house.
Here is how each one works, what the controls actually do, and what a homeowner should expect to pay.
An attic without adequate ventilation traps heat in summer and moisture in winter.
That trapped heat radiates down through the ceiling into living space, which forces the air conditioner to work harder and drives cooling costs up. It also bakes the roof deck and the shingles from underneath, shortening the life of the entire roof system.
Trapped moisture causes a different kind of damage. It condenses, saturates insulation, and creates the conditions for mold and rot in a part of the house most homeowners never look at.
Moving air through the attic addresses both problems at once. It is one of the least expensive upgrades available and one of the highest impact.
Two problems show up again and again on Colorado homes.
The first is simple under-ventilation. The attic does not have enough exhaust capacity for its square footage, so hot air has nowhere to go.
The second is less obvious and more common than most homeowners expect. Too many types of ventilation end up combined on the same attic. When a roof carries ridge vents, box vents, turbines, and a powered fan all working the same space, those systems compete with each other instead of pulling air along a single path from intake to exhaust. The attic looks well vented from the driveway and performs poorly in practice.
Ventilation works as a system. Adding more of it is not the same as improving it.
The powered attic fan is the option Excel Roofing recommends most often. It mounts on the roof surface and runs on standard household current.
What makes it practical is the plug. Excel Roofing can run a cord up to 50 feet, so if the attic already has an available outlet, there is no need to bring in an electrician. That removes a line item and a scheduling headache from the project.
A powered attic fan is controlled by two settings that work independently.
The thermostat turns the fan on once the attic reaches a set temperature. Most units recommend somewhere between 100 and 110 degrees. Setting it closer to 95 or 100 degrees gets the fan working earlier in the day, before the attic has fully heat-soaked.
The humidistat is the control most homeowners overlook. It switches the fan on when attic humidity climbs past a chosen threshold, usually somewhere in the 30 to 40 percent range.
That humidity setting is what turns a powered attic fan from a summer appliance into a year-round one.
Showers, cooking, laundry, and ordinary daily activity put a significant amount of moisture into the air inside a house. That moisture rises through the ceiling and into the attic, where cold weather condenses it on the underside of the roof deck. A humidistat-equipped fan cycles on through the winter to exhaust it before it soaks insulation or damages sheathing.
A fan set on temperature alone sits idle for half the year, which is exactly when moisture is doing the most damage.
For a homeowner who would rather not involve electricity at all, the solar powered attic fan is the answer. A photovoltaic panel drives the motor, so the unit runs on sunlight. No cord, no outlet, no electrician.
It is also the quietest option by a wide margin. These units run whisper quiet, to the point that it is often impossible to tell from inside the house whether the fan is running.
The third option mounts in the gable end of the attic rather than on the roof surface, which means installing one does not require cutting a new hole in the top of the roof. For a homeowner with a newer roof, or one who simply does not want another penetration in it, that matters.
Gable fans also move the most air of the three. High-powered units exhaust between 1,500 and 2,500 cubic feet of air per minute. A cubic foot is roughly the volume of a balloon, so picture 1,500 or more balloons of hot air leaving the attic every minute.
The tradeoff is noise. Gable fans run louder than rooftop or solar units, which is worth considering depending on what sits below the gable. Excel Roofing's own founder, J Bretz, runs one over his garage for that reason.
General installed pricing runs as follows:
These are ballpark figures, not quotes. Attic access, roof pitch, existing wiring, and the condition of the current ventilation all move the number. An on-site estimate is the only way to get an exact price.
Installing a rooftop unit, powered or solar, during a roof replacement costs less than installing one on its own. The crew is already up there with the deck open, so the labor is largely absorbed into work that is happening anyway.
Gable fans work differently. Because they do not penetrate the roof surface, they can go in at any time and the price stays the same whether the roof is brand new or twenty years old. They simply start from a higher number.
A homeowner planning a roof replacement in the next year or two is better off bundling a rooftop fan into that project than paying for the access twice.
There is no single answer that fits every house. The decision usually comes down to a handful of practical questions:
One more factor matters before any of those: intake. Exhaust fans need air coming in at the soffits to work correctly, and a contractor who recommends a fan without evaluating intake ventilation is only solving half the problem.
Excel Roofing has been ventilating Colorado and Wyoming attics since 1993. A free on-site estimate covers what the attic has now, what it is missing, and which option makes sense for the house and the budget, with an exact price rather than a ballpark.
Call Excel Roofing directly or use the online scheduler to pick a day and time that works.
It depends on the attic. Powered attic fans offer thermostat and humidistat control for roughly $1,000 installed. Solar powered attic fans run whisper quiet with no electrical work required. Gable fans move the most air, between 1,500 and 2,500 cubic feet per minute, without cutting a hole in the roof. Excel Roofing recommends powered attic fans most often, but the right answer depends on attic access, existing wiring, noise tolerance, and whether the roof is being replaced.
Excel Roofing installs powered attic fans for approximately $1,000, with solar powered units priced comparably. Gable fans typically start around a couple thousand dollars and increase based on the work involved. Rooftop units cost less when installed during a roof replacement. An on-site estimate provides exact pricing.
Not always. A powered attic fan can be installed with a cord up to 50 feet long, so if the attic has an available outlet, no electrician is needed. Solar powered attic fans require no electrical connection at all, since a photovoltaic panel powers the motor.
Most powered attic fans recommend a thermostat setting between 100 and 110 degrees Fahrenheit, though setting it closer to 95 to 100 degrees starts the fan earlier in the day. The humidistat is typically set to trigger when attic humidity exceeds 30 to 40 percent.
Yes, when humidity calls for it. Moisture from showers, cooking, and laundry rises through the ceiling into the attic, where it condenses in cold weather. A humidistat-controlled fan cycles on to exhaust that moisture, which helps protect insulation and the roof deck.
Two mistakes come up most often. The attic is under-ventilated for its size, or too many different types of ventilation have been combined on the same attic. Mixing systems causes them to work against each other rather than moving air along one path from intake to exhaust.