Winterizing a Denver Home: A Fall Checklist

Denver's weather can swing from a warm afternoon to a hard freeze overnight, and early-season snowstorms often hit while trees still have leaves. A few hours of fall maintenance prevents the classic winter calls: burst sprinkler lines, frozen hose bibs, ice dams and a furnace that quits on the first cold night.

Outside: water first

Blow out the sprinkler system. Water left in irrigation lines and backflow preventers can freeze and crack them. Most homeowners hire a sprinkler company to blow out the lines with compressed air before the first hard freeze. Schedule early, because companies book up when a cold snap is forecast. With Denver Water noting that drought recovery often takes multiple years, it's also a good time to fix leaks and broken heads so next season starts efficient.

Disconnect hoses. A hose left on a frost-free hose bib can trap water in the valve and burst it. Disconnect every hose, drain them and store them.

Shut off and drain older hose bibs. If your house has older, non-frost-free spigots, close the interior shutoff valve and open the outside spigot to drain it.

Clean gutters. Fall leaves plus early snow can quickly fill gutters and create ice dams. HomeGuide's gutter cleaning guide (updated November 7, 2025) puts professional cleaning at $100 to $250 on average, or $70 to $200 for a one-story home and $100 to $275 for two stories.

Check downspouts. Make sure they're connected and extended away from the house. Water dumped next to the foundation is bad any time of year on Front Range clay soils. See swelling soils and foundation care.

Look at the roof. From the ground with binoculars, look for missing or damaged shingles, especially after summer hail. Get repairs done before snow.

Ice dams

Ice dams form when heat escaping through the roof melts snow, and the water refreezes at the colder eaves. Water then backs up under shingles. The fixes are mostly in the attic: air sealing, insulation and ventilation. If you get one, HomeGuide's ice dam guide (updated October 17, 2025) says steam removal costs $800 to $2,400 and is the most effective method, while chipping costs $800 to $1,800. Don't chip ice with a hammer yourself; it damages shingles.

Homes in the foothills, like in Evergreen, get more snow and are more prone to ice dams.

Heating system

Furnaces. Replace the filter and schedule a tune-up before the season. HomeGuide's furnace cleaning guide (dated April 2024) lists basic cleaning at $70 to $100 and deep cleaning at $150 to $300. A technician should check the burners, flame sensor, heat exchanger and venting.

Heat pumps. Clear leaves and debris from around the outdoor unit and keep at least a couple of feet clear. In snow, keep the unit free of drifts, and make sure it's raised above where snow piles up. Don't block the defrost drainage. See our HVAC and heat pumps guide.

Water heaters. Check the venting on gas water heaters, and consider flushing sediment.

Safety

Carbon monoxide. Test CO alarms and replace batteries. Gas furnaces, water heaters, fireplaces and attached garages are all sources.

Radon. Winter, with windows closed, is a good time to test. CDPHE says about half of Colorado homes have radon above the EPA action level. See radon testing.

Smoke alarms. Test them while you're at it.

Windows and doors

Cold drafts around windows and doors waste energy. Replace worn weatherstripping and door sweeps, and caulk gaps in exterior trim. If your windows are failing (fogged glass, rotted sashes, broken balances), fall is a good time to get bids; see our windows guide. In historic districts, storm windows are often the best option.

Snow prep

• Have shovels and ice melt ready. Check whether your ice melt is safe for concrete and plants.
• Know your city's sidewalk snow removal rules. Many cities set deadlines for clearing sidewalks after a storm, and the rules differ between Denver and suburbs like Westminster and Thornton, so look yours up.
• Trim tree branches overhanging the roof or power lines before heavy, wet snow.