Winterizing a house is a short list done in the right order, not a long list done all at once. Seal and insulate the envelope first, because that is where the biggest energy savings sit. Then protect anything holding water outdoors or near an exterior wall, because a frozen or burst pipe costs far more than any amount of saved energy. After that, service the equipment that will run hardest for the next few months, and finish with the roof and gutters, which cause damage on a slower timeline. Most of this takes a weekend and costs less than a service call for the problem it prevents.
The checklist, ranked
| Priority | Task | Typical cost | What it’s worth |
|---|---|---|---|
| 1 | Seal air leaks around windows, doors, and penetrations | $20–50 in caulk/foam | Up to 20% off heating and cooling costs |
| 2 | Insulate the attic to local code level | $0 (DIY check) to $1,500+ (add insulation) | ~15% combined heating/cooling savings |
| 3 | Disconnect hoses, drain and insulate outdoor faucets | $10–20 in faucet covers | Avoids a burst pipe and a plumber bill |
| 4 | Insulate exposed pipes in crawl spaces and exterior walls | $15–40 in foam sleeves | Same, for pipes you can’t see |
| 5 | Replace the furnace filter and book an HVAC tune-up | $15–25 filter; $100–200 tune-up | Keeps the system from running inefficiently all season |
| 6 | Seal and insulate accessible ductwork | $50–150 in mastic/tape | Measured 14–16% heating-season savings in one study |
| 7 | Check the water heater and thermostat settings | $0, a few minutes | A few % off a bill that’s already paid for |
| 8 | Clear gutters and check attic insulation/ventilation | $0 DIY to $150 for a cleaning service | Prevents ice dams and roof/gutter damage |
The cost ranges are typical US retail and contractor pricing; your market will vary, but the order of priority holds almost everywhere.
Why seal and insulate before anything else?
Because it is the single biggest lever on a heating bill, and it’s also the cheapest. According to ENERGY STAR, a homeowner who seals air leaks and adds insulation to recommended levels can cut heating and cooling costs by up to 20%, and on average save around 15% on heating and cooling from air sealing plus attic and floor insulation together. Heating and cooling already make up close to half of a typical home’s energy use, so a 15–20% cut there moves the whole bill more than almost anything else on this list.
Start at the leaks you can feel: around window and door frames, where pipes and wiring pass through exterior walls, around recessed lighting, and at the attic hatch. A tube of exterior-grade caulk for trim and a can of expanding foam for larger gaps will handle most of a typical house. Weatherstripping — the compressible gasket kind for doors, the V-strip kind for windows — seals the parts that need to keep moving.
Insulation is the slower half of the job. Most US attics built before the 1990s have less insulation than current recommendations call for, and topping up a thin attic is one of the few home upgrades that keeps paying every winter and every summer after it’s done. If you’re not sure what’s up there, a flashlight and a tape measure in the attic hatch answers the question in five minutes: insulation that doesn’t fully cover the joists, or that you can see the tops of the joists through, is thinner than it should be.
How do you winterize outdoor faucets and pipes?
This is the step that prevents the most expensive single failure on the list: a frozen pipe that splits and floods a wall or ceiling once it thaws.
- Disconnect every hose. A hose left attached traps water in the faucet even on a “frost-free” model, defeating the design. University extension offices are consistent on this point: Oklahoma State Extension and the University of Illinois Extension both single out hoses left on outdoor faucets as a common, preventable cause of freeze damage.
- Shut off and drain. If the faucet has an interior shutoff valve, close it, then open the outdoor faucet to drain the remaining water and leave it open for winter.
- Cover or insulate faucets that aren’t frost-free. A foam faucet cover is a few dollars and takes seconds to fit.
- Insulate exposed pipes in crawl spaces, unheated basements, garages, and along exterior walls with foam pipe sleeves. These are the pipes most likely to freeze because they sit outside the home’s main heated envelope.
- On hard-freeze nights, let a faucet on an exposed exterior wall drip slightly and open cabinet doors under sinks on outside walls so household heat can reach the pipework — both are standard advice from UGA and Oklahoma State extension programs.
- Know where the main shutoff is. If a pipe does split, the first move is cutting the water supply, not finding a bucket.
Does the HVAC system need attention before winter?
Yes, and it’s the cheapest maintenance on the list relative to what a neglected system costs. A dirty filter forces the blower to work harder and can cut efficiency and shorten the equipment’s life, so replace it going into the heating season and then check it monthly during heavy use. Pair that with a professional tune-up before the system runs daily: a technician checks the heat exchanger, burner, and controls, catching problems while they’re a service call instead of a mid-January breakdown.
Ducts are worth a look if you can reach them in a basement or attic. Leaky, unsealed ducts running through unheated space waste conditioned air before it reaches a room at all. A Department of Energy–sponsored field study that compared utility bills before and after duct sealing measured about 14–16% heating-season savings, depending on the sealing method used — a real, independently measured range rather than a marketing number. Accessible duct joints and the connections at the furnace cabinet are the easiest places to start, sealed with mastic or metal-backed tape (ordinary cloth duct tape fails within a few years).
If you have ceiling fans, now is also when the winter-reverse question comes up. Ceiling fan direction covers the summer and winter settings in detail; the short version is that reversing a fan to push warm air down helps a little in a tall or vaulted room, but it’s a minor move compared with sealing and insulation.
What should the thermostat and water heater be set to?
Thermostat: the Department of Energy’s guidance is that setting it back 7–10°F for eight hours a day — overnight, or while the house is empty — can save as much as 10% a year on heating and cooling. The exception is a home with a heat pump: because of how heat pumps recover from a setback, DOE generally advises against the deep nightly setback that works well with a furnace or boiler, and a smaller, steadier setback suits them better. A programmable or smart thermostat makes the schedule automatic instead of relying on remembering to turn a dial.
Water heater: most households do best at 120°F (49°C), which balances standby energy loss against scald risk. What temperature should a water heater be set at covers the full trade-off, including when a higher setting is worth it for Legionella risk in a vulnerable household. If you want to see the thermostat or water heater change show up on a bill, read your electricity meter before and after to confirm it rather than guessing.
How do you prevent ice dams and gutter damage?
An ice dam forms when heat escaping into the attic melts snow on the upper roof; the meltwater runs down and refreezes at the cold eaves, building a ridge of ice that backs water up under the shingles. Extension engineers at North Dakota State University and the University of Minnesota agree on the underlying cause: too little attic insulation, too little attic ventilation, or both, letting the roof surface stay warmer than the outside air. NDSU’s guidance points to a combination of adequate insulation and balanced soffit-to-ridge ventilation as the fix, plus sealing the attic-floor penetrations — around plumbing stacks, electrical boxes, recessed lights, and the attic hatch — that let warm household air leak upward in the first place.
Gutters play a supporting role: a gutter packed with fall leaves holds water against the fascia and roof edge, and that water is the first to freeze when temperatures drop. Clearing them before the first freeze, and again after leaves finish falling, keeps meltwater moving off the roof instead of pooling at the edge. A roof rake used from the ground to clear snow near the eaves after a heavy fall is a reasonable short-term measure extension offices also mention, though it treats a symptom rather than the attic conditions causing it.
When should you start winterizing?
Before the first hard freeze in your area, not after. Air sealing, insulation, and HVAC service can happen any time it’s dry enough to work outside; outdoor faucets and exposed pipes need to be done before overnight temperatures first drop below freezing, since that’s exactly the failure they’re guarding against. Most of the US sees its first freeze somewhere between late September and early November, so starting the checklist in September or October leaves room to work through it without rushing the pipe and faucet steps at the last minute.
What’s the single best thing to do if you only have a weekend?
Seal and insulate. It’s the top two rows of the table above for a reason: it’s the largest percentage off the biggest line on the bill, it’s almost entirely DIY-able with a caulk gun and a trip to the hardware store, and unlike a furnace tune-up or duct sealing, there’s no equipment to schedule or technician to wait for. Everything else on the list protects against a specific failure or shaves a few more percent; sealing and insulating is the one that pays all winter regardless of what else gets done.