Because insulation only does one job: it slows heat that is conducting through a solid surface. If air is moving in and out of your house, or the heat is being made or delivered inefficiently, the R-value printed on the label in your attic is almost irrelevant to what you are paying.
We get this call every January. Someone has R-38 blown in the attic, a bill that went up and stayed up, and a reasonable suspicion they were sold something that does not work. Usually they were not cheated. The insulation is doing exactly what insulation does, and the money is leaving through something else.
Below is the list, roughly in the order we actually find it. Read it in order, because the first two are the cause far more often than the last five, and several of the items on this page are not work we sell.
The short version
Heat leaves a house three ways: it conducts through surfaces, it rides out on moving air, and it gets wasted before it ever reaches you by the equipment making and delivering it. Insulation only addresses the first one. Air leakage, duct loss, and the heating system itself are where most surprising bills actually come from.
1. Air leakage. This is the usual answer.
A house is not a sealed box. Warm air rises, finds gaps at the top, and leaves, which pulls cold air in through gaps at the bottom to replace it. Building science calls it the stack effect. In a two-story Seattle Craftsman with a vented attic above and a vented crawl space below, the house is basically a chimney with furniture in it. The leaks that matter are not the ones you feel standing in the living room. They are at the top and the bottom.
The attic bypasses
Every hole that passes through your ceiling into the attic is a bypass: the gap around the bathroom fan housing, the plumbing vent stack, the top plates of interior walls, the chase where the flue or ductwork runs up, recessed can lights, the attic hatch itself. Most attics we open in this region have never had any of them sealed. The insulation was simply laid down on top.
That matters more than people expect, because blown-in and batt insulation are air permeable. Warm air moves straight through them. You can pile twenty inches of fiberglass over an unsealed ceiling and still lose heat up the same holes as before. This is the single most common gap between “the label says R-49” and “the house feels like R-15.”
The crawl space
Under the floor, the failure is different. A vented crawl space with open foundation vents is at outdoor temperature all winter. Cold air pushes in through the vents, through the rim joist gaps, around the plumbing and wiring penetrations, and up into the floor cavity. If the batts under your floor are sagging, fallen, or damp, there is nothing between a 38 degree crawl space and your kitchen floor but plywood.
This is why the cold-floor complaint and the high-bill complaint are usually the same complaint. See crawl space insulation for what actually fixes it.
Why R-value underdelivers on a leaky house
R-value is measured in a lab on a flat sample with no air moving through it. Your house is not a lab. Real installed performance depends on air sealing, full coverage with no gaps, and the insulation staying dry and at its designed thickness. A leaky assembly does not deliver its rated number, and no amount of extra depth fixes that. Sealing the plane first is what makes the insulation you already paid for start working, which is the entire argument for air sealing. It is usually the cheapest line item on any estimate we write.
2. The insulation is there, but it is not doing anything
The second most common finding. Insulation is present, visible, and reassuring, and it has quietly stopped working. What we look for:
- Settled. Blown-in loses depth over decades. What was installed at 14 inches in 1988 may be 8 inches now, and depth is the whole product.
- Compressed. Batts stuffed behind wiring, squashed under stored boxes, or jammed into a cavity too small for them. Compressed insulation loses a large share of its rating.
- Gapped. Batts cut short, pushed aside by someone running a cable, or missing entirely over a soffit or a dropped ceiling. A small gap costs far more than its share of the area, because heat concentrates through it.
- Wet. This is a Puget Sound special. A roof leak, a bathroom fan venting into the attic instead of outside, or crawl space ground moisture. Wet fiberglass is close to worthless and it does not recover.
- Rodent damaged. Also very common here. Tunnels, nests, and contamination. Rodents flatten the insulation where they travel and they travel along the warm routes, which are exactly the routes you needed insulated.
- Installed over an unsealed ceiling. The problem in section one. Correct product, correct depth, laid over a plane full of open holes.
If two or three of those are true in your attic, adding more on top of it is throwing good money after bad. That is what insulation replacement exists for: take the failed material out, fix what caused the failure, seal the plane, then insulate.
3. Your ducts leak, and they run through the cold
If you have forced air, the heat has to travel from the furnace or air handler to the rooms. In a great many Seattle-area houses those ducts run through the vented attic or the vented crawl space, which means every foot of that run is passing through outdoor air.
Two things go wrong. Ducts leak at the joints, so a share of the heated air never arrives in a room at all. And uninsulated or poorly insulated duct sitting in a cold crawl space sheds heat the whole way. You pay to make that heat either way.
Symptoms worth noticing: one or two rooms that never get warm no matter what the thermostat says, weak airflow at the farthest registers, dusty air, and a furnace that runs a very long time to move the house a couple of degrees. Duct sealing and duct insulation are HVAC work. We do not do it, and if that is what your house needs we will tell you so and get out of the way.
4. The heating system itself
This is the category people check last, and it is the one that produces the most dramatic bills. None of it is insulation work.
A heat pump running on backup resistance strips
If you have a heat pump and an electric bill that tripled in December, start here before you call anyone about insulation. Heat pumps move heat, which is efficient. The backup resistance strips inside the air handler make heat the way a toaster does, which is not. A heat pump in our mild winters normally delivers several times more heat per unit of electricity than the strips do.
The strips are supposed to come on briefly during defrost cycles and in genuinely cold snaps. When something is wrong, they run constantly: a bad outdoor sensor, low refrigerant charge, a failed reversing valve, a thermostat set up incorrectly, “emergency heat” left switched on by a previous occupant, or a big thermostat setback that makes the system call for auxiliary heat every morning. On a Seattle City Light all-electric house this is the most expensive single fault we see, and homeowners frequently mistake it for an insulation problem. It is not. It is an HVAC service call, and it is often a cheap fix.
Oversized, failing, or simply old
An oversized furnace short cycles: it blasts, satisfies the thermostat near the sensor, shuts off, and never runs long enough to heat the house evenly. Combustion equipment loses efficiency as it ages and as it goes out of adjustment. A gas furnace past roughly its expected service life is worth having evaluated on its own terms. And a surprising number of “high bill” calls come down to a thermostat that is mis-wired, mis-programmed, mis-located over a heat source, or running a schedule nobody in the house wants.
5. Windows and doors, the thing everybody blames first
Homeowners almost always name the windows. You can feel cold coming off the glass when you sit next to it, so the windows feel like the villain. On most houses they are not the biggest cause. Glass is a modest share of your total exterior surface compared with the ceiling, the floor, and the walls, and the ceiling plane above a leaky attic typically moves far more heat than the windows do.
Here is the part that costs us nothing to say and probably saves you a lot: whole-house window replacement is generally a poor investment judged purely on energy payback. It is one of the most expensive things you can do to a house, and on straight fuel savings it usually takes a very long time to return. Sealing and insulating the attic, the crawl space, and the ducts almost always buys more comfort per dollar.
Replace windows because they are rotten, because they do not operate, because the seals have failed and they fog permanently, or because you want them. Those are all good reasons. Just do not expect the bill to be the reason it pencils. Weatherstripping a leaky door and caulking window trim, on the other hand, is cheap, is often a weekend of your own time, and does help.
6. Rates and the weather year
This explains more bill increases than anyone wants to believe, and it is worth ruling out before you spend a dollar on the house. Two things changed that have nothing to do with your insulation: the rate you pay per unit of energy, and how cold the winter actually was. A cold stretch moves a heating bill substantially, and comparing this January against last November tells you nothing, because they are different weather.
The fix is to compare like with like. Look at your usage, in kWh or therms, not the dollar total, for the same month in consecutive years. Then check those months against heating degree days, which are published by the National Weather Service and are simply a measure of how much heating weather a period contained. If your usage per heating degree day is flat year over year, your house did not get worse. Your rate went up or the weather got colder, and no contractor can sell you a fix for that.
7. Everything else on the same bill
In an all-electric house the heat shares the bill with everything else, and a new load looks exactly like a heating problem on the statement. Before blaming the envelope, account for the water heater (especially a failed element or a leaking hot water line, which can run continuously), an EV charging at home, a hot tub, a second refrigerator or freezer in the garage, a new dryer, or a space heater someone has quietly been running all winter in one cold room. That last one is worth checking honestly. Portable electric heaters are expensive to run, and they usually turn up in exactly the room that has the real insulation problem.
How to diagnose this yourself, in an afternoon
Pull the usage history
Log into your PSE or Seattle City Light account and look at usage, not dollars, month by month across at least two years. Find the month the change started.
Check it against the weather
Compare the same months year over year against heating degree days. If usage per degree day held steady, the house is fine and the change is rate or weather.
Go look in the attic and the crawl space
Bring a flashlight. Measure the depth of the insulation with a ruler. Look for daylight, gaps, flattened tracks, staining, and damp.
Watch the system run
Note how long it runs and whether it ever really stops. On a heat pump, find out whether auxiliary or emergency heat is engaging, and how often.
A few more checks that cost nothing. On a cold windy evening, walk the house with the back of your hand near the floor along exterior walls, at outlets, at the attic hatch, and at the top of the stairs. Close a door on a dollar bill and see if it pulls out freely. Stand in the room that is never comfortable and work out whether it is a cold surface problem, a no-airflow problem, or both. And while you are in the attic, confirm the bathroom fan duct actually leaves the building.
Symptom to likely cause
| What you notice | Most likely cause | Who fixes it |
|---|---|---|
| Cold floors, worse in winter, whole first level | Crawl space: vented, leaky rim joist, fallen or wet batts | Insulation contractor |
| Upstairs cold, downstairs fine, bills high | Attic bypasses and settled or gapped attic insulation | Insulation contractor |
| One or two rooms never get warm, weak airflow | Duct leakage, disconnected duct, or a balance problem | HVAC contractor |
| Electric bill doubled or tripled in one cold month | Heat pump running backup resistance strips | HVAC contractor |
| Furnace runs in short bursts and the house stays uneven | Oversized or short cycling equipment, thermostat placement | HVAC contractor |
| Drafts you can feel at outlets and baseboards | Air leakage through the wall and floor assemblies | Insulation contractor |
| Bill rose but usage per heating degree day did not | Rate change or a colder winter | Nobody. Nothing is broken. |
| Bill rose in a mild month too | A non-heating load: water heater, EV, hot tub, appliance | You, or an electrician |
What we will and will not take on
We are a spray foam insulation company. Air sealing, attic insulation, crawl space insulation, wall insulation, and replacing failed insulation is our work. Ducts, furnaces, heat pumps, thermostats, refrigerant, wiring, and water heaters are not. We are not licensed to touch most of it and we will not pretend otherwise.
So if Paul comes out, looks at your house, and finds your heat pump has been running on backup strips since a technician left a setting wrong two winters ago, you are going to hear that instead of a quote. Same if the real problem is duct leakage in the crawl space, or a roof leak that has to be fixed before anything else happens. Selling foam to a house whose problem sits upstream of the insulation just means taking your money and leaving the bill where it was, and then it is our name on the job that did not work.
Plenty of houses do have a real insulation and air leakage problem, and in those houses this work genuinely moves the number. We just will not tell you what that number is before we have seen the house. Read how much spray foam can actually cut your energy bill for why we refuse to quote a percentage, and whether spray foam is worth it in Seattle for when it is and is not the right call.
Common questions about high heating bills
I added attic insulation last year and my bill did not change. What went wrong?
Most often the ceiling plane underneath was never air sealed, so warm air still moves through the same penetrations it always did: fan housings, wall top plates, the flue chase, the attic hatch. Blown-in and batt insulation slow conduction but do not stop air, so piling more on top of an unsealed ceiling has limited effect. The other possibilities are that your real losses were never in the attic (ducts, crawl space, or the heating system), or that the winter was colder and the savings are there but hidden. Compare usage per heating degree day year over year before you conclude the work failed.
How do I know if my heat pump is running on backup heat?
Many thermostats show an indicator such as “aux heat,” “auxiliary,” or “em heat” when the resistance strips are on. If yours does not, the air at the register gets noticeably hotter and the system pulls far more power. The clearest evidence is a step change in kWh on the bill that does not match the weather. If you suspect it, call an HVAC technician, not an insulation contractor. Common causes are a failed outdoor sensor, low refrigerant charge, a defrost control problem, emergency heat left switched on, or a deep thermostat setback that triggers auxiliary heat every morning.
Should I replace my windows to lower my heating bill?
Usually not as an energy decision. Windows are a small share of your total exterior surface compared with the ceiling and the floor, and full replacement is one of the most expensive projects you can do to a house, so on pure fuel savings the payback is typically very long. Replace windows if they are rotten, will not operate, or have failed seals, or because you want them. For bill relief, sealing and insulating the attic and crawl space and getting the ducts and heating system right almost always gives you more per dollar. Weatherstripping and caulking around existing windows is cheap and does help.
My bill went up but nothing in the house changed. Is that possible?
Yes, and it happens constantly. Rates change and winters vary a lot. To rule it out, look at usage in kWh or therms rather than the dollar total, compare the same calendar month across consecutive years, and check both months against heating degree day data from the National Weather Service. If usage per heating degree day is roughly flat, your house did not get worse. Also check for a new load on the same bill: an EV, a hot tub, a failing water heater element, or a space heater running in a cold room.
Can you tell me what is wrong without coming out?
We can narrow it down over the phone and we are happy to do that for free. What we cannot do is diagnose a house we have not seen, and anyone who gives you a confident cause and a firm price over the phone is guessing. The visit is where we get into the crawl space and the attic, measure what is actually there, look at where the ducts run, and find out whether the problem is even ours. If it is not, we will tell you who to call.
What is the cheapest thing to fix first?
Almost always air sealing, because it is the smallest line item on any insulation estimate and it is what makes everything else work. After that it depends on the house. A crawl space with fallen batts and open vents is usually next in a Seattle home, then the attic, then ducts. The expensive envelope work should come after the free diagnosis, not before it. And if the heating system is the problem, fix that first, because no amount of insulation compensates for equipment making heat the expensive way.