The honest answer is that it depends on what is wrong with your house right now, and nobody can tell you a number without seeing it. What we can do is give you the framework the number comes from, so you can work out your own before anyone quotes you.
You have probably already read that spray foam cuts energy costs by 30 to 50 percent. Figures in the 20 to 50 percent range get quoted all over this industry, and some contractors will even “guarantee” a minimum 20 percent. Those are marketing numbers. They come from the best possible starting point: a house that was leaking badly, with almost no insulation, in a climate that punishes it. If that is your house, a big number is plausible. If your house is already reasonably tight, it is not, and no amount of foam will make it so.
Our position on this, plainly
We will not promise you a savings percentage. We would rather set an expectation you can hold us to than sell you a number we cannot back up. What we will do is look at your actual house, tell you what is costing you money, and tell you honestly when something cheaper than spray foam would fix most of it.
Why a percentage is the wrong thing to ask for
A percentage is a comparison between two things: what your house does now, and what it will do after. The “after” is fairly predictable, because a properly installed, correctly specified assembly performs in a known way. The “before” is where all the variation lives, and the before is different in every house on your street.
So when a contractor promises you 25 percent without crawling under your floor, they are not telling you about your house. They are telling you about an average of other people’s houses, most of which are not in Washington. Ask them how they arrived at it. A good answer involves your fuel, your square footage, your existing insulation, and where your air is leaking. A bad answer is a shrug and a brochure.
The four things that actually decide your number
1. The gap between where your house is now and where it ends up
This is the big one. A 1948 Seattle bungalow with an uninsulated, unsealed attic, open balloon-framed wall cavities and a vented crawl space with batts hanging down has enormous room to improve. A 1998 Kent build with decent attic insulation and a sealed envelope has very little, and the work will pay back slowly if at all. Same product, completely different result, because the starting line is in a different place.
| Where your house starts | How much room there is | What usually matters most |
|---|---|---|
| Uninsulated, unsealed attic; drafty; cold floors | A lot | Air sealing plus attic work, in that order |
| Old batts, settled or wet, rodent damaged | Meaningful | Removal first, then the right replacement |
| Vented crawl space, batts falling out, cold floor | Meaningful, and comfort improves fast | Rim joists and crawl space walls |
| Decent insulation, few obvious leaks | Little | Probably ducts or equipment, not insulation |
2. What you heat with, and what you pay per unit
Two houses can lose exactly the same amount of heat and get completely different bills. Electric resistance heat (baseboards, wall heaters, an old furnace with strip heat) turns every unit of energy into one unit of heat, and you pay Seattle City Light rates for all of it. A gas furnace on the Eastside on a PSE rate behaves differently again, and a heat pump different still, because a heat pump moves several units of heat for every unit of electricity it draws.
That matters for payback in a direct way. If you are on electric resistance heat, reducing heat loss removes the most expensive kind of energy from your bill, so the dollars move fastest. If you have an efficient heat pump, the same reduction in heat loss removes fewer dollars, because those dollars were cheaper to begin with. Neither is a reason to do or not do the work. It is a reason to run the math with your own rate rather than someone else’s.
3. Our climate does not reward the same things a cold climate does
Seattle is climate zone 4C, marine. That means a long, damp, mild heating season rather than a short brutal one. We do not get the sustained deep cold that makes raw R-value the dominant factor in Minnesota. What we do get is months of cool damp air, wind-driven rain, and a heating season that never quite ends.
In that pattern, air sealing and moisture control very often deliver more felt benefit per dollar than adding inches of insulation. Stopping cold damp air from moving through the envelope does more for a Seattle house than pushing an attic from R-38 to R-60. That is a big part of why we will sometimes point a homeowner at air sealing before we talk about foam at all.
4. Comfort, which is real and never shows up on the bill
Some of the return on this work is not financial, and pretending otherwise does nobody any good. The bonus room over the garage finally holds its temperature. The floor over the crawl space stops being cold in February. The draft along the baseboard in the back bedroom goes away. The house stops feeling clammy.
People tell us about the comfort long before they tell us about the bill. It will not appear in a payback calculation, and it is frequently the thing they say was worth the money.
How to work out your own baseline
You do not need us for this part, and you should do it before you take any bids. Your utility keeps your history and it is the most honest data you will find about your own house.
Pull 24 months of usage
Log into Seattle City Light or PSE and download the actual usage, not just the dollar amount. Two years lets you see a pattern rather than one bad month.
Separate heating from everything else
Take your lowest summer month as your baseline load (fridge, lights, hot water). Everything above that line in winter is roughly your heating. That is the part this work can touch.
Convert to dollars at your rate
Multiply your winter heating usage by what you actually pay per kilowatt hour or per therm. Now you know the size of the prize. It is often smaller than people expect, and sometimes much larger.
Decide what a reasonable payback looks like to you
Against that annual heating cost, weigh a real quote. If the number only works over 30 years, we will tell you so rather than talk you into it.
The trap in before-and-after comparisons
Do not compare last January to this January and call the difference your savings. A mild winter and a cold winter can differ by a large margin all on their own, and Puget Sound winters swing. If you want a fair read, compare usage against heating degree days for each period, or give it two full seasons. Plenty of people have credited insulation for a warm winter, and plenty have blamed it for a cold one.
When insulation is not the thing that will cut your bill
This is the part most contractors leave out, so we will say it clearly. Three situations come up regularly where spray foam is not the right first dollar.
- Air sealing alone captures most of the benefit. In some houses, sealing the top plates, the chimney chase, the can lights and the rim joist for a fraction of a foam job gets you most of the comfort and most of the savings. When that is true, we will tell you, and we will quote you that instead.
- Leaky ducts are dumping your heat outside the house. Ducts running through a vented crawl space or an unconditioned attic can lose a serious share of what your furnace produces before it ever reaches a register. No amount of foam in the walls fixes a duct system that is delivering heat to the dirt.
- The equipment is oversized, failing, or badly matched. An oversized furnace short cycling all winter, or a heat pump locked into its backup strip heat because something is wrong with it, will dominate your bill. That is an HVAC problem and it needs an HVAC answer first.
If we come out and find one of these, you will hear it from us. It costs us the sale sometimes. We would rather lose a job than take money for work that will not solve the problem you called about. If high bills are the reason you are reading this, start with why your heating bills are so high.
Tax credits and rebates
Federal energy-efficiency tax credits for insulation and air sealing exist, and Washington utilities have run rebate and incentive programs for this kind of work. Either can change the economics of a project, sometimes substantially, so they are worth checking before you decide.
We are not going to quote you amounts, percentages, caps, or eligibility rules on this page. Those change, and getting them wrong would cost you real money. Verify the current federal credit directly with the IRS, and check current rebates with your own utility (Seattle City Light or PSE) for your address and your specific measure. We are insulation contractors, not tax advisors, and you should treat anyone in this trade who talks confidently about your tax situation with some caution.
So what do we tell people?
That the size of the win is the size of the problem. That if your attic is bare and your crawl space is open to the weather, the change will be obvious in both the bill and the house. That if your house is already in decent shape, the honest expectation is modest, and you should know that before you spend. And that whichever of those is true for you, we will say it out loud before you sign anything.
If you want the broader version of this question, including where the money goes and whether the work makes sense at all here, read is spray foam insulation worth it in Seattle, and see real ranges on what spray foam costs in the Seattle area.
Common questions about energy savings
Can you guarantee I will save 20 percent on my energy bill?
No, and we would not trust a contractor who does. Your savings depend on how much heat your house is losing today, what you heat with, what you pay per unit, and how you use the house. None of that is knowable from a phone call, and a lot of it is outside our control. Figures in the 20 to 50 percent range circulate widely in this industry, but they describe worst-case starting conditions, not a promise about a specific home. What we will give you is an honest read on your house and a straight price.
How long does spray foam take to pay for itself?
It depends entirely on your annual heating cost and the size of the job. The way to work it out is to pull your utility usage, subtract your summer baseline to isolate heating, price that at your actual rate, and compare it to a real quote. A house with an uninsulated attic and electric resistance heat can see a fast return. A house already in reasonable shape may take a long time, and if we think that is your situation we will say so before you spend.
Is air sealing enough on its own?
Sometimes, yes. In a mild damp marine climate, uncontrolled air movement is often a bigger driver of heat loss and discomfort than insufficient R-value. Sealing the top plates, chimney chase, plumbing penetrations, recessed lights and rim joist can capture a large share of the available benefit for a fraction of the cost of a full foam job. When that is the better buy for your house, that is what we will quote.
Why did my bill not drop after I added insulation?
Three common reasons. First, weather: a colder winter can wipe out a real improvement in a naive year-over-year comparison, so compare against heating degree days or wait two full seasons. Second, something else dominates, usually leaky ducts in an unconditioned space or heating equipment that is oversized or failing. Third, the house was already decent and the remaining room to improve was small. Behaviour matters too, since people often raise the thermostat once the house is finally comfortable, which spends the savings on comfort.
Does a heat pump change whether insulation is worth it?
It changes the math, not the logic. A heat pump delivers several units of heat per unit of electricity, so each unit of heat loss you eliminate removes fewer dollars than it would in an electric resistance home. The flip side is that a tighter, better insulated house lets a heat pump hold temperature without falling back on its resistance backup heat, which is the expensive mode. Reducing the load is generally good for a heat pump. Just run the numbers with your own rate.
Do federal tax credits or utility rebates cover this?
Federal energy-efficiency tax credits for insulation and air sealing exist, and Washington utilities have offered rebates for this type of work. Amounts, caps and eligibility rules change, so we do not publish specifics. Confirm the current federal credit with the IRS and check current programs directly with Seattle City Light or PSE for your address. We are insulation contractors, not tax advisors.