Sammamish home prices by decade built tell a story most buyers do not expect: a house built in the 1980s sold for a higher median price per square foot over the past year than a house built in the 2000s or 2010s. The newer home still costs more in total, because it is usually much larger. We pulled every qualifying house sale in Sammamish from King County Assessor records for the 12 months from September 2025 through August 2026, 508 sales in all, and grouped them by the year each home was built.

Here is what the numbers show, what they do not show, and how buyers and sellers can use them.

How We Built the Sammamish Home Prices by Decade Built Numbers

Every figure here comes from the King County Assessor's public data downloads, so anyone can reproduce them. We matched three files: recorded sales, residential building records and parcel records, and kept only parcels the Assessor lists in the City of Sammamish.

• Houses only. Single-family homes and townhomes on their own parcels, one house per parcel. Condominiums are tracked in a separate Assessor file and are not included.
• Market sales only. Warranty and statutory warranty deeds with no sale reason and no Assessor warning flag. That removes quit claim deeds, estate transfers, related-party sales and other transfers that do not reflect an open-market price.
• Decade built is the Assessor's year of original construction. A 1987 house with a new kitchen and roof is still a 1980s house in this data.
• Price per square foot is sale price divided by the Assessor's total finished living area, which includes a finished basement.
• Timing. Deeds take a few weeks to record, so a handful of late-August sales may not appear yet.

These are medians, the middle sale in each group, so a single lakefront estate or a small fixer does not pull a group far in either direction. Removing the 14 lakefront sales changed no group's median price per square foot by more than a few dollars.

Sammamish Home Prices by Decade Built: Total Price Rises With Size

Read top to bottom, the median sale price climbs with each decade, from $1.34 million for homes built before 1980 to $2.05 million for homes built in the 2010s. It is tempting to read that as "newer is worth more." The size column tells a different story.

The median home built in the 1980s has about 2,260 square feet of finished space. The median 2010s home has about 3,540, more than half again as much. Homes built in 2020 or later are larger still, at about 4,090. Most of the price gap between decades is a size gap. Builders on the Plateau put up steadily larger houses as the city filled in, and buyers today are paying for that space.

What this means: comparing a 1985 house and a 2005 house on list price alone compares two different products. Price per square foot, while imperfect, lines them up more fairly.

Price Per Square Foot by Decade Built in Sammamish

On a per-square-foot basis, the ranking changes. The 1980s group led every group built before 2020, at a median of $626 per square foot, followed by the 1990s at $617 and pre-1980 homes at $598. Homes from the 2000s ($572) and 2010s ($582) came in lowest.

Our read of why, and it is an interpretation rather than something the data proves:

1. Smaller homes carry a higher price per square foot. Why it matters: a lot, a kitchen and a garage cost roughly the same whether the house is 2,200 or 3,500 square feet, so each foot of a smaller house carries more of that fixed value.
2. Many older homes sit on larger or more established lots. Why it matters: land value is part of every sale price, and a mature lot in a settled neighborhood is part of what buyers pay for in a 1980s house.
3. Many older homes have been updated. Why it matters: the Assessor rarely records remodels in these files, so a 1988 house with a 2019 kitchen still counts as 1980s. Updated older homes likely lift that group's numbers.

The 2020s group stands apart at $658 per square foot, but with only 22 sales, a few large new builds can move that figure noticeably. We would not draw a conclusion from it beyond "new construction sold at a premium."

How Many Sammamish Homes Were Built in Each Decade

Sales volume by decade tracks the housing stock. Using the same Assessor records, Sammamish has about 19,200 houses on their own parcels. Of those, about 5,550 were built in the 1980s and about 4,840 in the 1990s, together 54 percent of the city's houses. Another 2,600 predate 1980, about 3,360 were built in the 2000s, about 2,340 in the 2010s, and about 500 since 2020.

That is why the 1980s and 1990s groups have the largest samples here, 140 and 145 sales, and why their medians are the most dependable. If you are shopping in Sammamish, the odds are good that the house you tour is 30 to 45 years old. Our guide to buying a 1980s or 1990s home in Sammamish covers the plumbing, siding, systems and permit history worth checking in a house from that era.

How This Year Compares to the Year Before

We ran the same filters for the prior 12 months, September 2024 through August 2025 (566 sales). The median price per square foot was lower this year in every decade group, and the overall median price per square foot fell from $643 to $606. The overall median sale price moved from $1,727,500 to $1,650,000.

That lines up with the King County Assessor's own 2026 valuation, which put average total values on the north and south Sammamish Plateau about 4.4 to 4.5 percent lower than the prior year. If your new assessment looks out of step with sales like yours, our guide on how to appeal your Sammamish property assessment walks through the process. For the wider picture, see our Sammamish housing market report for 2026 and our short answer to how much homes in Sammamish cost in 2026.

What Sammamish Home Prices by Decade Built Mean for Buyers

• Compare on size, not just price. A 1990s house and a 2010s house at the same list price are often very different amounts of house. Look at price per square foot alongside total price.
• Budget for age, not against it. An older home's lower total price often comes with maintenance and updating ahead. Know the age of the roof, systems and siding before you compare.
• New construction is its own market. With few new homes selling each year, builder pricing and incentives matter more than decade medians. Our Sammamish new construction builder guide covers where those homes are.

What Sammamish Home Prices by Decade Built Mean for Sellers

• Your decade is a starting point, not a price. These medians span the whole city. Your neighborhood, lot, condition and updates will place your home above or below the median for its decade.
• Updates show up in the comparison. Because the Assessor rarely records remodels, buyers and appraisers judge them in person. Our guide to remodel ROI in Sammamish covers which projects tend to return value.
• Some older homes sell for the lot. On larger parcels, buyers sometimes weigh a rebuild. Our guide to teardowns and custom rebuilds in Sammamish explains how that math works.

Frequently Asked Questions About Sammamish Home Prices by Decade Built