Territory Intelligence · Siding & Exterior
490,445 homes that will never buy siding.
The Cook County assessor records the exterior wall material of every residential parcel it values. Four values, no free text, and a fill rate that shames most private data you can buy. Read that one column and you learn something a siding contractor otherwise pays to learn, one postcard at a time: 44.0% of this county is solid masonry, and no creative in the world moves it.
490,445Masonry-walled homes, county-wideCounty assessor
44.0%Share of parcels with the wall field populatedCounty assessor
45.5%Masonry plus stucco: not a vinyl-siding dropCounty assessor
20.6×Township spread, highest vs lowest masonry shareDerived · assessor
01 · The field
One column, four values, 46 blanks.
The assessor's property-characteristics file carries ext_wall_material on 1,114,335 residential parcels. Exactly 46 come back empty. That leaves a populated denominator of 1,114,289, and every percentage on this page is computed against it.
Here is the distribution. Masonry: 490,445 homes, 44.0%. Frame: 343,851, or 30.9%. Frame plus masonry: 262,973, or 23.6%. Stucco: 17,020, or 1.5%. There is no other bucket, no free text, no cleanup pass required before you can trust it.
Now group it by what a vinyl or fiber-cement crew can sell into. Frame and frame-plus-masonry are the addressable market: 606,824 homes, 54.5%. Masonry and stucco are 507,465 homes, 45.5%. Stucco sits on the suppression side: different product, different crew, different sale.
The read for contractors
Nearly half of Cook County sits outside your product line before you write a headline or pick a list. That number is published, free, stable across years, and the cheapest filter you will ever apply to a list.
Exterior wall materialAssessor · n=1,114,289
02 · The waste math
What it costs to ignore one column.
Put a price on it. Assume $0.60 per piece, all in: print, list, postage, on a standard postcard at the volume a local contractor actually buys. That is an assumption, stated plainly, and the only number here that does not come out of a county file. Substitute your own rate; everything scales off it.
Drop 10,000 pieces across Cook County at the county's own wall composition and 4,554 of them land on masonry or stucco. At sixty cents that is $2,732 spent on homes that were structurally never going to answer. Extend the same logic to the whole county and mailing every non-sideable wall in Cook costs $304,479.
Here is the part that stings. Take the list most siding contractors already build, the sensible one: pre-1980 stock, owner-occupied. That is 792,241 homes, and inside it the masonry-or-stucco share is 46.7%. Higher than the unfiltered county. The age filter walked you further into the brick, and per 10,000 pieces it cost $71 more than mailing at random.
The read for contractors
Age and occupancy filters correlate with wall material, and here the correlation runs the wrong way. Adding a filter is not the same as adding precision. Wall material needs its own gate.
Waste per 10,000 piecesMasonry + stucco share · $0.60/pc assumed
| Drop | Wasted | Cost |
|---|---|---|
| Niles township | 6,504 | $3,902 |
| Pre-1980 + owner-occ. | 4,673 | $2,804 |
| County, unfiltered | 4,554 | $2,732 |
| Hanover township | 504 | $302 |
03 · The league table
Two townships, same drop, $3,600 apart.
County averages hide everything that matters here. Masonry share runs from 84.4% in North Chicago township down to 4.1% in Schaumburg, a spread of 20.6× across the same county file. Sixteen townships sit above 50% masonry and hold 560,801 homes between them. Nine sit below 25% and hold 249,606.
Work the two ends on the full suppression basis: masonry plus stucco, since neither takes vinyl. Mail 10,000 pieces into Niles township, where the two together are 65.0% of the stock, and $3,902 of your $6,000 buys nothing. Mail the same 10,000 into Hanover, at 5.0% on that combined basis, and the dead spend is $302. Same budget, same creative, same crew. Cost per reachable home goes from $1.72 in Niles to $0.63 in Hanover. The table beside this counts masonry only, so its rows read a shade lower.
One honest complication. Share and volume disagree. Lake township is 56.3% masonry, which reads as a township to avoid, yet it holds 47,092 frame homes, the largest raw frame pool in the county. High masonry share makes a blind drop expensive; it does not make a filtered drop small.
The read for contractors
Rank townships on masonry share to price your mail, then on absolute frame count to size the prize. A dense, half-brick township can still out-produce a clean suburban one if you filter. If you don't, it will eat you.
Masonry share by townshipAssessor · n=1,104,819 in-township
| Township | Homes | Masonry |
|---|---|---|
| North Chicago | 5,385 | 84.4% |
| Rogers Park | 8,041 | 76.9% |
| South Chicago | 15,795 | 75.3% |
| Cicero | 13,691 | 72.8% |
| Berwyn | 12,955 | 72.0% |
| Hyde Park | 64,063 | 69.8% |
| Niles | 32,497 | 64.7% |
| Orland | 28,255 | 18.6% |
| Bremen | 32,504 | 15.0% |
| Rich | 22,394 | 11.8% |
| Palatine | 28,174 | 11.8% |
| Hanover | 25,286 | 4.9% |
| Schaumburg | 30,628 | 4.1% |
04 · The age trap
The oldest stock is the brickiest stock.
Every exterior trade targets on build year, and for roofing that instinct is sound. For siding it backfires. Cut the county's 1,114,273 parcels with both a wall value and a build year into eras and the masonry share peaks exactly where the age filters point.
Homes built between 1940 and 1959 are 54.6% masonry, the highest share of any era, on 329,209 parcels. Pre-1940 stock runs 46.9%. Then it falls off: 34.3% for 1960 to 1979, and a low of 25.3% for 1980 to 1999. The postwar bungalow belt that looks like a perfect siding market on a map is the least sideable stock in the county.
The 2000-and-later cohort climbs back to 40.1% masonry, worth knowing before anyone assumes new construction is automatically frame. That is measured; we have not tested why it turns.
The read for contractors
If your siding list is "pre-1980, owner-occupied, 25 years since the last exterior permit," you have built a masonry list with extra steps. Run wall material first, then age. The order changes the bill.
Masonry share by build eraAssessor · n=1,114,273
05 · The partial-brick lane
What the field does not tell you.
Time for the caveat that keeps this honest. A CAMA wall field records the dominant exterior material for the structure. It does not walk the elevations. So the 262,973 homes coded frame-plus-masonry, 23.6% of the county, are not a clean yes and not a clean no. Plenty of them are brick-front with frame on the sides and rear, which is three elevations of real siding work and a smaller, easier ticket than a full wrap.
The error runs both ways. A home coded masonry may carry a frame dormer or a sided rear addition; a home coded frame may have a brick face the field never mentions. Anyone who tells you one assessor column resolves a bid is selling something.
So run three lanes. Suppress masonry and stucco hard. Mail frame hard. Hold frame-plus-masonry as its own segment with its own creative and its own close-rate assumption, because the job is partial and the pitch is different. Inside that pre-1980 owner-occupied list, the split is 240,867 frame-only homes and 181,172 in the partial lane. Dropping the partial lane as waste throws away 181,172 addresses. Folding it into core frame inflates every close-rate assumption downstream.
The read for contractors
Score the partial lane against your own sold jobs. If your close rate on frame-plus-masonry addresses is materially different from straight frame, you have just earned the right to two campaigns instead of one, priced separately.
Pre-1980, owner-occupiedAssessor · n=792,241
06 · Do this yourself
How to find the same field in your county.
This is not a Cook County trick. Most assessors that run a modern CAMA system publish a construction attribute, and most contractors never open the file. Six steps.
1. Ask for the characteristics extract, not the parcel map
The GIS parcel layer on every county open-data portal carries geometry, PIN, and usually an owner name. It almost never carries construction attributes. What you want is the residential characteristics extract behind the assessment roll. Cook publishes it. Elsewhere you may have to ask the assessor, and it is a public record when you do.
2. Find the column, then find the dictionary
Look for a header along the lines of EXT_WALL, EXTWALL, EXTERIOR_WALL, WALL_TYPE, or CNST_TYPE. Cook ships readable text. Many counties ship an integer code with the meanings in a separate data dictionary. Never guess that mapping from the code numbers. Get the dictionary, or the filter inverts and you suppress your best market.
3. Measure the fill rate before you trust it
Cook's field is populated on 1,114,289 of 1,114,335 parcels, 46 blanks in 1.11 million rows. That is exceptional. A field with heavy nulls is still worth running, but say the denominator out loud and assume the missing rows behave like the county average until you prove otherwise.
4. Read the value list for a combined category
If the value set contains something like "frame and masonry" or "brick veneer over frame," that is your review lane, and it will be large. In Cook it is 23.6% of the stock. A county offering only a binary has hidden that population inside one of the two buckets, so your suppression is either too aggressive or too loose. Find out which before you scale spend.
5. Compute the share by township or municipality first
A single county number is useless for buying mail. Cook's 44.0% average conceals a range from 4.1% to 84.4%. Group by whatever geography your county assesses on, then price each drop against its own share.
6. Join it to your own sold jobs
The public field tells you who cannot buy. Your job history tells you which of the remainder does. Join them on address and you own a targeting model no list vendor can sell you, because the inputs are your invoices and a public record.
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Method & sources
Wall-material, build-year and occupancy figures are computed from the Cook County Assessor's residential property-characteristics file as staged in the TerritoryX Cook County parcel database, covering 1,114,335 residential parcels. The wall field (ext_wall_material) is populated on 1,114,289 of them; the 46 blank rows are excluded, and every wall-material share here uses 1,114,289 as its denominator. The township league table uses the 1,104,819 parcels carrying both a wall value and a township name. The build-era table uses the 1,114,273 with both a wall value and a non-zero build year. The pre-1980 owner-occupied segment is the 792,241 parcels built before 1980 with the assessor's owner-occupancy flag set.
The $0.60 per piece mail cost is an explicit assumption, not a measured figure and not something published by any county. It stands in for an all-in print, list and postage rate at typical local-contractor volume. Every dollar figure here is that assumption multiplied by a measured parcel count, so your own rate rescales all of them proportionally. Piece counts in the waste table apply the measured masonry-plus-stucco share to a 10,000-piece drop, rounded to whole pieces; the league table is masonry only, so the two differ slightly.
Everything here is aggregate. No individual home, address, PIN or owner is identified, and nothing on this page is a claim about the condition of any specific property. Wall material is what the assessor records as the dominant exterior material for the structure, not an elevation-by-elevation survey, which is why the partial-brick section above exists.
Cook County Assessor · property characteristics
Cook County Assessor · ownership flag
TerritoryX · staged county parcel database
One column saved you $3,600 on a single drop. There are eleven more.
Wall material is the easiest filter in the county file, which is why we gave it away. The Territory X-Ray stacks it with roof age and size modeled from public LiDAR, permit suppression, storm cohort, and ownership, then ranks the neighborhoods in the towns you work. More free reads sit in the county brief.
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