Plat map sampleA plat map comes with your preliminary title report (provided by your title company when you purchase or sell a home in California), tucked away at the back and somewhat mysterious with lots of numbers in small print. It holds quite a bit of helpful information if you know what it is you’re seeing. Today we’ll view a sample of one of these – breaking down the plat map shown as a small thumbnail image on the right to more readable parts so that you can learn how to “read” or understand a plat map. By the way, this example we’re using is for a lovely San Jose neighborhood in the Cambrian Park district which borders Los Gatos and is near Carlton Avenue, Los Gatos-Almaden Road and Union Avenue.

First have a quick look at the thumbnail image on the right.  You can tell it’s some sort of map with official looking writing in the lower corners.  Perhaps most salient even in the smallest image, one important feature of the plat map is that it provides the orientation of the properties (north/south/east/west).  That info is now readily findable online, but this used to be the easiest way (and most accurate) to answer the question “which way does the home face?” Look at the map, find the parcel and you’ll know its orientation.

Plat Map with part of Esther Drive in San Jose

The plat map also provides the Tract Number (and often the name given by the builder for the subdivision – in this case, Carlton Terrace). Along the right side, you can see the source of this information: the office of the county assessor for Santa Clara County.

Let’s look a little closer still.

Plat Map closeup showing parcels

Looking at an individual address or lot, you’ll note that there’s more information.  The house number for each parcel is listed, the shape of each property given (parcel boundary) and the approximate lot dimensions are provided too.  When a dimension is the same on both sides or as with the adjoining property, it’s not listed.  In the case of these homes, most of them have 60′ to 61′ wide lots and approximately 110′  to 113′ deep lots –  very typical lot size for a Cambrian Park home.

What about the large numbers in the middle of each property?  One of them is the builder’s lot number and the other is the parcel number assigned by the to the property by the county assessor’s office. The parcel number should be underlined and more prominent (bolded, italicized etc.).

The assessor’s parcel number, or APN, for each property is created by referring to the Asessor’s Book Number, the Assessor’s Book Page Number plus the individual parcel number, with each of these sets separated by hyphens.  To find the book and page number, look in the corners of the page with the plat map – they will be listed clearly.  In our sample, note the lower right hand corner.

Plat map with book and page number displayed

So for the homes on this plat map, the APN will be 421-18- whatever the parcel number is for that particular home (the bolded, underlined, italicized number).

Can this information be really useful to you? You bet it can.  Sometimes we see homes for sale in which the lot size is said to be a certain amount, say 6000 SF, but having seen the yard, it appears much, much larger (or smaller). By studying this page, you can check the dimensions and see if the number quoted as the lot size is correct or not.

Several times in my career I have found a lot size to be under-estimated or under-reported in the county records.  This is especially true with irregularly shaped lots (such as pie-shaped lots or lots with many sides to them – more than four).  If a builder primarily subdivided with 6000 SF lots, that number may be inputted to the county records for every parcel, even if the one you’re looking at buying or currently own is much, much more.

I won’t say it’s a fun geometry project, but learning that a home is sitting on a 9000 or 10,000 SF lot rather than 6000 is money in the bank if you’re buying or selling such a home.  Many Realtors will not get the lot measured in person or referencing the plat map, but this extra step is extraordinarily helpful in understanding a home’s true value.   So first we must understand how to read a plat map, then know and act on what we see if there’s anything that does not look correct.

Plat maps are so important that if there’s a small typo in them, the lender for a buyer will not fund the loan until it’s corrected. (I know, it happened to me about 10 years ago on a Willow Glen home I listed and sold on Arata Court.)  When you get the preliminary title report, whether you’re buying or selling, don’t ignore it!  The rest of the contents of the prelim are also important, but for today I want to encourage agents and consumers to take the time to look also at the parcel map at the end of the prelim and see if everything looks correct.  It may save you both time and money to catch any errors upfront.

Further reading:

What is a preliminary title report? Why does it matter?

Where are the easements? Request a color coded easement map from your title company!

What does “et ux” mean in the preliminary title report?

Patio Homes or Zero Lot Line Houses in Silicon Valley

  1. 3 beds, 1 bath
    Home size: 1,060 sq ft
    Lot size: 5,000 sqft
  2. 3 beds, 2 baths
    Home size: 1,965 sq ft
    Lot size: 6,451 sqft
  3. 3 beds, 3 baths
    Home size: 1,348 sq ft
    Lot size: 1,441 sqft
  4. 3 beds, 1 bath
    Home size: 1,073 sq ft
    Lot size: 8,276 sqft
  5. 3 beds, 2 baths
    Home size: 2,173 sq ft
    Lot size: 7,810 sqft
  6. 2 beds, 3 baths
    Home size: 1,359 sq ft
    Lot size: 940 sqft
  7. 3 beds, 3 baths
    Home size: 1,454 sq ft
    Lot size: 2,635 sqft
  8. 1 bed, 1 bath
    Home size: 498 sq ft
    Lot size: 535 sqft
  9. 3 beds, 3 baths
    Home size: 1,464 sq ft
    Lot size: 1,986 sqft
  10. 2 beds, 3 baths
    Home size: 1,464 sq ft
    Lot size: 1,964 sqft

See all Real estate in the Cambrian community.
(all data current as of 8/19/2018)

Listing information deemed reliable but not guaranteed. Read full disclaimer.


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Mary Pope-Handy
Sereno Group Real Estate
214 Los Gatos-Saratoga Rd
Los Gatos, CA 95030
408 204-7673
Mary (at)
License# 01153805

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