The Machine Readable House

It’s early morning sometime in 2030 and you are finally on the property ladder. Your 1960s bungalow is small, but exactly what you needed at the price you needed it, and somehow you managed to find one that gave the slip to the grey flippers of the mid-aughts. Bravo. You are blessed. And yet, you find yourself dreaming out the window over the kitchen sink, frugal home-brewed coffee in hand, about adding a gas-powered grill and built-in outdoor kitchen to your perfect slate patio. “Siri, show me the gas lines.” The house peels away like the schematics in Silo: floorplans, electrical… “ah there it is,” the gas lines. You can see that the main actually reaches the house’s side near the back fence gate. “Shouldn’t be too much to add a line you think.” Maybe while you’re swiping through these files you pass copies of permits pulled, a foundation repair, 1997 a window replaced…

“Wait a minute,” you think. “Isn’t this an informative real estate Substack? Not to yuck on your pet screenplay, but isn’t there a 10% chance we are all dead by 2030 according to that one guy? What are you on about?”

You’re right. Let me set aside my childish things and get to the point. I’m talking about the UAD 3.6: the new appraisal standards rolling in from Fannie Mae and Freddie Mac. Are your eyes glossing over? Wanna go back to my screenplay? While the new appraisal form won’t map the gas lines in your house, it will start collecting considerably more structured information about your house than the appraisal reports we are used to. As of now it won't create a magical high-tech housing archive and even if it did do you think our corporate overlords would just hand that over to you with the house keys? Not without a subscription, I think not.

"So what does this form do and why do I care?" I’ll get to why you should care or at least get curious later, but first, the easiest way to think about it is this. The UAD 3.6 changes a residential appraisal from a standardized form that humans fill out into a much more structured dataset that can also be rendered as a report humans read.
The old UAD dates back to the 2010–2011 era. It standardized certain appraisal fields, but appraisers still relied heavily on fixed forms and free-form narrative commentary. When something didn't fit neatly into the form, important information could wind up buried in an addendum as prose. FHFA's original stated objective for standardized appraisal data was to improve the consistency and quality of the information Fannie Mae and Freddie Mac receive and give them deeper collateral information for mortgage and risk-management decisions.
UAD 3.6 is a major expansion and modernization of that system. Fannie and Freddie describe the new structure as “data-driven, dynamic” and explicitly identify the reliance on free-form commentary under the old forms as a limitation. Instead of a bunch of different appraisal forms for different situations and property types, UAD 3.6 introduces a single flexible Uniform Residential Appraisal Report structure that changes depending upon the property and assignment.

And the 3.6 isn't some Fannie Mae version number pulled out of thin air. The data structure is aligned with MISMO (The Mortgage Industry Standards Maintenance Organization) Reference Model 3.6, an industry standard designed so mortgage systems can exchange information in standardized, machine-readable ways. In layman’s terms: a standardized computer-readable mortgage-data file.

The PDF appraisal that a buyer, lender, agent, etc. sees is essentially the human-readable representation. Underneath it is structured data.

Imagine taking more and more of the information that might describe our little bungalow and breaking it out of human-made sentences and into discrete data points. Instead of, “The subject is a 1964 brick bungalow with an attached two-car garage and rooftop solar panels…” you get something more like: “YearBuilt = 1964. Exterior Material = Brick. Garage Type = Attached. GarageSpaces = 2. Solar = Yes.”

Yes, appraisals already had a lot of structured fields, but UAD 3.6 expands how and what information can be captured as discrete, standardized data. Are your eyebrows perching up a bit now?

Sidebar if I catch a stray appraiser: look, I don’t know what your forms look like on your side, just the work product you send the buyers. So if you already have a little box for garage type? Great. I’m just painting a picture here, nerd.

“Girl, I just want info on how to buy a house.” I know! But you should care about this stuff too. This is the machinery behind your house hunt and some of these gears may be what snags you up: not your avocado toast. So roll with me here.

The appraiser is just one hand in your home-purchase journey and the UAD 3.6 change doesn’t just touch their workflow. Some of that increasingly detailed property data has to come from other sources too because appraisers don’t just spawn at every sale making note of the comparable on their clipboard for credits in a bonus mission. One of those sources is the MLS. That means that half-assed agent Becky, who helped you get that crappy duplex rental with the crazy owner next door? Yeah, Becky’s half-assed listing data from her one sale in 2020 became a part of somebody’s research too. While it has always been best practice to give the MLS the most accurate information possible agents may expect to have more conversations with appraisers to account for data fields not yet available in their MLS input. In fact agents might expect their MLS associations to start expanding available data fields. We don’t know yet. Yay more work for me.

***buyer sidebar. The MLS is this big chunky database of houses realtors use to aid your home search. It’s the thing that Zillow pulls the pretty pictures from.***

But more work on the front end could mean less on the back end. Maybe yay for you Future Homeowner ™. When you apply for a mortgage, the lender isn’t just asking “can Bettie Buyer afford the house?” They are also assessing “What happens if Bettie Buyer stops paying us?” (Or whatever mortgage-backed security tranche this loan is packaged into. Dammit that’s an 08 sidebar for later)
“Is this home in particular really worth enough to give Bettie a big pile of money for?” That’s what the appraisal does for your lender. Appraiser goes, “yo those bricks are worth X based on all this data.” Lender goes “cool, I’m forwarding this to Freddie.” Freddie’s Computer go “Yoink brrrr”.

*** that’s the sound it literally makes while it analyzes the report for risk. On God.***

But sometimes Freddie’s computer says, “No thanks. I have data at home.” Freddie’s Automated Collateral Evaluation, sometimes called ACE, uses proprietary models, historical data and public records to determine whether a loan needs an appraisal at all. And they share their numbers on the time savings. As of Q2 2025, Freddie says purchase loans using ACE closed an average of 14 days faster than loans using traditional appraisal reports and refinances using ACE averaged a 12-day timeline boost. That makes sense when there’s no appraiser respawn timer, no appointment to walk the subject property, no report to generate and review… That is potentially two weeks shaved off the time you have to wait to get keys and go finance furniture from Quince. Fannie has its own version called Value Acceptance. That’s when a Desktop Underwriter (computer) goes, “dot dot dot thinking dot dot dot checks armory cache of millions of appraisals and property analytics dot dot dot thinking dot dot dot. Value accepted.”

Historical appraisal data is already being used to decide whether appraisals are necessary at all. The ouroboros of lending.

So what happens if the snake grows? Like, gets better food? WHAT DOES IT MEAN DAMMIT!

We don’t really know from here. Potentially the computer becomes more informed and more confident on properties. Potentially more properties move through appraisal alternatives. Potentially lenders get faster decisions. Potentially the line between “We need a human’s input on this house” and “We know enough about this house” gets nerfed.

Then what happens to all the snake’s food? Who gets to see it? Just the wizards over at Fannie and Freddie? Will AMCs (Appraisal Management Companies) stockpile their own hoard to sell? Do they already?

***shit I should look that up but I have an appointment to make***

How much will the systems surrounding a real estate transaction eventually know about an individual house?

Today it’s pretty boring and straightforward “YearBuilt. Condition. Quality.” Tomorrow, sky’s the limit. “Wiring type. Solar Battery Brand. Window Ratings.” Once it’s machine-readable data it isn’t just about how much faster your turnaround from offer to keys folds in. It’s about acceleration and interoperability. The UAD 3.6 doesn’t cross-play to Zillow right now. But what if? What if your roofer, your plumber, your lender, your appraisal district all increasingly building out their own datasets start to inform one another?

Maybe Siri won’t be able to pull up your gas line schematic on a projection over your kitchen sink in 2030. But somewhere across various servers there’s a lot of info about your 1960s bungalow. So for now, faster cheaper closings? Fuck yeah. Better valuation consistency? Useful. The rest is unwritten.