How I Built a Construction Cost Estimator with AI — And What I Learned Along the Way
I'm going to be straight with you. On January 24th, 2026 I made a decision that scared me a little. I was going to build a professional construction cost estimator — from scratch — using AI. I had thirty years of residential design and estimating experience, a head full of construction knowledge, and a basic understanding of Excel that amounted to =sum(a+b). That was my starting point.
The goal was straightforward enough. I've been collecting preliminary sketches for 25 years. I wanted to turn them into stock plans for sale — a portfolio, a passive income stream, a way to position myself with builders and homebuyers. But I didn't want to sell just a floor plan. I wanted to give buyers something the other plan services don't: a Specification Outline that tells your contractor exactly what to build, and a cost estimate that gives you the confidence to sit across the table from a builder and ask the right questions.
To do that, I needed the estimator first.
Hiring an AI I'd Never Met
Three days before I committed to the project, I read an article about Claude Code. I decided to hire it. That's genuinely how I thought about it — hiring a collaborator with skills I didn't have. I'd been using AI in Notion for construction project notes, so I wasn't starting from zero. But working in a terminal with Python scripts and bash commands? That was new territory.
What I found is that the learning curve isn't really about the technology. It's about communication. The clearer you can describe what you want — and what you don't want — the better the output. That's no different from giving a set of redlines to a draftsman. The tool changes. The discipline doesn't.
The Two-Week Mind Dump
Here's where I'll save you some time if you're considering something similar: I spent two weeks doing a complete mind dump of everything the estimator needed to be. Every question I could think of. Every data source. Every trade, every material, every labor rate.
It was too much. I got distracted by details that didn't need to be solved on day one — lumber index extraction, assembly pricing, door and window schedules, plumbing fixture databases. I approached it the same way I approach a floor plan: the whole vision in my head at once, trying to make sure it was practical and buildable before committing.
That instinct isn't wrong. But for building software, it muddied the water. The better approach, which I figured out around week three, is to break it into smaller parts and solve one problem at a time. Obvious advice. Hard to follow when you can see the whole thing clearly in your head.
What It Looks Like Now
Four weeks in, the estimator is something I'm genuinely proud of. It covers every CSI MasterFormat division relevant to residential construction — concrete, framing, exterior, doors and windows, finishes, appliances, plumbing, HVAC, electrical. It pulls from the 2026 National Construction Estimator with Omaha-area labor adjustments. It has cascading dropdown schedules for doors, windows, plumbing fixtures, and electrical. It locks in lumber commodity pricing at the time of creation so an estimate built in March doesn't recalculate when lumber spikes in September.
That last detail matters more than it sounds. A bid is a snapshot. The tool treats it like one.
One Thing Nobody Tells You About Working With AI
I noticed something around the second week that genuinely made me laugh. I've spent thirty years in construction and design, and I've always had to be conscious of how I deliver criticism. I'm direct. I don't keep it fluffy. But I caught myself softening my feedback to the AI — trying not to insult it.
That passed quickly. The right move is to be direct, specific, and honest about what's not working. When I did that, the responses got better. It pushed back with clarifying questions, which led to better solutions than I'd originally asked for. That dynamic — direct feedback leading to better outcomes — is exactly how good design collaboration works. Turns out it applies here too.
What's Next
The estimator gets tested with area builders before it goes anywhere near a customer. That's non-negotiable. Pricing needs to hold up against real bids from people who build in this market every day. Once it does, it becomes the add-on that turns a stock plan purchase into something a homebuyer can actually use.
The first plan is in development. More on that soon.
*The estimator is the foundation. The plans are what it's built to support. If you want to know what a home will actually cost before you commit — that's exactly what RED is building toward. Specification Outline included with every plan. Construction Cost Estimate available at checkout.*