# We Rebuilt a Contractor's Excel Logic as an App > A steel contractor ran estimating in one Excel workbook. We rebuilt its logic as a custom app in 6 weeks. Read how, then upload your estimating sheet for a free quote. Source: https://llamapress.ai/we-rebuilt-a-contractors-excel-logic-as-an-app | Updated: 2026-08-15 --- A real build, start to finish One steel contractor. One estimating workbook. Six weeks later, the same pricing logic ran as software their whole team uses. Here is how it happened, and how to get a free quote for yours. Before: Excel Spreadsheet ![Before: RSB Contracts' steel estimating spreadsheet](https://llamapress-ai-image-uploads.s3.us-west-2.amazonaws.com/esdmd9wkjkulczhgy9e7l77xemek) One file, one person at a time 6 Weeks After: Custom Estimating Software ![After: the same estimate in RSB Contracts' custom estimating app](https://llamapress-ai-image-uploads.s3.us-west-2.amazonaws.com/uxsgsdkjxlsss7e7cymnh93tn03x) Same logic, whole team, every estimate saved 62% Faster The story ## The spreadsheet was the business RSB Contracts fabricates and erects structural steel. Like most contractors, they priced work in Excel. The workbook held everything: member weights, supply and fab rates, waste factors, markup rules, and years of pricing judgment baked into the formulas. That workbook worked. That was the problem. It worked so well that the whole company depended on one file. One person could price at a time. Revisions meant new copies. Old bids lived in folders nobody searched. The managing director spent over 100 hours trying to improve it with ChatGPT before he found us. ### What we actually did We did not hand them generic estimating software and ask them to adapt. We took the logic that already lived in their workbook and rebuilt it as a custom web application. Their rate tables. Their buildup rules. Their markup ladder. The app prices the way the spreadsheet priced, because it was built from the spreadsheet. Our AI coding agent, Leonardo, does the heavy lifting. It reads the workbook, and we shape the result with the contractor on short calls until the numbers match. That is why a build like this now takes weeks instead of a six-figure software project. ### What changed for the team The estimating sheet became a system that runs tendering, revisions, production tracking and purchase orders. Commercial, production and finance now share one view of every job. Estimates go out 62% faster, and each estimate costs about 40% less to produce. Every bid is saved in a database the team can search, instead of in old file copies. > "I spent 100+ hours trying to improve our estimating spreadsheet with ChatGPT before I found LlamaPress. This new software reflects the way we actually think and has made everything so much more streamlined and practical." You can read the full build at [llamapress.ai/portfolio/rsb](https://llamapress.ai/portfolio/rsb). ### Why this matters for your sheet Your estimating spreadsheet is not a mess to be replaced. It is a specification. It already describes exactly how your business prices work, down to the last markup rule. Most contractors assume turning it into real software costs $100K and takes six months. It used to. AI changed the economics, and that is the whole reason this page exists. Send us the sheet you price with today. We will look at what is in it and reply with a free quote for building it as your own app. Free quote. No card. No commitment. ## Upload your estimating sheet for a free quote Attach the workbook you price with today. Excel, macros and all. A messy sheet is fine. We review how it works and reply within one business day with a free quote for rebuilding it as your own app. Your rates stay private. We use your file only to prepare your quote. We do not share it, sell it, or train public models on it. ## Fair questions before you hand anyone your spreadsheet ### What does the free quote include? We review your spreadsheet and reply with what we would build from it, how long the build takes, and what it costs. You decide from there. No obligation. ### What happens to my spreadsheet and my rates? We use your file to prepare your quote and for nothing else. We do not share it or sell it. Your margins and rate logic stay yours, and inside the app you control who can see them. ### My sheet is a mess. Does that matter? No. A messy sheet with real logic in it is the best starting point we can get. Broken macros included. RSB's workbook was years of accumulated formulas, and that build is the one on this page. ### Do I have to stop using Excel? No. Keep Excel where Excel works. The app imports and exports spreadsheets whenever a client or a general contractor asks for one. ### Who owns the app? You do. It runs on your own instance, and paid plans can include access to the source code. ## Your spreadsheet already knows how you price. Find out what it takes to make it software. Upload the sheet, and within one business day you have a free quote for your version of the app on this page. ### Get your free quote Attach your sheet. We reply within one business day.