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Review, approve, and chase subcontractor change orders with forms, DeepSeek, Gmail, and Google Sheets

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Created by: Khaisa Studio || khaisastudio
Khaisa Studio

Last update

Last update 2 days ago

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Change orders that start before anyone signs are how budgets drift. This workflow puts subcontractor change orders on a hosted form, has an AI agent read the scope against your contract rules, routes the decision by fixed money and time thresholds, and lets the PM or owner approve with one click. It also catches resubmissions and chases decisions that slip past their due date.

Last updated: November 2026.

Quick Overview

A subcontractor submits project, contract reference, trade, amount, schedule impact, scope and email on an n8n Form. Bad requests are logged with the reasons and the submitter is told what is missing. Valid requests are checked against the Change Orders register so the same change is not reviewed twice. A DeepSeek reviewer returns a risk level, scope read, cost signal and open questions, and fixed thresholds decide the path: small and short changes go to the project manager, everything else needs owner sign off plus a Google Calendar review slot. Approval emails carry signed approve and reject links. A webhook records the decision in Google Sheets and emails the subcontractor, a weekday lane chases overdue decisions, and a Monday digest lists what is still waiting.

How it works

  1. The form collects the change order, and a Code node normalizes it, builds a CO reference and checks for missing project, subcontractor, trade, scope, email, amount or schedule days.
  2. Rejected requests are appended to Rejected Submissions and the submitter gets an email listing the problems.
  3. Valid requests read the register. A match on subcontractor, project and amount from the last 14 days that is not rejected triggers a duplicate email and stops there.
  4. The AI agent returns risk, scope clarity, cost signal, questions, summary and a PM note, and a Code node parses it with safe defaults.
  5. Decide Approval Route sends changes up to USD 2,500 and 2 days to the PM, and everything else to owner approval with a 5 day decision window.
  6. The change order is logged as pending_review, the PM is emailed, and the subcontractor gets a receipt telling them not to start yet.
  7. Owner approval items get a calendar slot and an owner email. Approve and reject links are added to whichever email holds the decision.
  8. Clicking a link calls the decision webhook. Apply Decision Rules checks the shared key, the decision value, that the item is still pending and that a PM cannot decide an owner item.
  9. Allowed decisions update status, decided_by and decided_at, email the subcontractor and show a confirmation page. Refused ones show the reason.
  10. Weekdays at 08:00, pending items past their decision date get one reminder, and Mondays at 07:00 the aging digest lists items older than the aging window.

Setup

  1. Connect Gmail, Google Sheets and Google Calendar, and add an OpenAI-compatible credential pointed at DeepSeek on Risk Model.
  2. Create Change Orders and Rejected Submissions tabs, and add decided_by, decided_at, reminder_sent and reminder_at columns to Change Orders.
  3. Set the PM, owner and site emails in Normalize Change Order, Find Overdue Decisions and Set Aging Window.
  4. Activate the workflow, then set DECISION_URL to the production URL of the decision webhook and choose a long DECISION_KEY in both code nodes.
  5. Submit a test change order under USD 2,500 and click the approve link to see the full loop.

Quick Answers

Can a project manager approve a large change order?
No. Items routed to owner approval refuse decisions made with a PM link.

What stops someone from guessing a decision link?
Each link carries a shared key that Apply Decision Rules checks before anything is written.

Does the AI approve anything?
No. It only prepares a risk read. Money and schedule thresholds pick the route, and a person clicks the decision.

What if nobody decides in time?
The PM or owner gets one overdue reminder, and the item keeps showing in the Monday aging digest until it is decided.

Additional info

Built with n8n. Need an assessment on your business? Feel free to reach out at https://khmuhtadin.com/consultation/