Custom Software for Trade Businesses: A Case Study from the Heat Pump Industry

Two months ago, a small request came in: extend a few existing n8n automations, add one or two new ones. Not a big project, barely a line item on the calendar.

Today, more than a dozen employees at Wärme mit Konzept (WMK) use a fully custom order- and subcontractor-management tool nearly every day, built from exactly that small request. Kickoff to production go-live: under two months. That’s not an outlier, it’s a pattern we see repeatedly at TAISC when growing trade and installation businesses hit the point where spreadsheets and WhatsApp groups stop being enough. This post walks through a real project to show what that kind of digitalization actually looks like, what it costs, and when a custom solution genuinely beats off-the-shelf software.

A growing market — and a very familiar pattern

WMK plans and installs heat pump, HVAC, and solar systems, a market that gained real momentum in 2026. According to Germany’s Bundesverband Wärmepumpe (heat pump industry association), roughly 194,500 heat pumps were sold in Germany in the first half of 2026, a 40% increase year-over-year. In Q1 2026, heat pumps reached a 48.7% share of all newly sold heating systems for the first time, ahead of gas heating. The growth is driven by federal building-efficiency subsidies (BEG) and rising awareness of the risks tied to fossil-fuel heating.

For businesses like WMK, that means more orders, more subcontractors, more job sites running in parallel at once. And that’s exactly where a familiar pattern starts: order coordination runs through spreadsheets, WhatsApp groups, and email threads, until the sheer order volume outgrows the spreadsheet. Not because those tools are bad, but because they were never built for coordinated processes across multiple roles (internal team, subcontractors, field technicians, project leads).

Where spreadsheets and generic tools stop being enough

The honest answer to “custom software or off-the-shelf SaaS?” is rarely a blanket “it depends” without actually breaking it down. In our project experience, a custom solution typically pays off when at least two of these three hold true:

• The core process isn’t generic to the industry. Standard trade-business software handles invoicing, time tracking, and simple order lists well. Once multi-step approval flows between subcontractors, the internal team, and customers enter the picture, most off-the-shelf platforms hit their limits.
• You need multiple user roles with distinct views. A field technician needs a different view than a subcontractor, who in turn needs something different than a project lead. Mapping that cleanly in a generic SaaS product usually means expensive add-on modules or workarounds.
• You want to own your data and process long-term. With SaaS, you pay per-seat licensing year after year, and the software is never “done” being purchased. With a custom system, the business owns it outright and can extend it indefinitely without a vendor’s pricing model or roadmap getting a vote.

If only one of these holds, or none, a good off-the-shelf tool is usually the faster, cheaper choice. For WMK, all three applied, and that’s exactly why a small n8n request turned into a real software project.

Case study: how WMK digitalized its order management

Starting point

WMK was growing alongside the market and had to coordinate an increasing number of orders across a growing network of subcontractors. Internal communication ran through scattered spreadsheets and messages, with the usual consequences: duplicated work, lost information, no central view of which order was in which status.

What was built

Working in close, direct collaboration, a custom web application took shape with:

• Role-based access for WMK staff, subcontractors, field technicians, and project leads, each role with exactly the view it needs
• Auto-generated PDF reports and checklists for documenting and signing off on subcontractor work
• Filterable, searchable order lists instead of endless spreadsheets
• Automated invoice processing and email communication running in the background, no manual follow-up required

Timeline, stack, and outcome

From the first kickoff call (June 2026) to production use (August 2026), less than two months passed, no small feat for a project spanning multiple user roles, document generation, and process automation. Under the hood: Next.js 16 with React 19 and TypeScript, Supabase for the database, auth, and role-separated data access (Row Level Security), Resend for automated email, and a PDF renderer for daily reports and commissioning protocols. That tight timeline was possible through short feedback loops: no months-long requirements document, just direct alignment with the team, iterative delivery, and fast decisions.

Today, more than twelve WMK employees use the tool nearly daily to coordinate orders centrally and cleanly document subcontractor sign-offs. And the collaboration doesn’t end with this project: the next phase extends the existing system to cover further processes that previously ran through individual SaaS tools or spreadsheets. For the full technical deep-dive, see our WMK Auftragsportal project case study (German only).

What a project like this realistically costs and how long it takes

Market analyses for comparable systems in the German-speaking market, with a role model, inventory module, or subcontractor management, typically assume 3 to 6 months of runtime and a high five- to low six-figure budget when a classic team of UX, frontend, backend, and project management builds it. That matches the ranges we calculate ourselves for classically staffed teams, see our post on MVP costs in 2026: €40,000–90,000 for a project with several integrations, often more.

WMK shows why that number isn’t the only reality anymore. A focused core process, a manageable number of user roles, and a generalist who handles frontend, backend, and automation in one hand with AI-assisted development, all of that noticeably shortens both timeline and budget without sacrificing quality or scope. For exactly how that adds up for a specific project, including current Baden-Württemberg funding like the Innovationsgutschein, we walk through it transparently in the MVP cost post.

One caveat worth setting expectations on: this model works excellently for tightly scoped core processes like WMK’s. Highly complex systems spanning dozens of teams or strict compliance requirements still need a larger team.

Who custom order-management software makes sense for

A short, honest checklist before committing to this path:

• Your business coordinates multiple subcontractors or user roles with different views into the same orders
• Spreadsheets or WhatsApp groups are your central coordination channel, and the error rate climbs noticeably with order volume
• Standard trade-business software doesn’t cover your core processes without expensive add-on modules or workarounds
• You’re growing (like many businesses in the current heat pump, HVAC, and solar market) and want processes that scale with the business instead of needing to be re-bought in two years

If that sounds like your business, a no-obligation initial conversation is usually worth it, where we honestly assess together whether a custom solution or good off-the-shelf software is the better path. We don’t sell projects that don’t pencil out.

Frequently Asked Questions

Does custom software make sense for smaller trade businesses too?

It depends less on company size than on the process itself. A small business with a simple, generic workflow is often better served by good off-the-shelf software. Once multiple roles (internal team, subcontractors, customers) need coordinating, the math shifts quickly toward a custom solution, regardless of headcount.

What if we already use trade-business software?

Many projects start exactly there: an existing tool covers basics like invoicing or time tracking, but not the specific subcontractor coordination process. In those cases, we often build a lean, complementary solution that connects cleanly to existing systems instead of replacing everything.

How long does a comparable project take at TAISC?

For a focused core process with a clearly scoped feature set, like the WMK case, we realistically plan 6 to 10 weeks from kickoff to production go-live. With multiple integrations or more complex approval flows, that can extend, we clarify that in the initial conversation.

Roughly what does a project like WMK's cost?

A blanket number would be dishonest without knowing the actual feature scope. For context: classically staffed teams typically budget €40,000–90,000 for comparable systems with a role model and subcontractor management. Our estimate for a focused scope regularly lands well below that, details and an interactive calculator are in our MVP costs 2026 post.

Is there state funding available for a project like this?

For companies in Baden-Württemberg, the Innovationsgutschein BW voucher may apply, provided the project involves genuine technical novelty rather than pure standard implementation. A current overview of the programs (as of 2026) is in our post on MVP costs and funding.

Conclusion

A small n8n request turned into an order- and subcontractor-management tool at WMK within two months, one that more than twelve employees now use daily. This isn’t a one-off, it’s a pattern we see repeatedly among growing trade and installation businesses: spreadsheets and WhatsApp carry you up to a certain order volume, past that, a custom solution pays off once the process is genuinely business-specific.

If you’re wondering whether your business has reached that point: let’s talk, no obligation, and we’ll honestly assess together whether a custom solution is worth it for you.