How a Custom SaaS App Saves a Building-Services Company More Than 30 Hours Every Week

An Excel dispatch board, paper reports, WhatsApp photos – and invoices sent 18 days late. Then came an app of their own.

A building-services company in Germany's Ruhr region – 38 employees, 16 field technicians – had a problem almost every service business knows: the work in the field was excellent, but back at the office every job was done twice. Once at the customer's site, once at the desk. This is the story of how we built them a custom SaaS app that talks to their ERP and Microsoft 365 through API integrations – and gives the team back more than 30 hours every single week.

The Starting Point: A Healthy Business Drowning in Its Own Admin

The company – let's call it "Kessler Building Services" for confidentiality – maintains heating, ventilation and air-conditioning systems for housing associations, property managers and commercial clients. Maintenance contracts, breakdown service, emergency call-outs: roughly 60 to 80 jobs a week. Technically superb, financially solid – and organisationally at its limit.

The first time we sat down together, the managing director summed up his daily life in one sentence: "My technicians fix systems in record time – but the information about it takes three weeks to become an invoice." In practice, the workflow looked like this:

• Dispatching in Excel: Two dispatchers maintained a weekly planning board as a spreadsheet. Every change (and in breakdown service, everything is change) meant rebuilding the table, calling the technician, printing new job sheets. Around 10 hours a week.
• Service reports on paper: Technicians filled in carbon-copy forms, photographed them with their phones and sent them to the office via WhatsApp. There they were deciphered and typed into the ERP – about 12 hours a week, spread across three people.
• Searching instead of knowing: "When were we last at this installation? What was replaced?" – questions like these cost phone calls, binder-digging and an estimated 6 hours a week.
• Invoices after 18 days: On average, two and a half weeks passed between a job and its invoice. With a six-figure monthly service volume, that isn't just a process problem – it's a cash-flow problem.

On top of that came a quiet, expensive classic: every so often a report simply went missing – in the van, in a chat history, in a paper pile. Every lost report was a job that never got billed.

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Why Not Off-the-Shelf Software? That Was Our First Question Too

Let's be honest: if a ready-made tool solves the problem, we recommend the ready-made tool. The company had in fact trialled two field-service solutions – and dropped both. The reasons are typical for mid-size businesses:

• 80% feature bloat, 20% gap: The tools could do plenty of things nobody needed – but the details that actually mattered (maintenance contracts with customer-specific checklists, the company's own asset-numbering logic) could only be forced in with workarounds.
• Per-seat licence costs: 16 technicians plus office staff would have cost 1,200 to 2,000 euros per month depending on the vendor – permanently, with annual price increases.
• The ERP had to stay: Master data, articles and invoicing lived in the existing cloud ERP. Replacing it was off the table – the new solution had to plug in via APIs, not take over.

Exactly this constellation – a working core, individual processes, no fitting standard product – is the classic case for custom software. How to keep the budget under control in such a project is covered in our custom software pricing guide.

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The Solution: A Service Portal as a SaaS App – Built Around the Existing Systems

We developed a lean web app – internally everyone just calls it "the portal" – that sits as the central hub between the office, the technicians and the existing systems. No new ERP, no data silo: the app reads and writes its data through API integrations, keeping every record where it belongs.

Building Block 1: Job Intake Without Retyping

Fault reports arrive by phone, email or through a web form that the larger housing associations link to directly. Whatever the channel: a structured job is created in the portal. Nobody has to look up customer data, site addresses or installation history any more – they are pulled automatically through the ERP's REST API and attached to the job.

Building Block 2: A Digital Dispatch Board Instead of Excel

Dispatchers now plan jobs via drag and drop on a digital planning board. The clever part is the integration: through the Microsoft Graph API, the portal syncs jobs with the technicians' Outlook calendars – holidays, training days and appointments are visible automatically. When a job is rescheduled, the technician gets a push notification instead of a phone call.

Building Block 3: The Technician App – Offline-Capable, Because Boiler Rooms Have No Signal

The technicians use the portal as a progressive web app on their existing work phones – no app store, no new devices. They see their jobs, the complete installation history and the checklist matching the maintenance contract. The service report is created right on site: tick off the checklist, take photos, record materials, and the customer signs on the display. And because boiler rooms are notorious dead zones, all of it works offline – syncing as soon as the signal returns.

Building Block 4: From Report to Invoice – Automatic, but with Human Sign-Off

The moment the customer signs, things happen in the background that used to take days:

1. The portal generates a clean report PDF with photos, checklist and signature.
2. The report is archived in SharePoint through the Microsoft Graph API – filed per site and installation, findable and audit-proof.
3. The customer automatically receives the report by email – often before the technician has left the premises.
4. From the recorded time and materials, the portal creates a draft invoice through the ERP API.

One deliberate design decision: the invoice does not go out automatically. Accounting reviews the draft and releases it with one click. The machine does the grunt work, a human keeps control – the same principle that proved itself in our law firm case study.

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The Result After Three Months: 30+ Hours a Week – and Invoices Within 48 Hours

The following figures are the measured results of this one company – not an industry average, but a concrete individual case after three months in production.

The bottom line: more than 30 hours per week that used to disappear into retyping, rescheduling and searching – now flowing into customer care, additional maintenance contracts and finishing work on time. The side effect the managing director values most: with invoices going out after 48 hours instead of 18 days, a five-figure sum that used to sit permanently in unbilled work has vanished from the books.

Effort and running costs:

We didn't start with a big-bang project but with an MVP: after six weeks, the first version with the dispatch board and digital service reports was live – deliberately limited to the features that save time immediately. The ERP invoicing pipeline and the SharePoint archive followed in two expansion stages. The app belongs to the company: no per-seat licence fees, no annual price increases – just modest hosting and maintenance costs. Our pricing page shows what such an entry point costs (software MVP from €4,900).

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Three Things This Project Taught Us

• Integrations beat migrations. The company didn't have to give up a single existing system. The app plugs into the ERP and Microsoft 365 via APIs – so there was no data migration, no parallel operation, no weeks of training.
• The technicians decide whether it succeeds. We brought two technicians into the design from day one. The result: big buttons for gloved hands, offline mode as a must-have, a report done in under two minutes. After two weeks, nobody wanted the carbon-copy forms back.
• Start small, start at the bottleneck. Not "the one big solution", but the process that eats the most time first. The MVP paid for itself in under four months – everything after that was expansion on proven ground.

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Who a Custom SaaS App Makes Sense For

This pattern – Excel as a dispatch board, paper or WhatsApp as the reporting channel, double data entry, late invoices – is not unique to building services. We find it in electrical and plumbing companies, plant engineering, property management, inspection services and logistics. Our rule of thumb from project experience: if a team spends a double-digit number of hours per week moving information from one medium into another, a custom app with clean API integrations is almost always cheaper than three more years of muddling through – and often cheaper than the standard-software licences over the same period.

For similar results achieved with pure process automation instead of a dedicated app, see our case study on a plumbing company in NRW – sometimes that's already enough. Which route fits your business usually becomes clear within a 30-minute conversation.

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Does This Sound Familiar?

If Excel carries your dispatching, reports travel through your company as photos, and weeks pass between a job and its invoice – it's worth a conversation.

We offer a free initial consultation in which we look together at where your biggest time sink sits – and whether a custom app, an automation or simply a better process is the right answer.

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Note: this article describes an anonymised real-world case; the company name and certain details have been changed to protect the client. The time savings mentioned are the results of this specific project, not guaranteed outcomes.

About Lyron: Lyron is a consultancy for automation and custom software based near Düsseldorf/Neuss, Germany. We build web apps, internal portals and SaaS tools with clean API integrations for small and mid-size companies – and automate the processes around them.