Vom Dachratgeber zur digitalen Checkliste: Unbekannte Daten sauber modellieren

A construction project highlights a common issue with digital forms: a mandatory field can lead users to estimate a value even when it's unknown. For roof projects, this concerns the condition of hidden structural elements. A helpful form separates observation, speculation, and open questions. The practical starting idea comes from the Spree Dachwerk article on roof renovation.

This article translates it into a simple data structure for a digital project checklist. An unknown status in a field like unterdachIntact: false would represent an unexamined damage. An explicit status prevents this confusion: type Befund = | { status : unbekannt ; klaerungsbedarf : string } | { status : beobachtet ; beschreibung : string }; const unterdach : Befund = { status : unbekannt , klaerungsbedarf : Aufbau und Zustand vor Ort prüfen }; This is a journalistic model, not a technically verified building assessment.

It records what is known, and makes open points visible. Descriptions of moisture are not a determination of their cause. The project goal and scope are separated to be input in a checklist. A free text like "new roof" is not enough for a quotation comparison. The checklist allows desired works to be listed separately: deck cover, under-ditch, insulation, windows, drainage, and interior work.

Services whose inclusion still needs to be clarified stand in another list. Second list enumerates side works, such as access, scaffolding, dismantling and disposal. Each position has a selection like "included", "excluded" or "to be clarified". Offers are comparable only if their tasks match. Validation should clarify missing information, not invent accuracy.

For unknown roofing layers, "must be examined" is a useful answer. Automatically deriving cheap prices from such data would give a false sense of security that the data does not carry. The practical benefit of this structure is in preparation: users collect facts and questions for a conversation with a professional. The digital checklist replaces neither the stock survey nor a personalized quotation.

Source and detailed technical placement: Spree Dachwerk – Dachsanierung und Kosten. The text and code example were newly created for this publication.