Illustration generated for this guide. It does not represent a property for sale.
Original ComparImmo illustration: a conceptual map, not geographical evidence.
Start with the correct plot
A spotless living room and a freshly painted basement do not answer the question of flood exposure. Before an offer, identify the exact plot, buildings and access points. Searching only by street name can lead you to the wrong location. Save the cadastral reference, the consultation date and a copy of the map. This initial record helps you ask specific questions about the property, rather than relying on a broad reassurance that the neighbourhood is quiet or the house looks well maintained.
What the Walloon map tells you
The official hazard map distinguishes flooding from a watercourse and surface runoff. It provides information about possible exposure, rather than an individual home’s damage history. Checking a map and looking for evidence of previous damage are therefore different tasks. The SPW link below leads to the reference tool and its explanation. Record the legend you consulted. A colour glimpsed on a commercial screenshot does not amount to a careful reading of the property file. Keep the precise location covered by your check.
Official SPW flood hazard map and explanation
Prepare your next step: Read a property file with a notebook of questions
Ask the seller for written answers
Prepare a message with the exact address and concrete questions: has water entered the property, when did it happen, which rooms were affected, and what work followed? Ask for available supporting documents without assuming that every record exists. A painting invoice alone does not explain how a moisture problem was addressed. Keep replies beside their supporting evidence. If an answer remains vague, include that uncertainty in your comparison rather than replacing the missing information with an encouraging assumption.
Visit the less photogenic spaces
Ask to see the basement, garage, low access points and rooms containing equipment. Record visible marks with the owner’s permission. A stain, smell or recently replaced finish deserves an explanation, but does not let you diagnose its cause yourself. Have a qualified professional inspect the property when a technical doubt remains. Your visit is a way to gather observations and answers, not an improvised building survey. Note where each observation was made so a specialist can understand the question later.
Check insurance before setting your budget
Give an insurer the address, intended use and information you have gathered. Request a written proposal specifying cover, possible exclusions, excesses and conditions for this property. Insurance mentioned by the seller is not an offer made to you. Discuss any planned alterations with both the insurer and municipality. Do not infer from a map that a project will receive permission or that a policy will be accepted. Those answers need to come from the relevant parties and belong in your decision file.
Compare using a documented scenario
Fictional example: you are choosing between a cheaper house with an incomplete basement history and a more expensive home with better documentation. A useful table contains more than the two asking prices. Add outstanding checks, quotes actually received, insurance responses and constraints on your timetable. Do not automatically assign a discount or repair cost to the first property. Without an inspection or quote, those figures would be assumptions and should remain labelled as such. The comparison should show where evidence is still needed.
Use ComparImmo within the limits of the document
You can analyse a readable PDF containing useful information from your file in ComparImmo. Review the summary, quoted passages and missing information, then compare your analyses using consistent criteria. The report does not visit basements or automatically verify an official map. Keep your own reference file for additional documents. After buying, document organisation becomes a recurring task. The Proprioo guide linked below complements this stage with a filing method, helping you retain the answers and records collected before the purchase.
Identify what still needs confirmation
Before committing, discuss your record with the notary and relevant professionals. Separate what you observed, what the seller stated and what a document confirms. If an unanswered question could change your decision or financing, seek an answer before treating the file as complete. This method concerns Wallonia. For a property in Brussels or Flanders, consult the tools and rules of that region instead of transferring a Walloon legend or conclusion. Keep the date of your checks so information can be revisited.
Sources and references
ComparImmo editorial team. Sources checked on 4 October 2026. Check the rules for the region and your circumstances before making a commitment.