Section 5 · Cost of not inspecting
What Illegal Construction Actually Costs to Fix
There is no fixed price for legalisation. Costs depend on the type, scale, and location of the works — and some cannot be legalised at all.
Inspect OS PROPERTY INSPECTION
Simplex Safe inspection
€450
Certified engineer · 47 checkpoints · Bilingual report in 48h
Average ROI: 2,756%
VS
Average hidden cost — post-purchase
€12,400
Average discovered after escritura · Up to €250,000 for major unlicensed structures
Legalisation cost by infraction type — post-escritura (buyer liability)
Simplex Safe inspection
€450
Enclosed balcony / marquise
€5k – €50k
Change of use (basement / attic)
€10k – €80k
Non-legalisable — demolition order
€10k – €80k
Unapproved structural modification
€15k – €150k
Additional floor construction
€30k – €250k
⚠️
Some irregularities cannot be legalised at all
Works violating the PDM or current safety standards may result in a mandatory demolition order at the buyer's expense. The Câmara Municipal has up to 10 years to act.