What does alterações à obra mean in Portugal?
Changes to the agreed plan need the owner's authorisation: the contractor may not make them alone. The owner may demand changes worth up to one fifth of the agreed price, provided the nature of the work does not change.
- Rests on
- Código Civil, art. 1214.º to art. 1216.º
- Law
- Código Civil (Decreto-Lei n.º 47344/66), consolidated text updated to Lei n.º 29/2026
- Official text
- pgdlisboa.pt/leis/lei_mostra_articulado.php?ficha=1201&ar...
- Sources
- pgdlisboa.pt/leis/lei_mostra_articulado.php?ficha=1201&ar...
- Checked
- 2026-11-05
What it means for the owner
- Unauthorised changes make the work defective; if the owner accepts it as built, no extra price or compensation is owed (art. 1214.º n.º 2).
- With a global price, a change not authorised in writing with the price increase leaves the contractor only a claim for the owner's enrichment (art. 1214.º n.º 3).
- Changes the owner demands give the contractor a price increase and more time; savings reduce the price (art. 1216.º n.º 2 and n.º 3).
- If changes forced by third-party rights or technical rules raise the price by more than 20%, the contractor may terminate and claim fair compensation (art. 1215.º).
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