Renovating near the sea: boundaries and the Ley de Costas
By Ross Alinari · Last checked · Editorial policy · How we check facts
A sea view does not tell you which coastal restrictions apply to a property. The Ley de Costas distinguishes public maritime-terrestrial land, the legally defined shore and several adjoining restrictions. Their position and effect need to be established from the relevant records. Before designing an extension or external alteration near the coast, identify the applicable boundary and the building’s legal history. A measurement taken from the waterline on a photograph is not an adequate substitute.
Start with the approved boundary
The deslinde is the procedure establishing the boundary of the public maritime-terrestrial domain. Article 12 addresses its approval and the participation of adjoining owners and relevant authorities. The approved boundary is a legal record; the apparent edge of a beach, a garden wall or a cadastral outline should not simply be substituted for it.
Obtain the relevant approved boundary documents and identify the property accurately against them. A viewer can help locate information, but a screenshot should be accompanied by the underlying reference and an understanding of what the displayed lines represent. Keep the date of the check and any uncertainty about the alignment visible. If the property is close to a boundary or the record is difficult to interpret, obtain a property-specific assessment before treating a design option as available. This guide does not claim to have completed a parcel-level viewer check for every coastal neighbourhood on the site.
Source: Ley de Costas arts. 11–13.
Understand the protection easement
Article 23 establishes a general protection strip extending 100 metres inland from the inner limit of the shore, with the modifications provided by the law. Article 25 restricts uses within that strip, including buildings intended for residence or habitation, while providing the specified framework for permitted and exceptional activities. These provisions must be read with the applicable transitional rules and the property’s circumstances.
Do not interpret the general distance as a universal answer for every existing urban building. Identify the line from which it is measured and whether a relevant transitional provision applies. Ask the technician to distinguish the current building from a proposed increase in volume, height or footprint. An owner’s wish to improve a home and the legal treatment of a new enclosure are different matters. Keep the planning and coastal assessments connected to the same drawing so the design is not accepted on inconsistent assumptions about the affected area.
Source: Ley de Costas arts. 23 and 25.
Check the urban transitional position
The third transitional provision addresses land classified in different ways when the coastal law entered into force, including the treatment of urban land and the relevant reduced protection width in the circumstances specified. It does not establish that every property described today as urban automatically benefits from a 20-metre strip.
The historical classification and applicable planning records therefore matter. Ask for the evidence supporting any claim that a particular transitional regime applies, including the relevant dates. A modern sales description, postal address or current cadastral label should not be used as the whole basis for that conclusion. Retain the actual record and the assessment connecting it to the proposal. If historical documents are missing, identify that gap explicitly before designing on the assumption that the more favourable distance is available. This is particularly important where a proposed extension would only work under one interpretation of the coastal position.
Source: Ley de Costas transitional provision 3.
Keep transit and access clear in the assessment
Article 27 establishes a transit strip generally six metres wide from the inner limit of the shore, with possible enlargement in difficult or dangerous areas and the specific exceptions stated there. Article 28 addresses public and free access to the sea. These restrictions serve different purposes from the protection easement and should not be merged into a single generic setback.
Mark any relevant transit or access line on the proposal and identify walls, gates, steps or stored materials that could affect it. A private garden appearance does not settle whether public passage rights apply. During planning, consider both the finished design and temporary construction arrangements. Equipment, debris storage and access for the contractor may raise questions even where the permanent works are limited. Ask which authority’s approval or conditions govern the particular arrangement and retain the answer with the construction documents. This guide gives no blanket permission to obstruct a coastal route for the convenience of building work.
Source: Ley de Costas arts. 27–28.
Investigate the history of existing structures
The fourth transitional provision distinguishes existing works according to their legal position and location. For specified existing buildings and installations, it addresses repair, improvement, consolidation and modernisation subject to conditions, including limits on increasing volume, height or area in the relevant categories. Existing construction should therefore not be assumed either freely alterable or automatically incapable of any work.
Collect the relevant original permissions, concessions or authorisations and compare them with the building as it stands. Identify later alterations separately, rather than assuming all parts share the same history. A new roof enclosure may need a different assessment from repairing an existing finish. Ask for the proposed scope to be described precisely enough to apply the relevant rule. If the documents do not establish the status of an element, keep that issue open instead of building a quotation around an assumed right to retain, enlarge or reconstruct it.
Source: Ley de Costas transitional provision 4.
Coordinate authorities and records from abroad
The coastal law addresses state, regional and municipal competences. The competent procedure for a particular intervention must be established using the current allocation of functions and the relevant property circumstances. A municipal works document should not be assumed to replace every coastal title, and a coastal document does not resolve every planning or ownership question.
For an owner abroad, maintain a schedule showing each required document, its authority, reference, conditions and relationship to the design. Ask for any uncertainty to be resolved before instructing work that depends on it. Keep approved drawings and later changes identifiable, and ensure the construction proposal follows the same scope assessed by the technical advisers. Where a boundary-viewer check has not been completed, do not describe the property as cleared merely because a general guide has been read. The useful outcome is a property-specific, documented basis for the proposed work, with outstanding matters visible before construction commitments are made.
Source: Ley de Costas arts. 110, 114 and 115.
Worked example
A coastal owner wants to enclose a terrace. The first review identifies the approved boundary, any protection and transit easements, and the terrace's existing authorisation history. The technician then assesses the proposed enclosure rather than treating it as equivalent to repairing the terrace finish. If the relevant documents are missing, that option remains unresolved. This hypothetical example establishes no permission for a named plot or neighbourhood.