How much can I build on my plot in Portugal?

Since 2019, the terms used in Portuguese municipal plans have official definitions in Regulatory Decree 5/2019 (Decreto Regulamentar n.º 5/2019), which sets the technical vocabulary for spatial planning and urban development. Many PDMs were approved earlier and still use older words such as "índice de construção", "índice de implantação" or "área bruta de construção". Always read the definitions in your plan's regulations, usually in the first articles.

The table lists each official term, the names you will still see in PDMs and listings, the formula and what counts toward it.

The floor area ratio (Iu) is the total floor area divided by the land area the ratio refers to. An Iu of 0.5 allows 0.5 m² of floor area for every m² of land; an Iu of 1.2 allows more floor area than the plot itself, spread over several stories. To get the maximum, multiply the ratio by the land area.

What counts toward that floor area is where most mistakes happen. Under Regulatory Decree 5/2019, floor area adds up every story above and below the cota de soleira (the level of the main entrance) and only excludes attics and basements without the regulation ceiling height (pé-direito). Many PDM regulations, however, apply the ratio only above the cota de soleira, or exclude basement parking and plant rooms: read the definitions article and your category's article before doing the math.

The site coverage ratio (Io) is the percentage of the plot that buildings may cover: footprint divided by land area, times 100. With an Io of 30% on an 800 m² plot, the maximum footprint is 240 m², usually counting the house and any outbuildings together.

The footprint (área de implantação) is the polygon where the building meets the ground and includes the outer perimeter of the basement walls, so a basement larger than the ground floor increases the footprint. Some PDMs also set an impervious surface ratio, which also counts outdoor paving and driveways and can be tighter than the site coverage ratio.

Regulatory Decree 5/2019 defines two heights. Facade height (altura da fachada) runs from the cota de soleira to the top of the cornice, eave, parapet or terrace railing. Building height (altura da edificação) runs to the highest point of the building, including the roof and any volumes on it, but excluding chimneys and accessory or decorative elements. Both add the threshold elevation (elevação da soleira).

"Cércea", a word you will find in many PDMs, has no definition sheet of its own in Regulatory Decree 5/2019: the note on the building height sheet says the term fits that height and should not be used for facade height. The RJUE (Portugal's building and development permit law) and many PDMs still use "cércea", sometimes meaning facade height, so check how your plan defines it.

There is no official definition of "number of stories" either. Many PDMs set the height in meters and in stories at the same time, and state whether basements, attics or setback top floors count. A 7 m facade height generally allows two stories above ground, but the regulations decide.

A setback (afastamento) is the distance between a facade and the corresponding boundary of the plot: front, sides and rear. The building line (alinhamento) separates the public domain from private plots, normally along the street frontage. Minimum setbacks may come from the PDM, a municipal bylaw, a subdivision permit or general rules in the Regulamento Geral das Edificações Urbanas (RGEU, the general building regulations) and the Portuguese Civil Code on distances between buildings and windows.

Setbacks define the envelope where the building can sit. On wide plots they rarely bind; on narrow or irregular plots they can become the tightest limit, as the next example shows.

The figures are hypothetical and only illustrate the method. Picture a flat rectangular plot 20 m wide and 40 m deep (800 m²), in a residential category with an Iu of 0.50, an Io of 30%, two stories above ground and setbacks of 5 m at the front, 3 m on each side and 6 m at the rear. Assume the regulations do not count the basement, there are no constraints, and every story has the same area.

Scenario A: the Iu allows 0.50 × 800 = 400 m² of floor area and the Io allows 30% × 800 = 240 m² of footprint. After setbacks, the envelope is (20 − 3 − 3) × (40 − 5 − 6) = 14 × 29 = 406 m², so the footprint stays at 240 m². Two stories of 240 m² would give 480 m², more than 400 m²: the Iu applies, and you can build 400 m², for example 240 m² on the ground floor and 160 m² upstairs.

Now change one variable at a time. On a 12 m × 40 m plot (480 m²), the Iu gives 240 m², the Io 144 m² and the envelope (12 − 6) × 29 = 174 m²; the footprint stays at 144 m², two stories would give 288 m², and the Iu applies again at 240 m². If that plot requires 4 m on each side, the envelope drops to (12 − 8) × 29 = 116 m² and two stories give 232 m²: the setbacks apply. On the 800 m² plot with a single story, the area stays at the 240 m² footprint: the height limit applies.

• Work out the maximum floor area from the Iu: ratio × land area.
• Work out the maximum footprint from the Io: percentage × land area.
• Draw the envelope left after setbacks and take the smaller of that envelope and the Io footprint.
• Multiply that footprint by the number of stories the height limit allows.
• The maximum floor area is the smaller of the Iu result and the previous step.

Under the official definition, a basement (cave) with the regulation ceiling height counts as floor area. In scenario A, if you build a 120 m² basement with the regulation ceiling height and the PDM follows that definition, 400 − 120 = 280 m² remain for the stories above ground. If the regulations only count area above the cota de soleira, you keep 400 m² above ground and add the basement.

Attics (sótãos) and basements without the regulation ceiling height are excluded. Outbuildings and garages are buildings or parts of buildings and generally count toward floor area and footprint unless the plan expressly excludes them. Under the official definition, floor area also includes covered circulation areas and covered outdoor spaces such as porches, lean-tos, balconies and covered terraces; only what the regulations expressly exclude stays out.

The ratio applies to the "land area the ratio refers to", which the plan defines. It may be the whole plot, only the part inside one category, or the area left after land is dedicated for streets and public spaces in a subdivision (loteamento). If the plot is split between two categories, each part generally follows its own category's parameters.

The same goes for REN (Reserva Ecológica Nacional, the national ecological reserve) or RAN (Reserva Agrícola Nacional, the national agricultural reserve). Suppose 160 m² of the scenario A plot is in REN. If the regulations exclude REN from the land area, the Iu gives 0.50 × 640 = 320 m²; if they do not, you keep 400 m² under the ratio, but the building must stay outside the REN area, and the remaining envelope may become the limit.

The parameters are in the regulations, not on the maps. The land-use map (planta de ordenamento) tells you the plot's category; that category's article, or an annexed table of parameters, gives the Iu, the Io, the heights and the setbacks. Read the general provisions too, where measurement rules, exceptions and the treatment of basements and parking usually sit.

If there is a plano de urbanização (PU, urbanization plan) or a plano de pormenor (PP, detailed plan) for the area, its more detailed parameters usually govern the plot. In an approved subdivision, the subdivision title sets the floor area and footprint of each lot, and municipal building bylaws may add measurement rules.

To find the right plan and article, follow the step-by-step in our guide can I build on my land in Portugal?.

On rustic land, building is the exception and PDMs usually set parameters differently: instead of a ratio, a maximum floor area, a maximum number of stories, a minimum plot size and different rules for each permitted use, such as farm-support buildings, housing tied to a farm, tourism or works on existing buildings. The figures vary widely between municipalities.

Before doing the math, confirm that the use you want is allowed. Our guide can I build on rustic land? explains the exceptions, and urban or rustic land: how to check explains how land is classified in Portugal.

When the parameters depend on interpretation, as with basements, a plot split between two categories or an area in REN, the safe route is to ask the Câmara Municipal (municipal council) through a pedido de informação prévia (PIP), a binding pre-application ruling. A simple PIP confirms feasibility and the applicable constraints, including ratios, heights (cérceas) and setbacks.

An extended PIP (RJUE article 14(2)) can set massing, footprint, height, floor area per use and number of dwellings; if it is favorable and covers every applicable item, it exempts the works from a building permit or comunicação prévia (prior notification), provided they follow what was assessed. The decision is valid for 2 years. See our complete PIP guide or ask us to prepare your PIP.

The official sources are in Portuguese. Check the version in force before preparing a notice, project or application.

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