In short: where the line is
Inside a balcony or terrace you can usually change the flooring, lighting, sockets, furniture and plants freely. Anything visible from the street that alters the facade — railings, glazing, awnings, colour, the doors and windows opening onto it — needs the consent of the comunidad de propietarios and often a council procedure as well.
A balcony is part of the building's facade even if only you use it. So the question of whether something is allowed is not settled between you and your contractor, but in three places: the community's bylaws, the planning rules for that address and, if the building is protected, the heritage catalogue.
What is usually up to you
A new floor finish, as long as it does not change the level or cover the drains. Outdoor sockets and lighting, provided the circuit comes from your own board and is installed with protection suitable for a wet area. Built-in benches, planters or light pergolas within the perimeter, as long as they do not project beyond the railing or read from the street as a new facade element. Furniture, textiles and plants.
Even here there is a caveat: large soil-filled planters on a cantilevered Eixample balcony put load on a slab that is a hundred years old. Heavy pieces go against the building wall, not at the edge, and if the slab looks doubtful a technician is consulted.
Floor and waterproofing: the most common mistake
The most expensive mistake on a terrace is laying new tiles over the old ones. The floor rises by two or three centimetres, water starts to sit at the balcony door and the fall to the drain is lost. After one winter the water finds a way under the tiles and shows up on the ceiling of the neighbour below. The repair then includes their ceiling, and the conversation goes through the property manager.
The right order: strip back to the screed, check falls and the drain, lay the waterproofing turned up the walls and under the threshold, run a water test and only then tile. On a terrace above someone's home, the waterproofing is often treated as a common element, in which case replacing it is agreed with the comunidad. Find this out before work starts.
Railings, awnings, colour: the look of the facade
Railings are part of the facade. Replacing wrought iron with glass, raising the height or repainting in a different colour is not possible without the comunidad's agreement, even if the old railing has rusted. Repairing it while keeping the design and colour is usually far simpler than replacing it.
Awnings are the same: in many buildings the bylaws or a meeting resolution set the fabric type and colour so the facade stays uniform. Before ordering an awning, ask the property manager whether such a resolution exists. If the building is listed, the requirements are stricter; see the article on renovating in a protected building.
Glazing and merging with the room
Glazing in a balcony or removing the wall between terrace and living room is the most common request and the hardest. An enclosed balcony becomes additional living area, which is governed by the planning scheme. Glazing also changes the look of the facade and almost always needs a meeting resolution. Only the ayuntamiento can answer for a specific address, and it is worth getting that answer before spending money on design.
Taking out the wall under a balcony door affects the facade's structure. That is work under a technician's project, with the comunidad's consent and the right type of licencia de obras. If enclosure is not possible, large slim-framed sliding doors and the same flooring inside and out give a similar effect.
What to do, in order
First, find out whether the building is listed. Then ask the property manager for the bylaws and any meeting resolutions on the facade, awnings and glazing. Next, describe the works in writing and agree with your contractor what type of council procedure applies. Only then order materials.
In a detached house in Castelldefels or the Garraf there is often no comunidad and everything is simpler, but a terrace over living space is even more critical: the leak ends up in your own bedroom. We start every terrace job by checking the drain, the falls and the threshold.