Short answer: can you add underfloor heating in a renovation?
Yes, in almost any flat or house, but the floor will rise. A water-based system with insulation and screed adds roughly 6 to 10 cm including the floor finish, low-profile systems about 2 to 3 cm, and an electric mat under tiles a few millimetres on top of the adhesive. The exact figure depends on the system you choose and the manufacturer’s data sheet.
That leads to the main rule: underfloor heating is decided at the design stage, before doors, kitchen and flooring are ordered. If it comes up after demolition, drawings and some orders have to be redone.
Where those centimetres show up
A higher floor affects everything that meets it. Internal doors have to be made for the new floor level. The threshold of the balcony door in an Eixample flat ends up lower relative to the floor, which is a leak risk when rain comes in sideways. The junction with a room that is not being renovated turns into a step or a small ramp.
In the kitchen, the extra height comes out of the space under the worktop. Integrated dishwashers and ovens have fixed installation dimensions, and the plinth may no longer work. In a duplex the first or last stair riser changes height. In older buildings with ceilings over three metres, headroom is rarely the issue; in flats from the 1970s and 80s with lower ceilings it needs checking separately.
Will the floor structure take it?
Screed is heavy. Many older Barcelona buildings have floors built on timber or steel joists with infill, and adding load across the whole flat is a question for a structural technician, not something to judge by eye on site. If the margin is tight, there are lighter options: dry systems with thin spreader plates, or a thinner anhydrite self-levelling screed.
Think about the neighbours below as well. The insulation layer under the pipes reduces impact noise, which is an argument for a complete system rather than the thinnest one available.
Where the heat comes from: water or electric
A water-based floor needs a heat source. It works best with an air-source heat pump, known in Spain as aerotermia: the low water temperature in the circuit is exactly what underfloor heating wants. A condensing gas boiler also works. The heat pump’s outdoor unit goes on a terrace, roof or façade, and that brings in the rules of the comunidad de propietarios and, in protected buildings, façade restrictions.
If the building has central heating, connecting underfloor heating to the shared circuit has to be studied with an engineer and the comunidad: heat metering, hydraulic balancing and the neighbours’ agreement. Sometimes the sensible answer is to drop the water option.
Electric underfloor heating needs less building work and costs less up front, but uses more energy. For a bathroom where it runs in the morning and evening, it makes sense. For a whole home it should be compared with a water system on several years of bills.
With a heat pump, the floor can also cool slightly in summer. Given Barcelona’s humid summers, that requires dew-point control, or condensation will form on the floor. It does not replace air conditioning that dehumidifies.
Which floor finishes are compatible
Porcelain tile and stone transfer heat best. Engineered wood works if the manufacturer explicitly approves it for underfloor heating, usually fully bonded to the screed. Solid wood and thick finishes perform worse and react more to swings in humidity and temperature. Vinyl floors have a maximum surface temperature stated in their data sheet.
If you want herringbone parquet like the one in the Urgel flat in the Eixample, the answer is an engineered herringbone approved by the manufacturer, not giving up underfloor heating. Choosing flooring is covered in a separate guide.
Sequence of work and costly mistakes
First come the circuit layout room by room and the position of the manifold. The manifold goes in an accessible cupboard or recess, because you will need to get to it again. Pipes are not laid under kitchen units, fitted wardrobes or the bath, where the heat would simply be wasted.
Before the screed is poured, the pipes are pressure-tested and the layout is photographed with reference to the walls. Five years later, those photos will save you from drilling through a pipe. The first start-up is gradual, following the screed manufacturer’s protocol, not full power on handover day. And fit a thermostat in every room: a bedroom and a living room do not need the same temperature.
What it costs and what to send us
We do not price underfloor heating in isolation from the project, because the cost depends on the area, the system, the heat source and what happens to the floor anyway. In a full renovation it is part of the quote within our tiers, from €1,000/m² at Basic level excluding VAT, and the exact scope is set after a site visit and measurements.
Send us the floor plan, the heating you have now and the floor finish you would like. We reply within an hour and will tell you which questions need answering before the design starts.