What to choose for a terrace: timber, stone or porcelain?
For a Barcelona penthouse, porcelain at 20 mm on adjustable pedestals most often wins: it is light for a stone-type material, does not fear sun, needs no oiling and gives access to the waterproofing. Timber (ipe, teak, thermally modified ash) is chosen for warmth and softness underfoot, accepting upkeep. Natural stone is beautiful and cool, but heavier and more sensitive to stains and salt.
There are five criteria: heating in the sun, weight on the slab, slip resistance, access to the waterproofing and how the surface sits relative to the living room. Below, one by one. If the terrace is by the sea, salt and stainless steel fixings are added.
Which terrace floor does not get hot in summer?
Light and matt always heats less than dark and glossy. In direct sun, dark timber, composite and dark porcelain can get so hot that walking barefoot is uncomfortable, while pale limestone, pale travertine and light matt porcelain are clearly cooler. I will not give exact degrees: they depend on colour, texture, thickness and ventilation under the piece.
A raised floor on pedestals works in your favour: the air gap below cools the piece and carries heat away. For a terrace where people go barefoot, choose a light tone, a matt texture and avoid dark floors in full south sun. If the design calls for a dark tone, limit it to areas shaded by the pergola.
What is a raised floor on pedestals?
These are slabs (porcelain, stone, concrete) laid not in adhesive on screed but on adjustable plastic pedestals ranging from a couple of centimetres to several tens. Water drops through the joints and runs down the waterproofing's fall to the drain. The top stays dry and the slab stays clean.
Three advantages for a penthouse. Access: any slab can be lifted to inspect the waterproofing, the drain or cabling. Levelling: pedestals adjust, so you get a perfectly flat surface over a sloping base without removing the membrane's fall. Weight: there is no screed, so less load on the slab. One drawback: height. A slab on pedestals adds two or three centimetres that must be planned into the threshold and balustrade levels.
Teak or composite?
Teak and ipe are living materials: they change colour, silver in the sun and, if you want to keep the tone, are oiled once or twice a year. Composite (wood-plastic) is colour-stable, needs no oil, but heats more, expands and feels different underfoot. In a luxury interior the first is chosen for texture, the second where having no upkeep matters more.
If the owner visits a few months of the year, natural timber without care soon loses its look: plan a service visit or choose thermally modified species or composites. And check the fixings: hidden stainless steel A4 (316) for a seaside terrace, and ventilation under the board so water does not stand.
How do you match the terrace level with the interior?
Level is solved from the bottom up, not from the top down: add the slab height, waterproofing, fall, pedestals and finish, and compare with the interior floor level. A difference of 2 to 3 cm is acceptable and even desirable: it keeps water from entering the home. A fully flush finish is only done with linear drainage at the glass door and the waterproofing raised under the profile.
A practical device: raise the interior floor in the threshold zone with a podium, or lower the terrace if the slab allows. It is decided at the design stage together with the choice of sliding doors, because their profile height sets everything else. A terrace floor cannot be chosen separately from the doors and the living-room finish.
Slip resistance, weight and upkeep: what to check before ordering
Slip resistance: for exteriors, ask the maker for the slip-resistance class; for wet exterior surfaces the highest (class 3) is usually required, especially around a pool and on slopes. Smooth polished stone on a terrace is dangerous after rain.
Weight: orders of magnitude per square metre: 20 mm porcelain about 45 to 50 kg; 30 mm natural stone about 80 kg or more; timber decking with joists 25 to 35 kg; composite around 20 to 25 kg. These are guides: take exact figures from the manufacturer and check them against the slab calculation. Upkeep: porcelain is washed with water; timber is oiled once or twice a year; stone is sealed and kept away from acids. And always ask for a 1 m2 sample on the terrace for a couple of weeks.
Where to start and how BCN YARD can help
Start with three data points: the load on the slab, the waterproofing level and the threshold height. Then choose finish, tone and texture, and leave samples on the terrace for two weeks to see how they behave in sun and after rain.
BCN YARD handles terrace and penthouse renovations in Russian and Spanish, with one person responsible for the site. We start with a visit and measurements and continue with a phased estimate in which the floor, pedestals and waterproofing are coordinated by level with the windows and the living-room finish.
Frequently asked questions
Can tile be glued to the terrace with adhesive?
It can, but gluing onto a screed over the waterproofing has drawbacks: weight, cracked joints from temperature movement and no access to the membrane. If you want a rigid finish you need movement joints and a flexible adhesive. On a penthouse pedestals are usually the better choice, because any future leak can be repaired without breaking up the floor.
What porcelain thickness does a terrace need?
For laying on pedestals, 20 mm slabs are used: they carry furniture and people without a continuous base. Thin 6 to 10 mm slabs go on a rigid substrate and are not suitable on pedestals. For concentrated loads, such as a hot tub, the load is calculated separately.
Do slabs on pedestals need a fall?
Slabs lie level and the fall stays in the waterproofing below (usually 1.5 to 2 percent). The pedestals compensate for the difference and water under the slabs runs to the drain. That is why the pedestal height and adjustment range are decided before ordering.