Guide

Coastal windows: salt, wind and storms on the seafront

A seafront flat or villa asks three things of its windows. They must resist salt, resist wind at height and stay dry in the autumn storms. The data sheets answer some of this and leave some of it open. This guide shows what each data sheet states, and what to ask for in writing.

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Last reviewed: 5 October 2026

For coastal windows, check three things on the data sheet. First, the outside finish and the hardware, because salt attacks metal, not uPVC. Second, the wind class under EN 12210, which matters more on high floors. Third, the watertightness class under EN 12208, and how the threshold drains in the autumn storms.

What the data sheets say

Coastal-relevant data from the public data sheets of each system
System	Outside finish and salt	Wind (EN 12210)	Water (EN 12208)
Kömmerling PremiDoor 76 / Lux (uPVC lift and slide)	uPVC, white or foil. No marine statement.	Up to C5 on the Spanish data sheet (test size not stated). Up to C1/B2 in the German planning documents	9A
Kömmerling AluNext and AluClip Zero (alu-clad uPVC windows)	Aluminium cover. No coating seal or marine statement.	C5	9A
Cortizo 4700 (aluminium, lift and slide version)	Qualicoat over 60 µm, or anodising class 15	C2 (tested at 4.00 × 2.50 m)	7A
Cortizo 4700 (aluminium, in-line version)	Same finishes	C5 (tested at 1.80 × 2.20 m)	7A
Cortizo COR VISION (aluminium, minimal sliding)	Same finishes	C5 (tested at 1.23 × 1.55 m)	7A

Sources: Kömmerling data sheets for PremiDoor76 (2023), AluNext (2023) and AluClip Zero (2022); Kömmerling Planungsunterlagen 2026, pp. 100 and 102; Cortizo data sheets for 4700 and COR VISION (March 2025). Checked on 5 October 2026.

Salt: it attacks metal, not uPVC

Salt in the sea air does nothing to a uPVC profile. It does not corrode it and it does not fade it. Glass is not affected either; the salt stays on the surface and washes off.

Salt attacks metal: hardware, screws, locking points and any visible metal part. On aluminium frames, it attacks the coating where it is damaged.

Spain’s structural code (Código Estructural) gives examples for steel. It lists coastal areas with high salinity under its very high corrosivity class, also called C5. That is a corrosion class, not the wind class in the table above. The code gives no map by town.

What the manufacturers declare about finishes

Kömmerling makes no marine or coastal statement on its public data sheets. That includes the aluminium covers of its alu-clad uPVC windows. We do not claim one for them.

Cortizo says its powder coating carries the Qualicoat Seaside label. It says this at company level, on its coatings page, not on each system data sheet.

Cortizo’s system data sheets state powder coating to the Qualicoat label, over 60 microns (µm). For anodising, they state class 15 as standard, with classes 20 and 25 possible.

So for aluminium, ask which finish is quoted: coating with the Seaside label, or anodising of a stated class. Ask for it in writing.

Hardware: no class we can quote

EN 1670 grades the corrosion resistance of window hardware. No public data sheet for these systems states an EN 1670 grade for its hardware.

So we do not quote one. We fit hardware suited to a salty environment, and we tell you how to care for it.

Hardware care on the seafront

Most problems near the sea come from sand in the track and salt on the hardware. This routine prevents most of them:

Vacuum the sliding track two or three times a year. Never grease the track: grease holds sand, and the rollers grind it.
Rinse the frame and the hardware with fresh water two or three times a year if you are on the seafront.
Lubricate the hardware and the lift mechanism of a lift and slide door once a year, with a spray made for window hardware.
Wash the frame and the seals with water and neutral soap twice a year.
Do all of this before you close the home for the season, not when you come back.

If a sash becomes hard to move, it may need adjusting, not oil. Ask us before you force it.

Wind and height: towers in Benidorm

Wind load on a façade grows with height and with open exposure to the sea. A flat on the 20th floor of a seafront tower in Benidorm faces more wind than a villa in a garden in Javea.

The Spanish building code (CTE DB-SE-AE) puts the coast of Alicante, from Alicante city to Cabo de la Nao, in wind zone B. It treats the sea edge, with at least 5 km of open water, as the most exposed type of site.

For that type of site, its exposure coefficient rises from 2.4 at 3 m above ground to 3.7 at 30 m. Above 30 m it is calculated with the formulas in annex D, up to 200 m. The exact load on your façade is a calculation for each building.

Reading the wind class: C5 against C2

Windows and doors are tested for wind under EN 12210. The number rises with the test pressure the sample withstood. The size of the sample matters as much as the class.

The Spanish data sheet for PremiDoor 76 states wind class “up to C5”. It does not state the test size. Kömmerling’s German planning documents (Planungsunterlagen 2026) state “up to C1/B2” for the same door. Ask for the wind class in writing, for the actual size of your door.

The Cortizo 4700 in its lift and slide version reached C2, tested as a two-leaf door of 4.00 × 2.50 m. The same system in its in-line version reached C5, but tested at 1.80 × 2.20 m.

COR VISION, a minimal aluminium slider with a 20 mm meeting rail, reached C5 on a sample of 1.23 × 1.55 m. That is much smaller than the doors it is sold for. Ask for the test size whenever a wind class is quoted.

Other high-rise points

Getting the leaves up. A lift and slide leaf can weigh up to 400 kg. If it does not fit in the lift, it goes up from outside with a crane or hoist.
Cleaning from inside. In homes, glazing more than 6 m above the ground must be cleanable from inside (CTE DB-SUA 1, section 5). Plan the fixed panes with that in mind.
Safety glass. Glazed doors need laminated or toughened glass (CTE DB-SUA 2, section 1.3.3). The required impact class also depends on the drop on each side of the glass.
The community. Façade changes, cranes and work hours depend on the community of owners. Ask the community administrator first.

Autumn storms: gota fría and DANA

Rain here is scarce but it arrives in bursts. The AEMET station in Alicante records about 311 mm a year. September (56 mm) and October (47 mm) are the wettest months, in the 1981–2010 normals.

Spanish forecasters call many of these storms a DANA, an isolated upper-level low. Many people still say gota fría. AEMET notes that not every DANA brings heavy rain.

The wind that pushes the rain against the façade is often the easterly wind people here call levante. A seafront façade on a high floor gets wet from top to bottom, not only at the sill.

Watertightness 9A and the threshold

The PremiDoor 76 states watertightness class 9A under EN 12208. The Cortizo sliders in the table state 7A. In EN 12208, a higher number means the sample stayed watertight at a higher test pressure.

Kömmerling adds that other classes are possible depending on size. A class is a laboratory result for the product. On site, the threshold, the floor and the fitting decide whether water gets in.

The PremiDoor 76 has three thresholds. Flush, set 50 mm into the floor; standard, 13 mm above the floor; and renovation, 25 mm. The data sheet gives one class for the system and does not say which threshold was tested.

A flush threshold on an open terrace needs the terrace to slope away from the door, and a drainage channel in front. Without them, water collects at the door. See why windows leak in the autumn storms.

What we will not promise

That any frame needs no care by the sea. Hardware near salt needs rinsing and lubricating.

A marine certificate that the manufacturer does not publish.

That a wind or water class covers your door if it is bigger than the tested sample.

That a flush threshold stays dry on a terrace that does not drain.

In short

Tu Ventana Costa Blanca, the Benidorm office of Tu Ventana Madrid, fits windows and lift and slide doors in seafront homes and towers on the Costa Blanca. They are made to measure with Kömmerling profiles and fitted by its own team. The Spanish PremiDoor 76 data sheet states air class 4 and water class 9A. Eduardo answers in English within 24 hours.

For the lift and slide doors themselves, see lift and slide doors. For what drives the price, read what lift and slide doors cost. For glass, read glass for the Spanish sun.

Sources

A seafront flat or a high floor?

Tell us the town, the floor and which way the façade faces. Eduardo replies in English on WhatsApp, 9:00–20:00 Spain time (8:00–19:00 UK time). Ask for a quote.

Get a free quote WhatsApp Eduardo Call +34 865 443 637

Eduardo answers in English on WhatsApp, 9:00–20:00 Spain time (8:00–19:00 UK time).

Questions we are asked

Questions about windows by the sea

Last reviewed: 5 October 2026

Which type of sliding doors are better, aluminium or uPVC?

By the sea, salt does not attack uPVC, while aluminium relies on its coating or anodising. Aluminium has narrower frames. The uPVC PremiDoor 76 states water 9A. For wind, its Spanish data sheet states up to C5 and Kömmerling’s German planning documents up to C1/B2. The Cortizo 4700 lift and slide states C2 and 7A.

What are the disadvantages of aluminium windows?

Near the sea, an aluminium frame depends on its finish. Ask for the coating label or the anodising class in writing. Cortizo states Qualicoat over 60 µm and anodising class 15 on its system data sheets.

What are the disadvantages of uPVC windows?

uPVC frames are wider than minimal aluminium ones: the PremiDoor 76 meeting rail is 100 mm, against 20 mm on COR VISION. Kömmerling also makes no marine statement, although salt does not attack uPVC itself.

What are common problems with sliding doors?

By the sea, sand in the track and salt on the hardware. Vacuum the track, never grease it, rinse the hardware with fresh water and lubricate it once a year. Water at the threshold usually comes from a terrace that does not drain.

Is aluclad better than uPVC?

Alu-clad uPVC is a uPVC window with an aluminium cover outside, for the look of aluminium. Kömmerling’s data sheets give its AluNext and AluClip Zero windows wind class C5, water 9A and air class 4. It publishes no marine statement for the cover.