Patio vs Balcony Doors Know the differences

The question "what are the differences between patio doors and balcony doors" arises every construction season among clients planning an exit to the garden or access to a balcony on an upper floor. Both solutions appear similar at first glance – large glazing, aluminum or PVC frame – but differ in threshold construction, opening mechanism, sash dimensions, and insulation parameters. Below, we describe the differences step by step to facilitate a choice aligned with real application.

Definitions: what are patio doors and balcony doors formally?

Patio doors are designed for easy, frequent access at ground level or terrace – their main feature is a low threshold and sliding mechanism allowing a wide passage, facilitating the movement of garden furniture or a stroller. Balcony doors, on the other hand, serve access to a balcony, which is usually higher than the room floor level – hence the more common higher threshold and narrower sash, suited to the narrower opening typical for balconies in multi-family buildings.

In the BUDVAR catalog, these two product groups are separated: PVC patio doors include T-Slide HST and PSK Doors, while in aluminum – MB-Skyline Type R and MB-77HS. PVC balcony doors include models T-Classic, T-Classic Plus, T-Classic Slim, T-Comfort, T-Energy, and T-Perfekt, while in aluminum – MB-79N, MB-79N US, Ecofutural, and Ecofutural OC. This catalog division reflects real structural differences, not just marketing nomenclature. Full acoustic parameters of individual models are available in the product sheets.

Dimensions and threshold – key criteria for differentiation

The most practical difference concerns the threshold. Patio doors are most often designed with a low or almost floor-level threshold – a solution appreciated by the elderly, families with young children, and where easy rolling of furniture or garden equipment is important. Balcony doors usually maintain a higher threshold, partly due to the building's structural reasons (waterproofing, water drainage from the balcony) and partly because a balcony does not require the same freedom of movement as a terrace.

The width of the opening is the second criterion. Patio doors, especially in sliding variants, allow for much wider glazing than typical hinged or tilt-and-turn balcony doors, as the sliding mechanism does not require the sash to swing inward. When designing the opening, it is worth first determining how much space is available in the room for sash movement – this decides whether it is sensible to consider hinged doors in a given location.

Construction and mechanisms: hinged, PSK, HST

Hinged doors are the simplest mechanism – the sash opens on hinges, inward or outward. They work well with narrower openings, typical for balconies, and where there is no space for a sliding track. The downside is the need to leave free space for sash movement, which limits furniture placement near the opening.

Tilt-and-slide doors (PSK) combine the tilt function (ventilation without full opening) with sash sliding along the wall. This is an intermediate solution – it does not require as much space as hinged doors, yet does not offer as wide a passage as the HST system. In the BUDVAR catalog, it is represented by the PSK Doors model.

Lift-and-slide doors (HST) are a construction where the sash is lifted on rollers and moved almost effortlessly, even with large and heavy glass panes. HST is best suited for wide terrace openings, where maximum glazing and comfortable operation without struggling with the sash are desired. In BUDVAR's offer, this is the T-Slide HST model, available in PVC.

Thermal insulation and material: PVC or aluminum

The Uw parameter describes the thermal insulation of the entire window-door or sliding construction – the lower the value, the better the insulation. The Ud parameter applies to entrance doors. For balcony and patio doors, we use Uw – these two metrics are not interchangeable and should not be compared when choosing a product.

From the BUDVAR catalog: patio doors T-Slide HST have a Uw of 0.74 W/(m²·K), and PSK Doors – Uw of 0.48 W/(m²·K). For comparison, in aluminum entrance doors (not patio or balcony), we find Ud values: MB-104 Passive – 0.72 W/(m²·K), Genesis – 0.91 W/(m²·K), Imperial – 1.4 W/(m²·K). These numbers pertain to specific BUDVAR models and should not be transferred to other constructions or directly compared with balcony or patio door parameters without checking if the same metric is being discussed.

Material – PVC or aluminum – affects the frame's rigidity with large glazing and the profile's appearance. Aluminum allows for slimmer frames while maintaining load-bearing capacity, which can be important for very wide terrace constructions. PVC remains a universal solution, suitable for both balcony and patio doors of moderate width.

Mechanisms in practice: comparison of hinged vs PSK vs HST

Hinged doors are suitable for narrow openings, where simplicity of mechanism and lower budget matter, but they require free space for sash movement and are not suitable for very wide glazing. PSK doors are an intermediate solution: lower space requirements for sliding than inward-opening hinged doors, moderate comfort of operation, a good compromise for medium-width openings. HST doors handle the widest openings, offer the highest sliding comfort even with heavy panes, but require careful installation of the track.

Selection criteria: terrace or balcony

When choosing doors for a terrace, check: if the opening has at least 90 cm of passage width (minimum for comfortable and accessible passage, also with a stroller), what the planned ground slope at the threshold is (usually 1.5–2% for water drainage from the building), if the location is exposed to strong winds (higher floors or open plots require a more robust locking mechanism), if furniture or built-in elements are planned in front of the opening (this limits the choice of hinged doors), and what opening direction is required relative to the room layout. Remember that a low threshold in the HST system requires appropriate preparation of floor layers and linear drainage – more on this in the guide's further sections.

When choosing doors for a balcony, it is crucial to check the opening width in the wall's light – balconies in multi-family buildings often have narrower openings than terraces, which naturally directs the choice towards hinged or PSK doors instead of HST. It is also worth determining whether the balcony has sufficient load-bearing capacity and whether the cooperative or community allows changing the type of joinery on the facade.

Common mistakes when ordering

The first common mistake is mixing Ud and Uw metrics when comparing offers – these values are not interchangeable, and comparing them directly leads to erroneous conclusions about actual insulation. The second mistake is comparing technical parameters given for different reference dimensions of testing – the same model with a different sash size may have a different result, so it is worth asking for the parameter for the specific planned product dimension.

The third mistake is overlooking the threshold issue when ordering patio doors for the elderly or those with limited mobility – a low threshold needs to be consciously ordered, as it is not default in all variants. The fourth mistake is choosing a mechanism without checking the real space for sash movement or sliding track, which ends in a collision with furniture or inability to fully open.