{"id":5261,"date":"2026-11-13T19:49:47","date_gmt":"2026-11-13T18:49:47","guid":{"rendered":"https:\/\/aristofenster.eu\/window-installation-ral\/"},"modified":"2026-11-14T05:47:59","modified_gmt":"2026-11-14T04:47:59","slug":"window-installation-ral","status":"publish","type":"post","link":"https:\/\/aristofenster.eu\/en\/window-installation-ral\/","title":{"rendered":"Window Installation to RAL Standards: Why Fitting Matters as Much as the Window"},"content":{"rendered":"

Many homeowners compare profiles, glass and U-values in great detail \u2013 and underestimate the installation. Yet it is the fitting that determines whether a window actually achieves its insulation values in everyday use. Leaky joints cause draughts, heat loss and, in the worst case, mould. This is exactly what RAL installation<\/strong> is designed to prevent.<\/p>\n

What does RAL installation mean?<\/h2>\n

The term comes from the installation guideline for windows and entrance doors published by the German RAL quality association for windows, fa\u00e7ades and entrance doors (RAL-G\u00fctegemeinschaft Fenster, Fassaden und Haust\u00fcren). It describes how the joint between window and masonry should be planned and carried out in line with recognised good building practice. At its heart is the three-layer principle<\/strong>.<\/p>\n

\"Diagram
The three-layer principle of RAL installation: tighter on the inside than on the outside.<\/figcaption><\/figure>\n

The three layers in detail<\/h2>\n

1. Inside: airtight<\/h3>\n

On the room side, the joint is sealed airtight and vapour-retarding, for example with a special membrane or sealing tape. This prevents warm, moist indoor air from entering the joint and condensing there.<\/p>\n

2. Middle: insulated<\/h3>\n

In the middle, insulation material or expanding foam provides thermal and acoustic insulation. This functional layer must stay permanently dry \u2013 only then does it insulate reliably.<\/p>\n

3. Outside: weathertight<\/h3>\n

On the outside, a tape protects the joint against driving rain and wind. At the same time it is vapour-permeable, so that any moisture that has got in can escape to the outside. The basic rule is therefore: tighter on the inside than on the outside<\/strong>.<\/p>\n

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Windows with professional installation<\/p>\n

We supply and install your windows from a single source \u2013 carefully and on schedule.<\/p>\n

Get advice \u2192<\/a><\/div>\n

Fixing: foam is not a fastener<\/h2>\n

The window must be mechanically anchored in the masonry \u2013 with frame plugs, screws or fixing anchors \u2013 and set on load-bearing blocks that transfer its weight into the structure. Expanding foam only insulates; it does not hold the window in place. Secure fixing is particularly important for heavy units such as lift-and-slide doors<\/a>.<\/p>\n

Special case: installation within the insulation layer<\/h2>\n

On houses with external wall insulation (ETICS), the window can be positioned in front of the masonry, within the insulation layer. Special mounting brackets and consoles are available for this. This type of installation reduces thermal bridges at the reveals, but it requires careful planning.<\/p>\n

How to recognise a good installation<\/h2>\n