The window as a component frame sections

Materials for outer and sash frames Untreated wood

The following measures must be taken to ensure the durability of wooden windows:

Choose suitable, resistant species of wood such as pine, spruce, fir and larch. Ensure that water can drain away from all sections and surfaces.

Ensure protection by providing an appropriate surface treatment: priming is a preventive measure protecting against discolouring mould growth. Impregnation prevents rotting caused by moisture.

Painted wood

Wood can be painted many different colours. Opaque paints have a lower water permeability than mere impregnation and they protect against rot. Problems: resistance to ultraviolet radiation, vapour pressure from inside (in the case of thick coats of paint on the outside of the window).


This is the combination of a loadbearing construction of wood on the inside and an aluminium facing on the outside. The latter protects the wood, but the architectural expression of the window varies from inside to outside.


PVC is the most common material for the production of plastic windows. The material of the frame sections is initially white; it can be dyed or coated, but not painted.

The frame sections are hollow (single- or multi-chamber systems), with various forms readily available. Despite the inclusion of metal stiffeners to strengthen the chambers, plastic windows are known for their relatively low structural strength.

Aluminium and steel

Metal windows have a high thermal conductivity and so the frame sections must include a thermal break.

Aluminium windows: Stability is relatively good and so aluminium is suitable for large elements. As a rule, the surface is treated because otherwise the irregular oxidation of the material leads to blemishes.

We distinguish between mechanical surface treatments, e.g. grinding, brushing and polishing, and the electrochemical anodising process, which produces a consistent oxide layer. Stove-enamelling involves bonding a coat of paint to the metal surface by firing.

Steel windows: Mainly used for industrial buildings. Much more stable than aluminium windows. Large window assemblies, especially together with the glazing, are very heavy (installation problems).

The biggest disadvantage is the risk of corrosion, which can be reduced by painting or galvanising. Like aluminium windows, steel windows can be given a stove-enamelled finish.

Fig. 25: Window sample

Frame: untreated wood; insulating glazing

Fig. 25: Window sample

Frame: untreated wood; insulating glazing


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Project Management Made Easy

Project Management Made Easy

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