Glossary – our knowledge from A to Z

That part of a crane that projects beyond its supports.

This describes the rate of airflow via the joint between opening light and window frame. It is expressed by the joint permeability coefficient a², which describes how many cubic metres of air pass through one linear metre of joint in one hour for a pressure difference of 10 Pa.

The joint permeability coefficient (a-value) specifies how much air (in m³) per metre length of joint passes through a window per hour with a pressure difference of 1 kp/m². The smaller the a-value, the tighter the window closes, the lower the heat losses and the better the sound insulation.

The size of the joint between window frame and adjacent building component must be such that all components meeting at this point can expand, contract and move without hindrance. At the same time, the joint must still remain weathertight and watertight.

Sealing materials (e.g. silicone) or sealing products (e.g. tapes, waterstops, precompressed foam profiles) are fitted into joints to prevent the ingress of water.

A sample of material for determining the hardenability in the end quench test according to W. E. Jominy (DIN 50191). The specimen is 100 mm long and 25 mm in diameter.