General conditions of building works in winter periods are given in ITB Instruction, No. 282: Execution of building structures in lowered temperatures. Building in winter conditions (in temperatures below +5°C) using H+H aerated autoclaved concrete blocks is possible after fulfilling several requirements which should be absolutely observed during the works.

• A decision on the commencement of building works can be made by the site manager or supervision inspector who takes a full responsibility for the issued decision concerning the commencement of building works.
• H+H aerated autoclaved concrete blocks used in building cannot be covered by snow or frost, they cannot be frozen as well. It means that the block cannot be stored in the temperature lower than –2°C for a period longer than 24 hours and therefore it is recommended to store them in original packages in rooms of temperature above zero.
• While building in winter conditions we recommend to use a special H+H mortar designed for the works in winter conditions. It allows to build in conditions of light winter in temperatures dropping periodically to –5°C. A detailed use scope of winter mortar is given in product technical data placed on the bags.
• Before the commencement of building it is necessary to control if a wall executed last day is bound correctly. The control is carried out through horizontal powerful hitting a block of top wall surface by means of a rubber hammer. If hitting does not cause disconnection of the block, building can be continued.

Building works cannot be carried out:

• in temperatures below –5°C; the works can be commenced only when the temperature of wall environment is higher than +2°C for at least 48 hours,
• on a frozen wall; a wall is regarded as a frozen one after 48 hour stay in the temperature which is lower than –2°C,
• during atmospheric precipitation when a freshly executed wall should be protected by means of a cover protecting against its too fast cooling down.

A wall executed in winter conditions can be loaded by ground pressure or strong wind activity after about one week appearance of  temperatures above zero; by this time the wall should be protected against the activity of these horizontal loads.
Complying with the afore-mentioned recommendations and complying with the ITB Instruction, No. 282: Execution of building structures in lowered temperatures causes that the executed wall works are executed correctly.