Site Conditions to Consider when Welding a Flat Roof

​Substrate Properties
A properly prepared substrate should be solid, evenly laid, and free from debris such as loose screws or stones.

Rain
If it is raining, welding must not be carried out without special protective equipment.

Air Temperature
Welding must be suspended at temperatures below +5°C in order to prevent the material from being exposed to an excessively high thermal load (in accordance with DVS 2225-4).

Humidity
In some cases, excessively high humidity can cause condensation to form on the welding surface, which has a negative effect on seam strength.

Wind
If there is strong wind, the tool may not reach the required welding temperature. This can be counteracted by raising the welding temperature by 20 to 30°C or reducing the speed by 20 to 40 cm/min. If the wind is excessively strong, the welding area should be shielded against wind or welding should be suspended.

Sun
Prolonged exposure to the sun can cause the material to heat up significantly causing thermal expansion. This causes wrinkles which makes the welding process more difficult and leads to an unacceptably high level of tension in the seam area when the material cools.

Maintaining the Tools
The air inlet and filter should be cleaned frequently and the heating element removed and cleaned periodically. This ensures the tool is able to produce the correct air volume and temperature output.

Using Generator Power
The generator must have the correct specifications in order to ensure safe operation:

• VARIMAT V2: Min. 10 KW to ensure a reserve for hand tools
• UNIROOF AT/ST: Min. 6 KW