When should you avoid pouring a concrete foundation?

Pouring a concrete foundation on a frozen sub-grade is inappropriate because the presence of frost can severely affect the curing process of the concrete. When concrete is placed on frozen ground, it can lead to several issues, such as improper setting and a compromised bond between the concrete and the sub-grade. Additionally, the freezing temperatures can cause moisture within the mix to freeze, leading to cracks, reduced strength, and integrity problems in the final product.

In contrast, while pouring concrete during windy conditions, extreme heat, or heavy rain can pose challenges and require specific precautions, it is primarily the condition of the sub-grade freezing that directly interferes with the fundamental properties of concrete. Therefore, avoiding pouring on frozen ground is paramount to ensure the quality and durability of the foundation.