What is a deck block?

A deck block, also known as a concrete deck block or foundation block, is a precast concrete block designed to provide a stable base for various structures, primarily decks, porches, and small outbuildings like sheds. These blocks are typically square or rectangular in shape and have one or more channels or depressions on the top surface to accommodate the beams or joists of the structure they support.

Deck blocks are a popular alternative to traditional concrete footings or poured concrete foundations, especially for smaller, less complex projects. They are relatively easy to install and are useful when you want to avoid digging deep holes and pouring concrete. They are often used for decks in areas with frost-free climates or when the deck is relatively low to the ground.

Here’s how deck blocks are typically used:

Placement:
The deck blocks are placed directly on the ground, typically on a compacted gravel or sand base to ensure stability and drainage. They should be spaced according to your deck design and local building codes.

Beams and Joists:
Wooden beams or joists are then placed on top of the deck blocks, fitting into the channels or depressions on the block’s surface.

Decking Material:
The decking material, such as wood boards or Cellular PVC decking, is installed on top of the beams and joists to create the deck’s surface.

A warning…

It’s important to note that deck blocks are not suitable for all situations. Canada’s climate makes them problematic here. In areas with frost heave or heavy loads, traditional concrete footings or screw piles are much a better choice. A building professional should always be consulted to ensure the viability of any project where safety is an issue.