Gravel Under a Deck

Preparing the Ground Under Your Deck

The space beneath a raised deck can become a haven for weeds and moisture problems if left as bare soil. Covering this area with gravel creates a clean, low-maintenance surface that suppresses weed growth, improves drainage, and prevents animals from making homes under your outdoor living space. A typical deck area of 5 metres by 4 metres needs approximately 1.5 cubic metres of crusher dust or gravel at 75mm depth to achieve these benefits.

One and a half cubic metres of crusher dust weighs approximately 2.4 tonnes. This is a standard bulk delivery that most landscape suppliers handle routinely. The weight makes it impractical to carry by hand, so factor in the labour of wheelbarrowing the material under your deck, particularly if access is restricted.

Why Crusher Dust Works Well

Crusher dust is often the preferred choice for under-deck applications because it compacts firmly into a stable surface. Unlike rounded pebbles that can shift underfoot, crusher dust locks together to form a solid base. This makes maintenance easier if you need to access plumbing or electrical under the deck. The fine particles also provide excellent weed suppression without requiring landscape fabric, though adding fabric beneath the crusher dust provides extra insurance against persistent weeds.

Installation Before or After the Deck

The ideal time to install gravel under a deck is before the deck structure goes up, when you have full access to the area. However, it's still achievable after the deck is built if clearance allows. For low decks with limited access, consider spreading the gravel in sections as you go, working from the furthest point back toward open areas. A leaf rake with a long handle can help spread and level material in tight spaces.

Have a differently sized deck? Use our main gravel calculator to enter your exact dimensions.