What is the Best Material to Put Under Decking?

Henry A

A suitable foundation is crucial when deciding to build a deck. Not only will it provide structural integrity, but it also protects the deck from many forms of damage that can shorten its lifespan. But when choosing what to use for your composite decking foundation and frame, which is the best material?

What to Use for Deck Foundation


Creating a stable foundation is one of your goals when building a deck. However, you will also need to choose one that will prevent damage to your decks, such as moisture, weeds, and moulds. The good news is, you have a few options that you can choose from. Many professional and self-made builders agree that gravel is the perfect material to place under your deck. How can you put gravel as your deck’s base?

First, you will need to prepare the installation area and dig a few inches out. Then, you’ll need to cover the area with landscaping fabric. Finally, spread gravel until you fill the gap to ground level. Gravel provides excellent drainage, along with landscaping fabric. It also acts as a mulch, preventing weed growth, which can be very damaging to decks.

Another advantage of using gravel is that it can provide a backdrop for your landscaping design. Many outdoor designers use it to create aesthetically pleasing borders for their patio. If you don’t have gravel, any non-organic mulch works as an excellent substitute.

Concrete Slabs and Blocks

Another popular option is concrete. It’s stable, hard, and many homeowners already have one in their backyards, making it a perfect foundation for your deck. Even if you don’t have one yet, you can get one installed easily and for cheap. However, if you are using an existing concrete slab, you will need to ensure that it is in good shape. If you have water pooling problems or have noticeable cracks, you may want to mend them first. These problems can sink and ruin the slab, taking the decking boards along with it.

Aside from slabs, you can also install a deck using concrete blocks, especially if you plan to build floating decks. You can use ordinary ones or precast varieties that fit the frame of the deck. The primary use of these blocks is to raise the deck so that they won’t be touching the ground. However, you may still want to de-weed the dirt or cover it with landscaping fabric to add more protection.

What to Use for the Frame

material to put under decking

Aside from the foundation, the frame is another crucial part of the deck. It will hold the decking boards in place, ensuring they are safe, stable, and durable. For the frame of decking, you can use different materials.

One of the cheapest and most recommended materials to use for frames is pressure-treated lumber. Unlike ordinary wooden boards, pressure-treated lumber has better protection against moisture and insect damage.

Another option you can choose is composite lumber. Like composite decking boards, they offer superior durability against water, moisture, moulds, and warping. Despite their higher cost, they will provide better framing for decks, especially if you are also using composite decking boards.

Decking Boards that You Use Matters

The type of decking boards you choose matters when determining what to use as the base material for your deck. How so? What is the best choice when it comes to decking boards?

Many enjoy wooden decking boards for their affordable cost, and they are relatively easy to find. However, they are more prone to water damage, mould and mildew growth, and insect damage. For this reason, you may need to choose better materials for the base to protect your wood decking from these types of issues.

On the other hand, other materials, such as composite decking, are more resistant to problems you may encounter with wood. While that doesn’t mean that you will disregard any precautions when choosing the base materials, you can be sure that it will last longer as long as it has a proper foundation and frame, regardless of what kind.

To summarize everything, you can use gravel or concrete as an excellent base for your deck’s foundation. When building a frame, you will need to use at least pressure-treated wood. Using higher-quality materials, like composite decking, will ensure that you will have a stable, durable, safe, and long-lasting deck with proper foundation and frame.

Tags: decking foundation

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