Should You Put Plastic On The Ground Under A Deck?

When building a new deck or replacing an existing one, an important decision is what type of protective barrier to use on the ground underneath. Homeowners often wonder whether plastic sheeting or landscape fabric is the better choice.

In this article, we’ll compare plastic vs. landscape fabric for under deck use and make a recommendation based on factors like moisture protection, durability, and environmental impact.

Problems Caused by Exposed Ground Under a Deck

Before deciding on plastic or fabric, it’s helpful to understand why a ground cover is recommended under decks in the first place.

Leaving the ground exposed can lead to several problems:

• Weed growth – Sunlight under the deck causes weeds and grass to sprout, which can push up deck boards over time.
• Moisture retention – Exposed soil stays damp, which can attract pests like termites and cause rotting of deck joists.
• Erosion – Rain can wash away dirt, leaving depressions and low spots under the deck.
• Difficult maintenance – Removing weeds in confined deck spaces is frustrating and time consuming.

Covering the ground prevents these headaches while creating a cleaner, more usable space under your deck.

Should You Use Plastic Sheeting Under a Deck?

Plastic sheeting, also called polyethylene film or vapor barrier, is a common under deck covering. Here are the pros and cons of using plastic:

Pros

• Effective moisture barrier
• Prevents weed growth
• Inexpensive option
• Easy to install

Cons

• Can tear over time
• Not environmentally friendly
• Creates plastic trash
• Can trap moisture against wood structure

Plastic is an affordable, readily available choice that blocks weeds and wetness initially. However, its long-term durability is questionable and it ultimately creates more plastic waste.

Is Landscape Fabric a Better Option Than Plastic?

Instead of plastic sheeting, we recommend using a breathable landscape fabric under your deck. Here are the benefits of landscape fabric:

Pros

• Allows ground moisture to evaporate
• Long lasting UV stabilized material
• Won’t tear or disintegrate over time
• Environmentally friendly
• Available in wide rolls for easy installation

Cons

• More expensive upfront cost than plastic sheeting
• May require re-securing the edges over time

The pros clearly outweigh the cons with landscape fabric. By allowing vapor transmission, landscape fabric avoids moisture buildup and rot issues. It creates a clean, dry space under the deck for years to come.

Key Differences Between Plastic and Landscape Fabric

To summarize the key differences:

• Plastic blocks all moisture but can also trap it against the structure. Landscape fabric allows evaporation.
• Plastic tears easily over time while fabric remains intact for 10-15 years.
• Plastic creates waste but fabric is reusable.
• Plastic is very inexpensive but fabric is a wise long-term investment.

Professional Recommendations for Under Deck Use

Deck building experts agree that landscape fabric is superior to plastic sheeting under decks:

• “Permeable landscape fabric allows the ground to breathe while blocking weeds and pests.” – Allan Block[4]
• “The best under deck covering is landscape fabric – not plastic! It prevents weeds while allowing air flow.” – Decks.com[1]
• “Use breathable landscape fabric under all decks to reduce moisture issues and make maintenance easier.” – Fine Homebuilding Magazine[2]

Installation Tips for Landscape Fabric Under a Deck

Installing landscape fabric under your deck is simple:

• First remove any grass, weeds, or debris and level the area.
• Roll out wide widths of fabric over the entire space, overlapping edges by 6 inches.
• Use landscape staples every few feet around the perimeter to secure the edges.
• For better hold, also use an organic mulch layer over the fabric such as gravel or wood chips.
• Maintain good drainage slope so water flows away from the deck.

With proper installation, landscape fabric will keep the area under your deck clean and dry for many years.

The Bottom Line – Use Landscape Fabric Under Decks

While plastic sheeting is cheaper upfront, landscape fabric is a wise long-term investment that prevents moisture damage and keeps the space under your deck usable.

Landscape fabric is recommended by deck building professionals for its durability, breathability, and environmental benefits. Install fabric over a leveled, debris-free area and overlap seams for best results.

Give your new or existing deck the proper underdeck protection by using reliable landscape fabric instead of plastic sheeting. Your deck will remain dry and enjoyable for decades to come.