Clear Vegetation and Level the Deck Area
Before you dig post holes, you need a clean work area. Clearing grass, weeds, rocks, and debris makes digging easier and prevents organic matter from decomposing under your deck. A properly prepped ground surface also improves drainage and reduces pest problems for the life of your deck.
Quick Summary
Time needed
2-6 hours
Cost
$50-200
Difficulty
Labor intensive
Why Proper Site Clearing Matters
The space under your deck is out of sight, but it shouldn't be out of mind. What you do (or don't do) now affects your deck for years to come.
Skip This Step
- • Weeds grow through deck boards
- • Decomposing matter attracts pests
- • Moisture and mold problems
- • Musty odors from underneath
- • Harder to fix later
Do It Right
- • Weed-free for years
- • Better drainage
- • Fewer pest problems
- • Cleaner appearance
- • Easier maintenance
The hour or two you spend now prevents ongoing maintenance headaches and keeps your deck looking great from every angle.
What You'll Need
Materials
- •Landscape fabric — Heavy-duty, not cheap weed cloth
- •Landscape staples — 6-inch steel staples
- •Gravel (optional) — 2-4 inches of pea gravel or river rock
- •Trash bags — For debris removal
Tools
- •Flat shovel — For cutting sod
- •Rake — For leveling and debris collection
- •Wheelbarrow — For hauling removed material
- •Sod cutter (optional) — Rental for large areas
Pro tip: For decks over 200 sq ft, renting a sod cutter ($50-75/day) saves hours of work compared to manual removal. It cuts sod into neat strips that roll up easily.
Step-by-Step Site Clearing Process
1. Remove Grass and Sod
Start by removing all grass from the deck footprint area, plus about 6 inches beyond the edges.
Manual Method
- • Use a flat shovel to cut sod into manageable sections
- • Cut 12-18 inch strips, then slice into squares
- • Slide shovel under roots to lift sod
- • Stack sod for composting or disposal
Sod Cutter Method
- • Adjust blade depth to cut just below roots (2-3 inches)
- • Make parallel passes across the area
- • Roll up cut strips like carpet
- • Much faster for large areas
2. Clear Rocks, Roots, and Debris
After removing sod, go through the exposed soil and remove anything that could cause problems later:
- •Large rocks that could interfere with footings
- •Tree roots (cut cleanly with loppers or saw)
- •Old construction debris, concrete chunks
- •Buried landscape timbers or edging
Watch for: Old sprinkler lines, low-voltage wiring for landscape lighting, and pet fence wires. These are often buried just a few inches down.
3. Remove Organic Topsoil
The rich, dark topsoil is full of organic matter that will decompose over time. Removing it prevents settling and reduces pest attraction.
- •Scrape away the top 1-2 inches of soil after sod removal
- •Remove any remaining plant matter, mulch, or leaves
- •Get down to harder, mineral soil
Reuse the soil: Topsoil and sod can be composted or used elsewhere in your yard. Consider creating a small berm or improving a garden bed.
4. Grade for Drainage
Water should flow away from your house, not pool under the deck. Check the slope and adjust if needed:
Minimum slope: 1/4 inch per foot away from house
A 12-foot deck should drop at least 3 inches from house to outer edge
- •Use a long level or laser level to check slope
- •Add or remove soil to create proper drainage
- •Fill any low spots that could collect water
5. Install Landscape Fabric
Cover the entire area with heavy-duty landscape fabric to prevent weed growth. This is your long-term defense.
- •Roll out fabric to cover the entire cleared area
- •Overlap seams by at least 6 inches
- •Secure with landscape staples every 2-3 feet
- •Cut X-shaped holes for post locations (don't cut until ready to dig)
Important: Use commercial-grade landscape fabric, not thin weed barrier. Cheap fabric degrades in 1-2 years and weeds push right through it.
6. Add Gravel (Optional but Recommended)
Adding 2-4 inches of gravel over the landscape fabric provides extra benefits:
- •Improves drainage and prevents puddling
- •Holds fabric in place permanently
- •Deters rodents and insects
- •Looks clean if visible from the sides
Pea gravel and river rock are popular choices because they're attractive and allow good water flow. Calculate about 1 cubic yard of gravel per 100 sq ft at 3 inches deep.
Common Mistakes to Avoid
Using plastic sheeting instead of landscape fabric
Solid plastic traps moisture and creates a humid environment that promotes mold, rot, and insect problems. Always use permeable landscape fabric that allows water to pass through.
Not overlapping fabric seams enough
Weeds are persistent. They'll find every gap. Overlap seams by at least 6 inches, and consider 12 inches for aggressive weed areas. Secure all overlaps with staples.
Creating a bowl that collects water
If you remove too much soil near the center or not enough near the edges, water will pool under your deck. Always slope away from the house and maintain positive drainage.
Leaving large tree roots
Tree roots continue to grow and can push up footings or crack concrete. Cut any significant roots cleanly. For roots over 2 inches diameter, consult an arborist about tree health.
Frequently Asked Questions
Do I need to remove grass under a deck?
Yes. Grass and weeds can grow in low-light conditions and push through deck boards. Decomposing organic matter attracts insects and creates odors. Removing vegetation now prevents these problems.
What is the best ground cover under a deck?
Landscape fabric covered with 2-4 inches of gravel is ideal. The fabric blocks weeds while allowing drainage. Gravel improves drainage further and deters pests. Pea gravel or river rock looks attractive if visible.
Should I put plastic under my deck?
No. Solid plastic traps moisture and creates conditions for mold, rot, and pests. Use permeable landscape fabric instead, which blocks weeds but allows water to drain through.
How do I prevent weeds under my deck?
Remove all vegetation and scrape away topsoil containing seeds. Install heavy-duty landscape fabric with 6-inch overlapping seams. Add 2-4 inches of gravel on top. This combination prevents weeds for many years.
Ready for the Next Step?
With the site cleared and prepped, you're ready to start digging post holes at the marked locations.