Decking Supports for Uneven Ground

August 7^th, 2024 in Civils

When installing decking on uneven ground, it’s essential to create a stable and level base to ensure the longevity and safety of the structure. Here are some common methods and supports used for decking on uneven ground:

Concrete Footings

Poured concrete bases that provide a solid and stable foundation for deck posts, concrete footings provide a solid and stable base for decking.

Pros:

High Stability: Excellent support and stability for large or heavy decks.
Durability: Long-lasting and resistant to shifting or settling.
Code Compliance: Often required by building codes for elevated or attached decks.

Cons:

Labour-Intensive: Requires significant time and effort for digging, pouring, and curing.
Cost: More expensive due to materials and labor.
Weather Dependency: Needs good weather conditions for installation.

Best For: Large, permanent decks, especially those attached to a house.

Installation Process

Here’s a basic outline of the installation process:

Mark the Deck Area: Outline the area where the deck will be installed.
Dig Holes for Footings: Dig holes at regular intervals to the frost line depth.
Pour Concrete: Pour concrete into the holes to create footings.
Install Post Anchors: Place post anchors into the wet concrete to hold the deck posts.

Adjustable Deck Supports (Deck Risers or Pedestals)

Adjustable deck supports, also known as deck risers or pedestals, allow for precise levelling of the deck surface:

Pros:

Easy Levelling: Simple height adjustments to accommodate uneven ground.
Flexibility: Can be used on various types of terrain.
Quick Installation: Faster and easier to install compared to concrete footings.

Cons:

Load Limitations: May not support as much weight as concrete footings.
Cost: Can be expensive, especially for high-quality adjustable supports.
Material Durability: Often made of plastic, which may not be as durable as other materials like metal or concrete, potentially degrading over time due to weather exposure.

Best For: Medium-sized decks where quick installation and adjustability are important.

Installation Process

Here’s a basic outline of the installation process:

Position the Supports: Place adjustable supports at regular intervals under the decking framework.
Adjust Height: Twist or screw the supports to raise or lower the decking to the desired level.

Post and Beam Construction

This traditional method involves creating a framework of posts and beams to support the decking.

Pros

Strong Support: Provides excellent support for large decks.
Versatility: Suitable for a variety of deck designs and terrains.
Durability: Long-lasting and stable foundation.

Cons

Complex Installation: Requires precise measurements and alignment.
Labour-Intensive: Significant effort needed for digging and setting posts.

Best For: Large, permanent decks, particularly on uneven terrain.

Installation Process

Install Posts: Set posts in concrete footings at regular intervals.
Attach Beams: Secure horizontal beams to the posts to create a level framework for the decking.

Ground Screws

Ground screws are a modern and efficient alternative to concrete footings, especially useful for uneven terrain.

Pros

Minimal Excavation: No need for extensive digging.
Quick Installation: Fast to install with the right equipment.
Environmentally Friendly: Less disturbance to the ground compared to digging.

Cons

Special Tools Required: May require special machinery or professional installation.
Soil Compatibility: Not suitable for all soil types, especially very rocky or extremely soft soils.

Best For: Projects requiring minimal ground disturbance and quick installation.

Installation Process

Screw into the Ground: Use a machine or hand tool to screw the ground screws into the earth at regular intervals.
Attach Deck Framework: Secure the decking framework to the tops of the ground screws.

Concrete Blocks

Precast concrete blocks can be used as a simple and quick solution for supporting decking.

Pros

Ease of Use: Simple and quick to install with no curing time needed.
Cost-Effective: Generally less expensive than poured concrete footings.
Mobility: Easy to move and reposition if needed.

Cons

Stability: Less stable and secure than poured footings, especially on soft ground.
Shifting: Can shift or settle over time, requiring adjustments.

Best For: Small to medium-sized, freestanding decks on relatively level ground.

Installation Process

Place Blocks: Lay concrete blocks on the ground in a grid pattern to support the deck framework.
Adjust for Level: Use shims or other materials to adjust the height of the blocks and level the decking.

Floating Deck

A floating deck is not attached to the house and “floats” on the ground.

Pros

Flexibility: Can be moved or reconfigured easily.
Easy Installation: Less complicated to install compared to fixed decks.
Cost-Effective: Generally cheaper due to simpler design and materials.

Cons

Limited Height: Typically built low to the ground.
Potential Movement: More likely to shift or settle over time.

Best For: Small, temporary, or movable decks on relatively flat ground.

Installation Process

Prepare the Ground: Level the ground as much as possible.
Use Pavers or Concrete Blocks: Place pavers or concrete blocks directly on the ground to support the deck.
Build Frame on Supports: Construct the decking frame on top of the pavers or blocks.

Summary

Concrete Footings: Best for stability and durability; ideal for large, permanent decks but requires more effort and cost.
Adjustable Deck Supports: Great for easy levelling and quick installation; suitable for medium-sized decks.
Ground Screws: Quick and minimal disturbance; ideal for projects needing fast setup but not suitable for all soil types.
Concrete Blocks: Easy and cost-effective; good for small, freestanding decks.
Post and Beam Construction: Strong and versatile; suitable for large decks but labour-intensive.
Floating Deck: Flexible and easy to install; best for small, low-to-ground decks.

Tips for Success

Site Preparation: Clear and prepare the site by removing vegetation and debris. A layer of landscape fabric can help prevent weed growth.
Drainage Considerations: Ensure proper drainage by sloping the ground slightly away from structures.
Building Codes: Check local building codes and regulations for deck construction to ensure compliance.
Safety: Wear appropriate safety gear and consider hiring a professional if you’re unsure about any part of the process.

Each of these methods can be adapted to suit the specific requirements of your site and the design of your deck.