How To Extend a Patio

Expanding an existing patio can transform your outdoor living space, creating more room for entertaining and relaxation without the need for a complete overhaul. In this guide, we’ll walk through the process of extending a patio. This Old House mason Mark McCullough demonstrates the steps to create a modern and functional patio extension in the video above.

Planning Your Patio Extension

Before breaking ground, take the time to carefully plan and prepare for your project.

Design and Layout

Start by sketching your desired patio extension on grid paper. This step will help you visualize the final result and make necessary adjustments before starting the physical work. Measure the existing patio, then consider the shape, size, and overall aesthetic of the extension. Think about how you’ll use the space—for dining, lounging, or both—and design accordingly.

Pro Tip: Landscape architect Paul Maue advises: “Make sure the patio is big enough. Getting the scale right is the hardest thing—you always need more space than you think.” Try setting up a table and chairs on the lawn first to see how much room they need. Maue’s rule of thumb: Allow 25 square feet per person for a seat and room to move.

Material Selection

Choose materials that complement your existing patio while adding a modern touch. Consider the color, texture, and compatibility with your existing patio materials, as well as durability, maintenance requirements, and cost. Selecting the right patio pavers will ensure a cohesive and appealing extension that blends seamlessly with your current setup.

In the video, Mark opts for granite pavers in various sizes, offering durability and a contemporary look. Here’s what you need to recreate his design:

• Marking paint
• Crusher run, or crushed stone
• Conduit or pipe
• Stone dust
• 2x4s
• Patio pavers of varying sizes
• Strips of synthetic grass
• Landscaping spikes

Tools

Make sure you have the right tools for the job. If you have a lot of earth to move, we recommend renting an excavator from Home Depot. Here’s what else you need:

Permits and Regulations

Check with your local building department about permits. Some areas have regulations regarding the size of outdoor living spaces or their proximity to property lines. Compliance with local codes will prevent any legal issues down the line.

Pro Tip: In a This Old House project visit, a local building inspector named Fred explained the value of working with your building department rather than avoiding it: “We’re really here to help the homeowner and protect the homeowner to make sure the contractor is doing what they’re supposed to be doing. That’s why they bring in the plans. We look at those, we do a plan review. Then we come out and actually see if they do what they say they’re going to do on the plans.”

Preparing the Site

The patio must slope away from the house or other structure to direct runoff away from the foundation. Grade the slope about ⅛ inch per foot. To keep track, run a mason’s line at the proper slope and measure down from it as you dig. Set stakes at the high and low corners, run a level mason’s line between them, then lower the line on the low-side stake by ⅛ inch for every foot of length.

Site preparation ensures a stable, level foundation that prevents the patio from settling and cracking over time. Here are the key steps involved:

1. Mark the area: Use marking paint to outline your new patio area. Make sure the outline is square and level with the existing patio.
2. Identify underground utilities: Before digging, contact your local utility locator service, or dial 811 to reach the national “Call Before You Dig” hotline. Your local utility companies will send someone to mark any underground lines.
3. Excavate: Use an excavator or shovel to remove all topsoil within the marked area. Dig deep enough to accommodate a 6-inch base layer plus the thickness of your pavers. Clean up the corners and edges with a shovel so they’re square.
4. Create a solid base: Pour crusher run (crushed stone) into the excavated area. Spread the crusher run evenly with a metal rake to a thickness of about 6 inches.
5. Compact the base: Use a plate compactor or hand tamp to pack down the base layer. Check for level and adjust as needed.

Installing the Pavers

With a solid base in place, you’re ready to lay the pavers for your patio extension. Follow these steps:

1. Pour the stone dust: Lay two 1-inch diameter pipes on top of the crusher run to represent the thickness of the stone dust layer. Pour stone dust into the excavated area and spread it around with a rake, being careful not to disturb the pipes.
2. Level the stone dust: Lay a 2×4 board across the pipes and shimmy it back and forth to level the stone dust. Fill in any low areas as needed.
3. Place the pavers: Starting in a corner, follow the plan you created on grid paper to lay out the patio pavers. In the video above, McCullough and the homeowner use small pieces of 2x4s to create even 4-inch gaps between the stones.
4. Set and level the pavers: Tap the pavers into place and ensure they’re level. Cut pavers as needed to fit around obstacles or edges.
5. Fill the gaps: Cut strips of synthetic grass to fit the gaps between pavers. Place the grass strips in the gaps, ensuring they’re even with the paver surface. Secure the grass strips with landscaping spikes if needed.

Pro Tip: Roger, a This Old House landscape contractor, explains the difference between stone dust and crusher run: “Stone dust is different than crusher run ’cause it has no big stones in it. So when we lay it out and compact it, we’re gonna have a perfectly flat bed to lay the brick on.” Standing the screed up and running it down the rails leaves the perfect height for setting pavers.

During a This Old House project, the crew noted that synthetic grass technology has come a long way, and it’s now a popular choice for filling paver gaps. As one expert on the project explained, it’s become so prevalent in patios like this that manufacturers actually make synthetic grass in four-inch strips designed specifically for the gaps between pavers. Compared to natural dirt and seed, synthetic grass is low maintenance and resistant to weeds—making it a practical, no-fuss option.

Finishing Touches

Give your patio extension a neat, finished look with these final steps:

1. Install edging: Choose edging material that complements your pavers, then install it around the perimeter of your new patio to keep everything in place. Make sure the edging is secure and level with the paver surface.
2. Ensure proper drainage: Make sure the patio slopes slightly away from your house (about 1/4 inch per foot) to prevent water from pooling. Consider installing a French drain if your yard doesn’t naturally drain well.
3. Enhance with landscaping: Add plants or shrubs to soften the edges of the patio. Consider installing landscape lighting so that you can use your patio during the evening hours.
4. Set up the space: Place outdoor furniture and decor to complete the look and functionality of your expanded outdoor living space.