Creating Modular Decking

These simple structures, often called duckboards, are easy to build, and they can be combined into a myriad of shapes with an attractive parquet design. If you have a level yard and soil that is not soggy, they can last a long time. If you lay them on a firmly tamped bed of gravel, they will remain fairly stable. If you are going to use modular decking in high-traffic areas or find the modules have more spring to the step than you’d prefer, add a 2x4 cleat to the center of each module as reinforcement.

Tools: Basic carpentry tools.

Combine basic modules. A modular deck can be constructed in a weekend and installed on any level surface in your yard. It requires no connection to the house and no foundation. Add or subtract modules to suit your needs.

Mix and match modules. With a bit of creativity, you may be able to think of several ways to combine modular construction with standard deck-building techniques. For example, here the modules form a path from the garage to the deck. If your needs or traffic patterns change over the years, it is a simple matter to pick up and rearrange the modules. You can even stack them to make low steps. Alternate the direction of the decking for a parquet effect, as shown, or lay them so the decking lines are continuous.

Add units to form any pattern. Modular construction, by its nature, is versatile and adaptable. You can use the modular approach, for example, to build a large border around a flower bed. A larger deck could encompass several individual beds. The modular approach works particularly well for raised gardening beds. For noninvasive plants, simply arrange the modules around an open space. For larger plants or for a raised bed, build a simple planter box and butt the modules up to it.

1. Prepare the site. Use batter boards and mason’s lines to mark the outline of the area. Allow for a 3-inch border of sand around the perimeter of the deck. Use the 3-4-5 method to ensure a square layout. Remove the sod and soil to a depth of 5 inches (or more or less, depending on how high you want the deck to sit). Spread 3 inches of gravel on the ground, level and tamp it, then add 1 1/2 inches of sand. Level and tamp again. For an extra-firm surface, rent a vibrating tamper.

Save the Sod - The sod and topsoil you remove to make room for your deck can be added to your compost pile. Be sure to place the grass side down to stop the grass from growing. Before you do so, however, think about some other uses you may have for it. Perhaps part of your yard would benefit from transplanted sod—an out-of-use garden bed might need just such a boost. Use a straight-bladed shovel and cut the sod in careful rectangles to pull up sections of sod that can be laid out easily in another location. Be sure to pull up as many of the roots as possible as you work.

2. Gang cut the boards. For each module, you need ten 29-inch pieces of pressure-treated 2x4s. Make the job go faster by setting several 2x4s edge to edge on sawhorses, then cutting them in one pass with a circular saw. Use a straightedge to clamp the boards and guide the saw.

3. Build a jig. To ensure each module is identical and perfectly square, make this jig out of 2x4s. Use four boards, each about 3 to 4 feet long. Make sure the inside edges are straight and measure 29x29 inches. Align the corners with a framing square before nailing the boards together. Use several nails at each corner. The jig doesn’t have cross bracing, so be sure to check it for square from time to time.

4. Build the modules. Set the jig on a solid, flat surface, such as a concrete driveway. Each module requires eight decking pieces and two bottom cleats. Set two boards on end at opposite sides of the jig, as shown, to act as nailing cleats. Attach the rest of the boards with 12d galvanized nails or 2 1/2 -inch decking screws. Space the boards with the 12d nails, making a 1/8-inch gap between boards. You may need to adjust the spacing to make the last piece come out even with the end of the cleats.

5. Set the modules. Lay the modules in place, alternating the direction of the boards if you want a parquet effect. Attach the modules to each other by drilling pilot holes and driving in galvanized nails or decking screws at an angle.

6. Add the edging. Once you have assembled the modules in a pattern, you may want to install 2x4s around the edges of the deck to add a finishing touch. Cut two 2x4s to fit flush with the decking and install them on opposite ends. Remove enough sand to allow the edging to rest flush with the deck surface. Then cut two more 2x4s long enough to overlap the ends of the installed edging. Replace the sand and tamp around the edges.

Wood Path - These simple modules can serve another function. Set them end to end to form a wood path or sidewalk. The modules are considerably easier to build and install than a concrete walkway or a brick sidewalk. Use the wood path to connect the house to the garage, or the house to a freestanding deck. Use the jig shown in steps 3 and 4 to build 29-inch-wide units, or adjust the size of the jig for a narrower version. With a bit of excavation, the modules could be set to rest at grade. In areas with cold climates, it may make sense to store the modules in the garage during the winter.

Safe Heights

■ The maximum acceptable length of posts that you can use on a given deck depends on several factors, including the size of the post, wood species and quality, the sizes and spans of joists and beams, and local building codes and regulations.

■ Higher decks require larger posts spaced closer together and resting on larger foundations.

■ If the posts on your deck also will support a substantial overhead structure, check with a professional or your local building department officials about the best size to use.

Locate the footings. It’s crucial to locate footings correctly so the posts they support will be exactly plumb as they reach far upward to support an elevated deck. Begin by accurately locating a reference point for the entire framing structure. The easiest way is to install the ledger board, then hang a plumb bob from the corner. This identifies the location of the corner of the framing, so make the correct calculations to figure the true reference point for the footings.

To lay out the actual location of the first footing, use the 3-4-5 method to extend a mason’s line out from the house at exactly 90 degrees. If your property slopes, have a helper hold a board with a level on it, with its end resting on the ground where the footing will be. When the outward measurement is correct and the board is plumb in both directions, you will have the correct location.

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