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How to Build a Deck

Recommended tools:

—Brushes, rollers (for finish)
—Carpenter's level
—Carpenter's square
—Caulking gun
—Chalk line
—Circular saw
—Claw hammer
—Combination square
—Crescent wrench
—Drills and bits
—Dust mask
—Extension cord
—Framing square
—Hand saw
—Hoe and hose (to mix concrete)
—Nail set
—Plumb bob
—Post hole digger
—Rafter square
—Safety glasses
—Shims or spacers
—Socket wrench
—Stakes or batter boards
—Tape measure
—Tool belt
—Two foot level

Decks originally became popular as a way of adding outdoor living space on hillside lots. Today, many decks are built on level ground where they offer firm, dry footing close to the home. Decks add to the living area of your home and increase its value. Recent studies have shown that in most cases over 200% of the investment can be recouped on decks built by do-it-yourselfers when they sell their house. Decks can be built just inches from the ground or well elevated. They may be freestanding or attached to the home or other building. Before you begin actual deck construction you need to take into account some basic considerations.

Building Code and Zoning Requirements

Many areas require building permits, and your plan may need to be reviewed by your local building code office to make sure that it meets the standards set forth in local codes. Make sure you will be building with any setbacks specified in local regulations. Some communities have rigorous design guidelines and require review committee approval of alterations to the exterior of properties. Contact your local utilities to be sure that your proposed deck won't interfere with access to utility lines. Finally, don't interfere with the functioning or servicing of your septic tank if you have one.

Deck Function

How you plan to use your deck will determine the size deck you need. For family meals and entertaining, select a large deck (or combination of decks) with plenty of space for tables and benches, and consider adding built-in benches along the railings to seat more people. An entry deck can be small, but make it large enough for you to be able to stand and talk comfortably with guests as they arrive or leave.

Your Climate

Sun and wind are the important things to consider. Depending on where you live, afternoon sun can be a welcome friend or a hot, fierce enemy, so plan carefully. Think also about which areas of your yard have pleasant, gentle breezes, or those that always seem too cold or windy. Whatever your local conditions, plan your deck to give you the sun or shade you want with protection from high winds.

Every situation is unique, but the following considerations are common.

Take advantage of good views, both on and off your property and screen off unpleasant ones. Think about how your intended deck use and intended deck placement can work together. An outdoor eating-and-entertaining deck should be close to or easily reached from your kitchen and living area. A deck intended for adult privacy might be better placed away from busy household activities.

Considered together, all these factors may point to an excellent location for you to build your deck, but usually you will have to think about compromises and modifications. For instance, if all other things are perfect about the location for your deck, but you think you'll want more shade, consider adding an overhead arbor or a lattice screen. Is the only problem inadequate protection from high winds? Then add a taller, solid railing along one or two sides. Or does an otherwise great location feel too shady and damp? Perhaps thinning some overhead tree limbs (or even removing a tree) can get more sunlight on your deck.

Basic Rectangular Deck Framing

When most people think of decks, the one that comes to mind is rectangular, elevated on posts, with railing and stairs. The basic framing plan shown for a rectangular deck has some dimensions that are fixed (such as the spacing between joists and the amount of overhang for the ends of joists where they extend past the beams), and others that are described simply as "maximum" (overall length and width of deck, beam and joist spans, height of deck posts, etc.) (See Figure 1).

Step 1: Install Ledger

Install a ledger to anchor the deck to the house and to serve as a reference for laying out footings (Figures 2 and 3). The placement of the ledger determines the level of the deck floor. It is important that it is positioned at the correct height and is horizontal. If you are unsure of how to do this crucial step, consulting a professional contractor is recommended, or design your deck to be free-standing. This will eliminate the need for a ledger board.

Use batterboards and mason's strings to mark off the deck area and locate footings. The strings will help you visualize the size and appearance of the finished deck. (Figure 3)

Square with string

Attach the string to the ledger and/or batterboards making sure it is level. The batterboards should be assembled just outside of the perimeter corners of the deck as illustrated below. Batterboards will be used to hold and adjust strings which define the deck area and height. Use a felt tip marker to mark the string 3' from the corner and mark 4' from the corner in the other direction. Adjust the string until the diagonal connecting these two points is 5'. This will result in a 90-degree angle in the corner. This is commonly referred to as the 3-4-5 method. (Figure 4)

Step 2: Prepare the Site

Decks usually shade the soil sufficiently to prevent most weed growth, but getting weeds out of the way before you begin to build makes construction easier. After measuring and marking the deck area, remove sod from the staked area to a depth of 4" to 6". Replace the soil with gravel and level the surface.

Step 3: Install Posts

Using a line level, measure in from the batter board strings the distances given in the plan for the location of the posts. The depth of post holes are determined by local code, however, the post holes should be at least 24" deep and can be up to 4' deep. The actual depth depends on the height of the column and the depth of the frost line in your area, Figure 5. Posts need to be set deeper than the frost line to avoid heaving. Check with your municipality for local requirements for depth and width of post holes. Fill the bottom of the hole with gravel and place a treated wood block on the gravel. Set the posts in the holes, check for level and brace securely. Fill the hole with concrete or alternating layers of gravel and earth. Make sure the posts are plumb and in alignment with one another. Let posts set in concrete overnight (Figure 5).

Setting posts in-ground is the method recommended, but there are several options available. If you have rocky soil or a deep frost line, you may want to use one of the several types of pier blocks illustrated here. You do not have to dig holes when using pier blocks, and, depending on the type you choose, the posts can be attached in a variety of ways (Figure 6).

Post height is determined by measuring from the top of the deck to the ground plus the length of post set in the ground minus the thickness of the decking and the width of the joists. Height of posts that extend above the decking to support railings or benches is determined by adding the length of the post underground plus the distances from ground level to deck level plus the height of the railing, bench or features minus the width of the railing cap, seating boards or other materials.

Do not cut posts to their finished length yet. Allow extra length to accommodate setting.

Post Bracing

Perimeter posts over 5' high from ground to deck level need to be braced. While there are several methods of bracing, "X"-bracing is the strongest and is the method we recommend. In X-bracing, 2x4 or 2x6 boards run diagonally from just below the beams on one post to approximately one foot above ground level on the neighboring post. If the diagonal distance is less than 8', use 2x4s; if 8' or greater, use 2x6s. (Figure 7).

On corner posts, run the brace to the outside corner of the post, secure with 3/8"x4" lag screws or 3/8"x5 1/2' carriage bolts. Trim the end flush with the post. Braces that meet at middle posts are cut to meet at the center line of the posts (leaving a slight gap for drainage), and attached with lag screws or carriage bolts. Where braces cross between posts, fasten them with a single 3/8" x 3 1/2" carriage bolt.

Note: Post heights over 10' (ground to deck level) may require the services of a professional landscape architect or civil engineer.

Step 4: Attach Beams to Posts

Use a string and level to find the desired deck floor height on the posts. Subtract the thickness of the deck boards and joist (use actual dimensions not nominals) to determine the correct height for securing the top of he beam to the post. Make a mark on all four sides of the post at this point. Use carriage bolts to fasten the beams flush with the mark. You can cut the posts that do not serve as railing supports before attaching the beams. (Figure 8)

Step 5: Attach Joists

It is important that the surface of the deck have a rock-hard feel, especially elevated decks. To achieve this joists should be spaced a maximum of 24" on center. For decks over 6 feet off the ground, the maximum joist spacing should be 16" on center. Joists are attached to the ledger with joist hangers or by toenailing. They must also be attached to the beams and ribbon joists (Figures 9,10).

Blocking consists of 2x6 pieces nailed between joists to prevent buckling or twisting. Measure and cut blocking and nail through joists into ends of the block pieces. For ease of nailing, snap a chalk line across the joists where the blocking will go and stagger the pieces to the left and right of the line (Figure 11).

Step 6: Lay decking

Decking will be one of your deck's most visible features, so make every effort to lay decking boards straight and in line. Butt boards together because as drying occurs some shrinking can be expected. Also, when appearance permits, attach boards "bark side up" to help minimize cupping and warping. Attach the decking boards to each joist with a pair of 2½" galvanized screws.

If you use straight planing for decking, you can trim the deck boards after they are installed to assure a straight line. Snap a chalk line flush with or up to 1 1/2" out from the ribbon joist and trim with circular saw. For a more finished appearance, cut boards flush with the joist and add a fascia board.

In addition to laying straight planking, you can choose from a variety of different patterns for attaching decking (Figure 12). Diagonal or herringbone designs all add visual interest to the surface of your deck. These attractive patterns usually require slightly more material than straight planking. More cutting and attention to precision is required. (Note: the Deck Designer only allows for straight and angled planking).


Railings enhance the safety and appearance of decks and are required above certain deck heights. Check local codes. Railings must be sturdy and should be firmly attached to the framing members of the deck. They can be plain or elaborate and offer great opportunities for individual preference. Decorative ball tops and turned spindles as well as a variety of other specialty products are available to enhance railings (Figure 13).

Support for the railings can come from the continuation of deck posts that extend up through the deck floor or railing posts that are bolted to the outside joists or joist extensions. A common rail height is 42", but check for any special code requirements for your area. If you decide to use the deck posts, you may need to add intermittent or spacer posts for additional support. Never span more than 8 feet between railing posts. Check for any local code restrictions.

If you chose to attach posts to the outside joists or joist extensions, you must attach each post to the rim joist with at least two 3/8"x5" carriage bolts. For a finished look, you may want to bevel cut the end of the 4x4 post below the screw heads. Decorative handrail posts, spindles and handrail designs are available to dress up your deck.

Once the railing posts are cut to their proper height, you can install the cap rail and other horizontal rail members. Miter cap rails where they meet at right angles over a post. Galvanized screws should be used to attach the railing cap.


Probably no aspect of deck construction requires more care and thought than stair building, largely because there are so many variables that can change from deck to deck. The options shown here will help you get started. The following discussion is intended to help you plan and build a safe and attractive stairway customized to your particular requirements.

Decide how wide the stairs will be. They should be at least three feet wide, but often look and work better if they are wider. Check local codes to determine the maximum width allowed for stairs. You may need to add additional handrails on wide steps. For 2x4 or 2x6 treads laid flat, you will need 2x10 stringers at least every 42". Middle stringers must be cut; those on either side may be cleated or cut (Fig. 14).

For ease of construction, plan on 7" risers and approximately 11" treads, which can be made from 2x6s or three 2x4s.

Measure total rise to determine number of steps needed. Make the first step up from the ground 4" to 10" as needed to have all other risers be 7". Based on the number of 11" treads needed for the number of risers calculated, determine where steps will meet the grade - total run. Mark this point with a stake.

Both cut and cleated stringers must be cut to fit the deck and ground. Measure the diagonal distance from the top edge of the deck to the total run stake. Purchase 2x10 stringers that are somewhat longer than this distance so that they can be trimmed to finished shape when the tread-riser relationships have been worked out (Figure 14).

Measuring Treads and Risers

Mark the 7" riser and 11" tread distances on the two arms of a carpenter's square. Place the square so that it intersects the stringer edge at the two marked points. Mark stringer and continue for the total number of treads and risers needed.

For cut stringers, use a circular saw to cut the stringer to final shape. For cleated stringers, attach 2x4 cleats so that the tops are 1 1/2" below the marked tread locations to allow for width of the tread boards.

Cleated stringers can be toenailed to the box frame or bolted to posts added for railings. Cut stringers must be nailed or bolted to the existing box frame. In either case, the top of the cut or the top of the first cleat down must be 8½" below deck surface. Once the 2x treads are attached to the top step, you will have your 7" riser.

Stringers need support where they meet the ground. An easy support can be made with a 4x4 leveled in compacted earth or gravel; toenail the bottoms of the stringers to the ingrade 4x4. A small concrete pad can also serve as a suitable support.

Cut 2x4s or 2x6s to length, space as you would decking, and nail boards to cut stringers or cleats.

Add in-ground posts and intermediate posts bolted to stringers, as needed, to continue deck railing down the steps.

Multi-Level Decks

They may look, at first glance, to be complicated, but multi-level decks are really no more difficult to build than simple rectangular decks. In fact, a sophisticated multi-level deck can be nothing more than two rectangular decks joined together visually. Plan and build a multi-level deck with the following points in mind.

Generally, multi-level decks look best when one rectangle is clearly larger than the other. By all means, adjust the size of the rectangles to fit your own needs (Figure 15).

The simplest way to change levels is to build the second deck 7" higher or lower than the first. If you need a greater difference, handle the change with stairs, connecting deck to deck, as you would deck to ground.

Angling Corners

One simple modification to square or rectangular decks is angling one or more corners. Angling the corner will require extra posts and additional beam assemblies running diagonal to the 45-degree angle on the corner. The framing plan to the right shows where the extra posts and beam assemblies should be added. Angling all four corners will result in a hexagonal deck that is usually freestanding in the landscape (Figure 17).

Accessorizing your Deck

These are many ways to give your deck a custom look. Here are some ideas for a bench and lattice screen.


Benches add seating to a deck without taking up much floor space. They also help customize the deck.


Using pressure treated lattice (or aprons) around the perimeter of your deck really adds eye appeal. Lattice will cover the posts and framing and is a simple way to customize the appearance of your deck. Lattice is available in different sizes, and you may want to consider using special framing which is also available to hold the lattice in place.

Weathering Information

You will spend a lot of time and money on your deck and other outdoor projects. The lumber used around your home needs care and maintenance to help protect your project from the harsh effects of weathering caused by rain, sunlight and temperature change.

A high-quality wood preservative protects wood from fungal decay and termite attack. However, only a regular maintenance program can help minimize the effects of the weather on your outdoor project. Whenever a project is built with wood and exposed to the weather, certain inherent properties of wood become evident.

"Weathering" of wood is sometimes confused with fungal decay, but weathering is not fungal decay.

Here are some examples of what can happen to wood due to its natural properties:

Checks, Splitting and Grain Raising

These diagrams depict a cross section of wood, which displays some of the natural behavioral tendencies of wood. As wood is exposed to alternative cycles of wetting and drying, some checking and splitting may be expected.

Bowing, Crooking, Cupping and Twisting

These diagrams show some of the other ways in which wood reacts to weather exposure. Wood may bow, crook, cup or twist in varying degrees depending on stresses released by initial sawing of the lumber and moisture absorption.

Warping and Splitting

These diagrams depict a cross section of wood which displays severe warping and splitting. Severely warped or buckled wood is wood which has twisted to the point where it is an eyesore or structurally unsound. Severely split wood will have a crack that goes completely through the board and has opened. These severe warping and splitting conditions can sometimes be corrected, but in cases where the lumber cannot be salvaged, it should be replaced with new lumber.

Regular Inspection and Replacement

Severely weathered lumber that cannot be salvaged should be replaced with new lumber. It is unfortunate, but in spite of a homeowner's best efforts, including the application of weather resistant finishes from time to time, some pieces of wood due to the natural growing characteristics in the grain pattern will mechanically degrade as a result of weathering over time to become unuseful and unsightly. A homeowner's regular maintenance program should include periodic application of compatible weather resistant finishes and inspection of all fasteners to determine if nails, screws or bolts are working themselves loose. A nail which has popped out of the wood can be driven back or replaced with a screw and splitting boards can, in some cases, be reinforce with additional fasteners.

Reprinted with permission, Osmose Inc.

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