How to Build a Simple Deck?

A popular service request from many of our clients involves constructing either a ground-level or rooftop deck.

Investing in any type of deck structure provides many dividends for the homeowner.
A beautifully built deck can enhance property value, and provide an enormous amount of enjoyment for one’s family, and for entertaining.

It can also serve as an extended living space during the warmer seasonal months.

Decks can be elaborately styled with many details and nuances to make them unique; which can contribute to a higher price point. A simple deck design can be quite affordable, and can serve as a starting point, if in the future; the homeowner decides to add on or add additional features to the deck.

One of the first steps for one considering the installation of a deck is to list what activities the deck may be used for. This can be important when considering the structural requirements.

If for example; there will be a large number of persons on the deck at once, the deck must support the load, and should allow for people to have a comfortable space to move around on. If outdoor cooking and dining are important elements in the design; locating such areas near the kitchen, or establishing a dedicated space for the intended purpose, should be incorporated into the design plan.

Also important is to consider the design aesthetic of the home. Should the deck look traditional? Should the deck build have a modern design?

Once a wish list has been established; the next decision is to choose the type of materials to be used for the deck build.

Type of materials

The most economical option for the undercarriage of a deck build is treated lumber.

For a basic rectangular deck; a minimum size of 2”x8” lumber can be used, providing that the floor joists are spaced no more than 16” on center. If using such sized lumber; one should not exceed four feet past the outer-most supporting beam, or support piers for the deck. (The area described is known as the cantilever).

Two by eight inch lumber tends to be the most common choice for ground level decks or decks which do not exceed 24” in finished height. Such decks often do not require a permit as long as they are not secured to the main dwelling structure.

For many typical deck installations, a permit is required; and one should always check with local building authorities to verify what size of deck may be permitted, and what support structure will be acceptable.

In order to obtain a permit, and to obtain pricing from a contractor whom may build your deck; a detailed drawing should be created to demonstrate the design of the new deck build, and to reflect the key components being used in the structure of the deck.

If one has moderate competency with tools, a simple deck build can be achieved by the homeowner.

Related Content: Choosing Deck Materials for Your Deck

The steps involved to build a deck include

  • Decide on the design elements required for the deck including your choice of materials.
  • Draw a detailed sketch or sketches (drawn to scale if possible), to reflect all of the materials and related sizes required for the build. If you are challenged in this regard, a qualified contractor may be able to supply such drawings for a fee.
  • If attaching the deck to the dwelling, supply a house drawing with all related home and lot dimensions. (This will be required to obtain a permit).
  • Check the local building authority website to verify requirements to be compliant with size restrictions, location, and height restrictions, etc. Better yet, contact your building official to obtain their advice and recommendations.
  • Provide photos of the site and location where the deck is to be built.
  • Submit all required drawings, photos, and lot plans to the city/municipality and apply for your permit. A fee will apply.
  • Prepare a list of the materials and sizes required, for placing a lumber purchase order. Delivery of materials is the most convenient option, but it is highly suggested to visit the lumber supplier and select your own pieces, to insure the products are best quality and true, void of twists or checks in the wood materials.
  • Once approved; contract the work to a competent deck constructor/carpenter; or prepare to begin building it yourself.
  • Recognize your limitations. Make sure you have the skills, labour support, and time necessary to pull off the project. If not; hire a professional with proper WSIB and liability insurance coverage.
  • If attaching the new deck directly to the home, be sure to inspect for hidden conditions (rotted wood behind siding as an example).
  • If installing concrete piers, or digging for alternative supports; you must contact a utility locate service to verify the locations of under-ground gas lines, service utilities, etc. Failing to complete this step can have dangerous consequences. Never assume the digging area is safe.
  • Once professional locates are completed it is time to layout the deck and get started on the build.

Laying out a new deck

There a few basic principles one must follow when laying out a basic deck.
That is to construct everything plumb, level, and square.

You will require:

  • Surveyor’s string
  • Plumb bob
  • String level
  • 4’ long level
  • Hammer
  • Screws
  • Screw gun
  • Wooden stakes
  • Marking pencils /markers.

Although a pro can do a deck layout by him /herself; it can be a good idea to have a helper at this stage for holding items.

Determine a starting point. As an example we will assume we are building a deck exterior to a kitchen sliding door. When entering onto the deck from the kitchen, it is logical to have one step down onto the deck as a comfortable step, and to allow for winter snow accumulation.

We will assume the height of an average step to be 7 ½” inches. So step one will be to make several marks 7 ½” below the sill of the sliding door, and to draw a line using the level; to mark where the ledger board for the deck must go.

As the line now marks the finished height of the deck surface; string lines can be extended out away from the house to demonstrate the exterior perimeters of the deck; by placing the string level on the string line, and extending it beyond the intended exterior dimension of the deck.

The leveled string line may now be attached to a stake which has been driven into the ground, and where the string may be wound around the screw driven into the stake, at the correct deck height.

To insure the string line /stake is accurately placed, in a square configuration; use the 3-4-5 rule, to make the line square. On the original line drawn beneath the door sill, mark 3 feet in from the corner.
On the string line that extends outward from the deck; tie a piece of string onto the existing string line and place it at 4 feet. Using a tape measure open to five feet, lay the tape measure between the two mark points. A perfectly square corner should result. Once confident of the correct line location; secure the stake into the ground. Double check the string line is level and adjust as needed.

Repeat the process on the opposing side of the deck. Then connect the two outer points that have been established, by connecting a third string line between the two outer points. The result is that you will have the outline of your deck, with the finished height marked, with all points level and squared.

The next step is to determine where the support post will be placed. We will assume the deck is 12’ deep and 24’ wide. Discussed, is that the cantilever of any deck should not typically exceed four feet in any exterior direction. Based on 12’ extending away from the house; the support piers should then be set 8’ away from the house wall.

Based on the deck being 24’ wide, it is suggested to have a minimum of three piers spaced evenly apart; starting with the middle pier being centered on 12’ (half of the deck width). The two remaining piers should be centered 2’ away from each side of the deck, resulting in a 2’ cantilever on each side of the deck. Additional piers or a row of piers can be added in a similar fashion, if the deck will be higher than four feet above the ground and where the deck may be required to support a great deal of weight or accessories.

In the above example, we are assuming the deck is under four feet high, and that the deck will be secured to the house wall itself.

By placing another string line across the width of the deck at the 8‘ mark; measuring from the house wall, this provides a straight line reference point to centre the piers.

Using a piece of sono-tube to mark the location of each of the piers; measure the appropriate distances, and place the sono-tube in the prescribed locations. Spray paint around the perimeter of the tubes; which will result in a clear marking of the support pier locations.

The next step involves digging the holes for the piers. Using a power auger,( which can be rented); bore the required holes insuring that you dig beneath the frost line (typically four feet in Eastern Canada and the U.S.). Note that having a second person help man the auger is a good safety precaution, as the tool may kick back if not held securely. It may also be necessary to use a “clam digger” shovel to remove the residual dirt in the bottom of the holes.

Place the hollow sono-tubes into the hole. Cut the sono- tubes at sufficient height to allow clearance for post saddles (metal support brackets), and or timbers which will form part of the structure.

To pour the piers correctly involves first placing aggregate in the bottom of the holes. At least 6” to 9” of rough aggregate is suggested to allow for drainage, and for the concrete to grip. Pour bags of dry ready mix concrete into the holes; fill to the top of the sono-tubes. Gradiently add water, and mix using a tiny head spade, stick, etc. to agitate and mix the concrete. One can also premix concrete in a portable mixer or wheelbarrow and add the concrete gradiently into the tubes, as an alternative measure.

Once the concrete has been poured, and is beginning to become firm, place in the steel post saddles. The saddles need to be placed in a symmetrical line centered in the same direction as each other, Using a string line can help to align such. When all is dry, framing work can begin.

Framing the Deck

Starting at the house wall; remove any siding carefully, beneath the original level line. Make sure to transcribe your original line if the siding has to be removed in the area of the original marking.

The next step is to insure the wall surface is sound, by correcting any deficiency in the wood wall. It is a good idea to install a water-proof membrane on the wall surface for future protection from snow, ice or water ingress.

The next step is to subtract the depth of the finished deck surface material, and mark a new level line beneath the original line marked on the wall. If using 5/4” deck boards as an example; deduct 1-1/4” from the original line drawn at the wall, beneath the sliding doors.

The new line will represent the top of where your supporting deck lumber should be placed. Using 2” x 10” pressure treated boards; place two- 12’ lengths immediately below the newly marked level lines; side by side, and one at a time. This is where help is necessary to hold the boards flush to the marked line.

Drill pilot holes in the board and wall approximately every 12”. And stagger the holes alternatively higher and lower for each “pilot” hole. The pilot holes are designed to make it easier to install the lag screws, which will be responsible for securing your “ledger” board to the wall.

Using the correct length of lag screws (which need to be the depth of the framing lumber and a sufficient length to attach through wall sheathing and or supporting wall framing lumber (Typically no less than 4 inches); begin installing the lag screws, using a socket wrench or a socket on an impact screw gun.

Once the ledger boards are secured along the length of the house wall; install the upright supports from the piers.

Using 6’x6” pressure treated posts, secure them into the post saddles using 3-1/2” exterior deck screws.
Be sure to use a level to insure the up-right posts are plumb and level from side to side and front to back. Cut the piers initially so that they are a manageable length, but allow enough length that they can be cut flush to the appropriate height later. As an example ; an 8’ post could be cut into two four foot lengths, assuming you will not require the posts to exceed 4’ high.

Install additional lag screws into the supports for increased structural support.

The next step involves installation of the outer support beams.

On the upright support posts (in this case three);mark a level line across the front and back of the posts, at the same height as the top of your ledger board at the wall. Measure down on the posts from that point, the depth of a 2”x10”. The measurement will actually be 9-1/2” below your initial marking lines. Scribe those measurements on all four sides of the posts.

Next; secure using lag bolts, 2”x10” boards on the front and rear of the upright support beams. Check to insure both of the upright posts and the new “beam” boards are plumb and level. Long deck screws may be used to temporarily secure the beams in place, until lag bolts can be installed in the same fashion as doing the wall ledger board.

On the ledger board and the support beams, mark 16” centers; measuring from the outer edge of the boards. The centre points marked, serve as the locations for all of the floor joists. The next step of installing the floor joists requires the help of an assistant to hold the boards in place while securing them.

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In the case of this deck having a depth of 12’; using 12’ lengths of 2”x10” lumber as the floor joists makes the job simple. As the deck is 24’ wide; install two,2”x10” boards side by side, at the 12’ mark (half the deck width). This will serve as the support “spine” of the deck, lending extra strength at the centre point of the deck. (It also permits that the floor joist may be run in an opposing direction, in the event one wanted the deck boards to run in an opposite direction). Install staggered lag screws into the doubled centre spine.

When installing the remaining floor joists,use deck screws. Drive one screw on an angle, in through the top of the floor joist in order to secure it to the ledger board. Make sure the floor joist remains flush with the top of the ledger board. Make sure that the opposite end of the floor joist is resting on the double beam, and that the floor joist is centered on the opposing mark made previously. Using an upright metal joist hanger; secure the hanger to the beam with hanger nails, pinch the bracket tight on the floor joist ,and secure the rest of the bracket to the floor joists.

Back at the wall (ledger board), repeat the process using a metal joist hanger designed for that purpose/location. Simply repeat the process for all floor joists until reaching the outer perimeter of the deck.

The outer frame members of the deck are referred to as the rim joists. Rim joists can be installed prior to installing all the floor joists, and typically are by the pros. Secure the two sides and end boards, insuring to use corner joist hangers where the floor joist will meet the outer rim joists.

When installing any dimensional lumber such as the floor joists, it is important to place the “crown” of the wood on the upside. The crown refers to the fact that natural milled lumber may be higher toward the middle of the piece. The high end will settle in time, with weight on the deck. By casting one’s eye down the length of a board, one can see if the board has a crown side.

When cutting any treated lumber, it is wise to treat the cut ends with a preservative coating, which helps prevent future rot.

With the supporting frame now in place; the addition of “bridging” between the floor joists can add strength,and help eliminate the feeling of bounce,especially when there are a number of people on the deck.

Cut pieces of floor joist material or use cut off pieces to form bridging pieces that will be placed in between the floor joists. For floors that have 16” centers, cut the bridging at 14-1/2” lengths.
Stagger the bridging materials when installing the pieces; typically at one quarter of the span of the floor joist. In this deck example; every three feet, will make the floor very strong. Deck screws are perfect for the task.

Decks which are above 24’ inches high require a railing by building code standards. Railings should be constructed a minimum of 42” finished height. If using pickets in a railing design; they should be spaced no more that four inches on centre,also a code requirement.

While there are many different railing options in terms of design, and product types such as wood, metal and glass; we will discuss a basic wood railing structure.

Railing supports can be made using 4’x4” treated materials. The supports need to be cut to allow for the depth of the floor joist as well as the height above the finished surface of the deck, but less than the finished hand rail material. If we use the same 5/4” boards for the hand rail ( similar to the flooring material); we would need to cut the posts to a height of 50-1/4”.

As the deck is 24’ x12’; there will need to be 8 posts to surround the deck at an even span of 6’ on centre between posts. (12 if incorporating stairs). The posts must be notched out using a power saw to sit flush to the exterior surface of the rim joists. This involves cutting out 1-1/2”x 9-1/2” at bottom of each post.
Both deck screws and lag screws or lag bolts should be used to secure the posts, insuring that each post is level front to back and side to side.

Between each six foot post section, and internal “ picture” frame can be constructed using 2’x4” materials. It will consist of a top rail, kick rail,and two side rails. The sections should be constructed to allow at leat 2” of clearance.

To learn more about ground or roof decks, restorative exterior carpentry, and other related services, contact our Construction Team or visit us at: