This is the second part of a series of articles that describes the steps to build a deck.
In the first part, I described several things that you need to focus on before you design your deck on paper.
Now that all of the planning is out of the way, you can begin the process of actually building the deck starting with cleaning out the area where the deck will reside.
Marking the Deck Area
Before you locate the area where the deck support posts will go, you need to mark the area using batter boards and string making sure that you have the correct measurements. It is crucial that you make this square. Hammer the batter boards in the ground just outside of the lines where the deck will reside. The string will act as another visual cue to help you see how and where everything will go.
Here are the steps:
- Attach a string to your house where the joists will hang.
- Check for square in the corners using geometry. Use a black marker to mark 3 ft from one corner on the string and 4 ft from the other side of the corner. The diagonal measurement across these two points should equal 5 ft. If so, you have a right triangle so the corner is exactly 90 degrees.
If you are attaching your beams to the support posts as I did, the posts will be set at these corners. That is where your cement footings will go and the support posts will rest on top of the footings to keep them off the ground and away from moisture. Even though the posts are pressure treated, they will not last forever if buried directly into the ground. As I stated in the first part of this series, I buried my posts, but I will be replacing those with another beam support method, perhaps a cantilever style support system.
Speaking of cantilever decks, if you want to create a deck of this style, your deck will overhang your support beam, hence the cantilever name. So you will locate the cement footing a foot, perhaps two feet, in from the edge of your deck beam.
Using a spade shovel or similar device, remove any sod that will be covered by the deck plus an additional 2 feet around each side. Use the sod in other areas of your yard so that it does not go to waste. Simply lay it out and water it immediately. Continue to water every day. Sod does best in full sunshine.
If you are concerned about weeds growing under the deck, you can spread landscape fabric and cover with gravel.
Attaching a Ledger Board
Once you have the area cleared, you can proceed one of two ways depending on the type of deck you are building. I will assume you are building it up against your home, however, that is not always the case. For instance, I already had a deck built on my house, but there was a screen-in porch that covered most of the deck. So I decided to extend a deck out from the original deck. I simply attached the joists to the existing end piece of the original deck so no ledger board was needed.
However, if you are building a new deck or replacing an old one from scratch, you will be attaching a ledger board to the cement foundation using expansion bolts. You will need to use a hammer drill and masonry bit to drill into the cement blocks of the foundation, and then hammer the bolts through the wood ledger into the holes in the cement.
If you are attaching it to wood, secure it with bolts all the way through the boards, or use lag screws. Be sure to inset aluminum flashing in the appropriate manner to keep water from getting behind the board.
When attaching to a home with Hardieplank, aluminum or vinyl siding, you will have to cut away an area in the exact dimensions of the ledger board. Do not attach it through the siding of any kind.
When attaching the ledger board, be sure to account for the added height of the deck board that will eventually be laid across the joists. Therefore, you will need to have the ledger board about 1.5 inches below the actual height that you want the deck.
This process sounds complicated but it is not. As I said, I did not build my deck this way because I extended my deck from an original deck. If you would like further instructions on how to attach a ledger board to your foundation, see the video below.
How to Attach a Ledger Board
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Locate and Dig Footing for a Deck
Since you already laid out the outline of your deck using string, you already know precisely where you will need to dig. Again, this will depend on the type of deck support system you decided upon, but I will describe the process I used.
When you dig the holes for the posts or footings, they should be twice the size of the actual posts and go below the frost line to prevent repeated freezing and thawing of the concrete.
In most areas of the United States, you need to go down 18 – 24 inches. The local code in your area will determine this as described on the permit.
I supported the end of my 22 foot deck with four 4x6 pressure treated columns buried directly in the ground.
To start, I poured a couple of inches of gravel in each hole for drainage and then placed each post in the hole. Next, I whipped up enough concrete to fill the hole around the column making sure that the post was plumb as it begin to dry. Use a 36 inch level to verify each side is perfectly plumb.
Alternately, you can create a concrete footing that is exposed above ground using a cardboard circular mold called a sono tube. The advantage here is that the wood never touches the ground. These come in 8, 10, and 12 inches in most home improvement stores. Choose the appropriate size based on the size of your support posts.
I should mention that at the end of my project, I had several pieces of 4x4 posts leftover, so I went underneath my deck and dug holes to bury them in cement. I attached them using a lag screw to various joists just to give it added stability and support.
While the concrete is drying in the tube, attach the J-bolt hardware in the concrete. This is what holds the posts to the concrete footing as shown in the video below.
How to Build Deck Footings
Attaching Frame of Deck
After your footings have dried for a day, then you can attach your frame beams from the ledger board to the posts. For this task you will need string and a level. Or, if you have a helper, you can extend a board the length from the ledger to the first otter posts to mark the height. Remember, you need to account for the height of the deck board, about 1.5 inches, when determining where to hang your first frame beam. Before permanently attaching it to the posts with lag screws or bolts, use a 48 inch level to make sure it is straight. In fact, it is ok if there is an ever so slight angle away from the house to allow from rain water to run away from the home.
Beams can rest on top of the posts or be attached to the side as I did. I used long bolts to go all the way through the beam and the post, approximately 8 inches. You will definitely need an electric drill and a long bit for this one. Secure both sides with washers and tighten a bolt on the inside for each.
I initially attached my frame beams to the posts in this matter, however, a year later I made a slight modification. I used from scrap 2x6 piece of lumber to attach each to the outer part of the support post using bolts all the way through underneath the frame beams, essentially thickening the support post and resting the frame beam on the new edition.
I also dug out around my footings, bought some sono tubes and created an above ground footing to help hold each post together. The posts are still buried in the ground, but each has exposed concrete now.
Again, if I had it to do over again, I will set the footings on concrete and use hardware to secure it in place. However, when I first built my deck several years ago, I had no experience building anything like this, so I was eager to get started the quickest way.
Once you have attached both frame sides protruding from your ledger board, you can attach the header board of the deck at the other end. Now you have a perfect square or rectangle to work with going forward.
Now that you have a solid support system built, you can begin the process of actually creating the top of the deck using deck boards, building the steps and deck handrails for a finished look.
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