- Home Improvement
How To Build a Free-Standing Deck
Before you begin your deck project, you will need to do some research as to building codes and permits that may be required where you live. Some areas require a permit for any construction at all; others do not demand permitting for structures not attached to the house. If the structure is to be temporary, you probably will not need a permit, but it doesn’t hurt to check.
The very first consideration is the obvious one: do you have permission to build on the chosen site? Does the land belong to you? If not, do you have the permission of the landowner? (If so, get it in writing!)
Let us assume for purposes of this article that the land does belong to you.
Why would you want to build a freestanding deck? There are a number of reasons, but the two main ones are these:
- It may affect your property taxes, insurance, or both, depending on the regulations in your area. Some taxing agencies consider any attachment to the house as an addition of square footage of the residence, and use that as an excuse to raise your taxes.
- Likewise, most insurers consider an attached deck as part of the house, which may increase your insurance bill.
The project requires concentration, ability to measure, do simple math and observe safety precautions, but also needs a good deal of muscle power, be it by means of heavy equipment or a lot of strong friends and relatives who can be bribed with the offer of free beer and pizza.
Temporary or Permanent?
A freestanding deck can be built in either configuration. A permanent installation would require a foundation and footings, just as with building a house.
For a temporary deck, wood is the material of choice, and a poured concrete foundation is not needed. This would be a structure that you could leave up for extended periods, but also disassemble for storage or moving to a new location.
This is almost your only option if you are renting. Some landlords will allow modifications to the home, but most will not. In any case, as noted above, do not begin such a project without the landlord’s prior approval, preferably in writing.
- Concrete pier blocks (these are the supports that hold up the entire structure)
- 2” x 12” or 2” x 10” lumber for perimeter supports and floor joists
- 4” x 4” Redwood or pressure-treated posts (these go upright in the pier blocks to support the joists)
- 1” x 6” Redwood or composite decking planks
- 3” deck screws
- 8” x ½” carriage bolts and matching sized washers and nuts
- Joist hangers
sledge hammer or jackhammer (optional, if large rocks need to be broken up and removed)
mallet for driving stakes
circular saw and/or cutoff saw
drill-driver and Phillip’s head bit
Before You Begin
Consider the terrain at your proposed build site. If it is level or relatively so, you are in luck. If not, you must determine where you will have the least difficulty with slope. In this article, we will treat the project as being built on level ground because dealing with slopes becomes much more complex and not so much a DIY project.
If you find that you need a permit in your area, the permitting process usually requires a plan drawing to be submitted. For something as basic as a deck, a hand-drawn sketch of your own is sufficient for most local government agencies—no need to hire an expensive architect.
Ask your local agency about their requirements—some do not even require a to-scale drawing, but will want size measurements included, as well as plot layout of the project’s location in relation to the rest of the property. This is important, as there may be rules about how close to the property line you are allowed to build.
Style, Size and Shape
You need to scope out your yard and decide what would reasonably work. Also, take into account your own carpentry skills. If you are a beginner, the best plan is to stick with a simple square or rectangular shape, low to the ground. If you are at an intermediate level, you can try your hand at other shapes, and whether or not to add a roof or trellis top. If you are an advanced woodworker or professional, you don’t need this article. ☺
Given that every location is different, and different people will want different sizes, it is impossible to quote quantities., so I include only a general list of the types of materials. You will need to do measurements and calculations to determine the amount of material you will need; there are many variables. Refer to the sidebar for links to the American Wood Council and other resources to help with these calculations.
First, make sure there are no water or utility lines underground! Check with your local utility company, or call a locator service such as this one, that serves Northern California and Nevada.
Next, you must lay out your plot markers, then grade the site. This is done by means of stringing lines tightly between sturdy stakes marking the perimeter. You can either hire someone with experience operating a grader, or level your plot by hand (the size you have chosen will determine which option makes more sense). The latter option will need helpers with muscles. Even on level ground, there is still grading that needs to be done to insure a uniform base from which to work.
Use a line level on string wound tightly around stakes placed at intervals around your chosen area to be sure you are getting all your blocks and posts set at the same height. You can use the same markers as in your initial layout—just re-check for tautness and level. Run more lines across the middle in both directions for setting up supports inside the perimeter; how many will depend on overall chosen size.
Next, you will place your pier blocks, and insert your 4-inch x 4-inch posts into the tops. This provides the support for your framing. The larger the area, the more blocks and posts you will need. Generally speaking, you should have a support for every four feet of deck. This may vary by local ordinance.
Very important: be sure to allow for the 6-inch dimension of the joist lumber with the blocks inside the perimeter. You must adjust the height of the posts (easiest) or the setting of the pier blocks, to accommodate the lumber dimension, so the interior joists do not stick up above the exterior framing!
For your framing, use 2-inch by 6-inch lumber. All lumber used for outdoor construction should be either pressure-treated or redwood. With your overall dimension measurements in hand, it will be a simple matter at the lumberyard to determine quantity needed. A good lumberyard or large home-improvement store should have everything you need for the project.
Run the framing lumber around the outsides of the support posts, being sure to stay level. Keep checking your line level. Bumps, stumbles, and dropped tools or materials can easily knock your line out of whack.
Attach the framing to the support posts with bolts run all the way through both the framing lumber, brackets made for the purpose, (called joist hangers), and the support posts. (This construction is referred to as “through bolts.”) Holes for the bolts must be pre-drilled all the way through. The easiest way to get the holes lined up in the correct place is to use large C-clamps to hold the wood, joist-hanger bracket and post all together, then drill through the entire thickness using the holes in the joist hanger as your guide.
Run the bolts through, fasten on the inside with washers and nuts, and remove the clamp.
It is best to avoid seams or joints in a linear run. 2-inch by 6-inch lumber can be had in lengths as long as 20 feet. Plan ahead.
Checking for Square
Your finished project must be square, and not tweaked or warped. After the framing, but before the joists are added or the decking or sub-floor is laid is when this needs to be done.
For a large area, the easiest way to check for square is to measure the diagonals. Measure one diagonal, note the distance, then measure the opposite diagonal. The measurement should be the same.
If it is not, have helpers hold one corner while others shove the frame against that direction. Repeat the measurements until they match. If the first re-check of the measurement shows a bigger discrepancy, you shoved in the wrong direction. Push from the other side, and re-check measurements. Repeat process until the measurements match.
Remember to account for the thickness of the wood in your calculations, and remember that the stated dimensions are of the rough-milled size, and not the finished size.
For example, a 2" by 4" (stated as 2x4) piece of lumber is actually only 1 - 1/2" by 3-1/2".
Joists are the 2-inch by 6-inch members that span the middle space inside the frame at right angles to the frame, across the short dimension. They must be level with the top of the frame. Use joist hangers on the insides of the main support posts of the frame, with the bottom of the bracket at 5 and ¾ inches below the top of the post top. The interior posts need to have their tops set at a height 5 and ¾ inches below that of the exterior posts, as the joists spanning this space will sit on top of the posts, and not be hung from their sides.
There are special brackets also which cap the posts and have flanges to hold the lumber atop. These brackets have holes pre-drilled for attaching to the posts and to the lumber which they support. Depending on the manufacturer, there may be some variance in the thickness of the metal in the brackets, requiring an adjustment of 1/32nd to 1/16th of an inch in the mounting height .
Measure the thickness of the bracket prior to setting the interior posts! These are small differences, but enough to cause your joists to stick above the frame. Even a small projection above the top can cause headaches.
Foundation Elements (click for larger view)
Various sizes of lumber can be used for the decking planks. 1-inch by 8-inch or 1-inch by 6-inch or even 1-inch by 4-inch can be used. Just remember—the narrower the planks, the more you will need, and the longer time you will spend fastening them all down.
You can choose either a straight or diagonal decking pattern. Straight is obviously easier, as you will be making only straight cuts, and not have to worry about cutting a bunch of 45-degree angles to get a diagonal pattern. Also, cutting diagonals uses more material as there is considerable waste.
Decking must be laid with spaces between the planks to allow for expansion and contraction of the wood. The spaces also allow water to drain through, instead of accumulating to cause rot. Use a spacer to get uniform placement. A spacer should be an 8-penny nail or equivalent width.
The spacing serves a secondary purpose: through the openings, it is easy to find the joists into which you must screw the planks. Run the planks at 90 degrees to the joists. In any case, be sure to mark a line at the center of each joist onto the outside of the frame for reference.
Once all the planks have been screwed in place, coat with a waterproofing sealer, allow to dry and enjoy!
The plank decking can be your finish step, but you could also install a solid surface top, using the planking as a sub-floor. A solid-floor would be a good choice should you wish to use it for a tent platform, for example.
For this option, use exterior grade T & G (Tongue & Groove) plywood. Order as “one side good.” This will cost less because it means only one side if finished off to have a nicer-looking surface: you don’t care about the appearance of the side facing the sub-floor or the dirt below. For this option, you could simply use the plywood alone, and omit the planks, saving both time and money.
Screw down your plywood sheets, using a spacing of 6 inches apart on the perimeter and 8 inches apart in the field (that’s the term for rest of the sheet). Be sure you mark the position of each joist on the outside of the frame, and snap a chalk line from those marks across the top of the plywood, as screw guides.
Give the entire surface a thorough sanding to eliminate splinters, and coat it with a good waterproofing agent.