How To Plan and Design a Wooden Deck

How To Plan and Design a Wooden Deck

How to Plan a Deck

Most folks use a deck as the central gathering and entertainment focus for their entire back yard. Therefore how the deck is designed becomes critical. If planned correctly, your deck will custom fit your house, your terrain, your lifestyle, and your budget. Plan your deck carefully now and years down the road you will be glad you did!

Considerations, Problems & Pitfalls

Question: «What kinds of things should I be aware of as I plan my new deck?»

Answer. How will you use your deck? For example, do you need lots of room for entertaining large numbers of people? Will there be sunbathing? Cooking on the deck? Small children? Will the deck lead to a pool? Will a spa be added to the deck? Will a screen porch be added in the future? Will you want permanent seating? Flower boxes? If so, will you want flower boxes on casters to make them moveable? Need privacy from neighbors? A special place for your grill? How much do you hate maintenance (periodic deck sealing)? Is the view from the house critical? If so, from which room(s)? Will you want stairs? If so, what are the traffic patterns from the house to the yard to consider? Is your deck going to be high enough that you will need an intermediate landing in the stairs? Will you need additional lighting to illuminate stairs at night? Will a self-latching gate be needed?

Question. «Where should I locate my deck?»

Answer. In most cases, that will be answered by where your door is located at the rear of your house. In some cases, folks will want to consider adding a door (installing a door the same size and at the same location of an existing window makes the job easier and less costly). Most decks follow along the back of the house, working around such things as hose bibbs, dryer vents, chimneys (never attach a deck to a chimney or to a cantilevered bay) and downspouts. Check with your local utility company or heating and air conditioning company (or heat pump manufacturer) to determine how much clearance you will need above your heat pump or AC unit if you plan on decking above it. You do not want to lower it’s efficiency. You can deck around them, but be sure to leave a foot or two to allow room for access. In locating a deck, you will also want to consider what is buried in the yard. Do not cover a well, propane tank, or septic tank with a low level deck without designing in proper access panels into the deck. Also, where the sun comes up and sets and when and where shade is available should be considered when choosing location. Also, certain trees can produce very annoying sap drippings and leaves that stain a deck. Minimizing noise (and nosiness) from neighbors and passing road traffic may also help you decide to locate the deck in a more protected and private area. Similarly, your view should be taken into consideration. A high deck allows you to see, but not be seen as well.

Legal Stuff

Question: «What kind of legal considerations are important?»

Answer. Check with your local Zoning Department to determine how close you can come to your side and rear lot lines with your deck. Sometimes they will allow stairs to come closer than the deck. Sometimes a so-called «free standing» deck can come closer to a lot line than a deck attached to the house. Ask if they have anything they can give you in writing. If you are blessed with an HOA (Homeowners Association), ask them for up-to-date covenants that spell out any restrictions on size, location, and appearance. Trust me. it’s better to know now rather than plead ignorance later and wind up re-doing your deck. Ask your local Building Department if they require a building permit and a set of Building Plans. Call your local utility companies (gas, electric, phone, cable) and ask them to mark buried lines or pipes in the yard and to notify you is they have a utility right-of-way on your property that prohibits constructing a permanent deck.

Size Matters

Question. «How large a deck should I build?»

Answer. That will depend upon many factors including how large your house is, how small your yard is, if your hot tubs on it, how much you want to spend, and what you will want to do on the deck. Don’t plan a deck too big for your house. And if your yard is small, you may want to keep some yard available for landscaping. To get a feel for how large the deck should be, try using string to line the perimeter of the deck. Then place some deck or lawn furniture in the designated area to see how useful this space will actually be. Will there be enough room for a table and chairs? A grill? A separate sitting area needed? You will likely only build this deck once. Do it right the first time. and don’t make the common mistake of building it too small. Five years from now you won’t remember what you paid for it. but you’ll darn sure know if you made it too small. Another good point to remember in planning size is this: Plan the distance out from the house in even 2′ increments. Normally your floor joists will be perpendicular to the house wall and wood lengths come in even numbers. Don’t waste materials if you do not need to.

Design Enhancements

Question. «Are angles and level changes and different decking patterns good to use? Or will it run the cost up a lot?»

Answer: A deck can be built in just about any shape and with multiple levels and deck boards run on a 45 degree angle (or even alternating in a herringbone design) really adds aesthetics and strength to a deck. But, yes, any of these design enhancements also add materials cost and normally also labor cost as well. Don’t even ask me to estimate how much more. Maybe 5%-25% more depending on what design enhancements you want.

Height Matters

Question: «How high should I build my deck?»

Answer: Typically build a deck no higher than about 4″ below the door threshold. You don’t want water to gain entrance to your house. Sometimes to gain more view from the house, or to attach a deck to a solid concrete foundation wall (as opposed to attaching it to a thin house floor joist plywood band), it is preferable to build a step in front of the door and lower the deck 14″ to 16″ below the door threshold. Check with your local Plan Review to determine if a deck over a certain height will require cross bracing to increase stability. If your land slopes down, you may want to build in level changes to follow the terrain. It looks very cool. but it runs the cost up.

Spas & Hot Tubs

Question: «What special considerations should I make for a hot tub or spa?»

Answer: Water weighs 62 lbs per cubic foot, so if you plan on setting your spa on top of your deck, when it’s full of water and people, it’s the equivalent of an elephant on your deck. It needs proper support. You will definitely want to hire the services of an architect, engineer, or deck design firm to help you with the additional support requirements for a spa. Your local Plan Review should also be able to help. (Your taxes pay their salaries remember. They can help you by working out some calculations to properly support your spa.) On the other hand, you may want to rest your hot tub on a concrete pad and build the deck around it. Here’s where things also get tricky because you must insure that the deck is properly supported. And don’t make the mistake of sinking the spa flush with the top of the deck. That first step into the spa may be so much lower than the deck surface that folks fall into the spa! (Which may be funny until it’s your wife.)

Cut Outs

Question: «How about cutting out the deck to go around things like trees?»

Answer: It looks great. Just make sure that you take into account such things as how much the tree will grow and how much it will sway in a typical high wind. Don’t frame and deck too closely. Leave slightly less than 4″ on all sides. You will want to make a kind of collar that fits around the tree and «floats» on the deck. Such a collar can prevent someone from stepping into the gap while allowing the tree to sway. Also a bench around the tree (planter box?) is a possibility. Check with a local Building Inspector or your Plan Review to determine if their are safety issues they will want addressed.


Question: «What special considerations should I be aware of for my deck’s handrail?»

Answer: Check with your local Plan Review to determine at what elevation from the ground your deck actually is required to have a handrail. Typically it’s 30″, but localities may differ. But even if you are not required to have a handrail, if you choose to install one, it must meet code requirements. That means the openings must be only so large (code changes periodically, but as of this writing most localities typically require that a 4″ diameter sphere cannot pass through it) and the main support posts (usually 4x4s) cannot be too far apart (5′ is typically the max). The handrail must be of sufficient strength to sustain both lateral and vertical forces specified by code. Here again you will need an architect, engineer, deck designer, or local Plan Reviewer to help you with what handrail designs meet or exceed code requirements.


Question: «What do I need to know about designing stairs?»

Answer: If your deck will be high (say 6′ or higher), you will want to consider installing an intermediate landing for safety and aesthetic reasons. Step and stair construction is very carefully regulated by code requirements, so you will want to work closely with your local Plan Review in order to build to their specifications. As of this writing, code typically calls for stairs to be no less than 36″ wide (from inside of handrail to inside of handrail), have a banister (grab rail) down at least one side, have riser and treads limited in dimensions, a 1/2″ to 1″ stair nosing, risers enclosed, 2×12 stair carriages appropriately spaced (18″ in some localities). Again, work with an architect, engineer, deck designer or your local Plan Review to obtain a detail drawing of a typical set of stairs. As with all of your deck, you will want to build stairs to meet or exceed code requirements.

Basic Components

Question: «What are the basic components of a typical deck?»

Answer: A deck is normally composed of vertical support posts that rest on buried concrete footings. Code typically limits how far apart these support posts can be spaced. Each post supports beams (girders) that normally run parallel to the house. Again, code dictates how far apart beams can be from each other otherwise you will over span your floor joists. The beams support floor joists that normally run perpendicular to the beams. Normally floor joists are spaced 16″ OC (on center meaning center to center) but may need to be spaced closer under certain circumstances (ex- if using certain composite decking diagonally). Sometimes floor joists can be spaced further apart. Joists distribute the weight of the deck boards above which are run either perpendicular to the floor joists or on a 45 degree angle. The last deck component is the railing which is normally 36″ to 42″ high. Code will dictate the materials, design and spacing for railings and for all components of a deck. Always submit all Building Plans to your local Plan Review before building.

Building Materials

Question: «What kinds of deck building materials are commonly acceptable?»

Answer: There are more and more materials being used today, but take into consideration whether or not the materials are resistant to decay and insects (CCA pressure treated wood is as also is cedar and redwood. but not as much). What are the effects of water, sun, heat and cold? Some composites and plastics do better than wood in this area. but some composites «creep» with heat (meaning the deck boards actually sag between the joists). Some plastics are very user unfriendly to install whereas many composites cut, nail, and screw like wood. Wood (any kind of wood) left exposed to the elements will turn gray unless you apply an excellent sealer. But sealers are expensive and must be periodically re-applied. There are no easy answers. but there is a simple answer: Do your homework. Read, study and talk to the experts.

How To Plan and Design a Wooden Deck

Costs to Contract

Question: «If I contract a deck out, how much should I expect to pay?»

Answer: Naturally the prices will vary, but a fair price range currently is from $18-$25 per square foot for a turnkey standard pressure treated deck. Turnkey means they provide labor, materials, building permit and you don’t lift a finger. You can find deck companies that will charge less currently, but be careful. Sometimes a home improvement company falls into the trap of thinking that they can lower their prices to where they get a lot of business. but wind up so busy and making so little on each deck that they become frustrated and go out of business. leaving you to deal with any future problems.

Costs for Materials

Question: «Suppose I want to build a pressure treated deck myself. How much can I expect to pay for materials?»

Answer: Again, prices vary. But a fair price range right now is from $5.00 to $7.00 per square foot for pressure treated deck materials (including fasteners and concrete).

Costs (Labor Only) to Contract

Question: «And if I want buy the materials and have a good deck builder build it for me. how much should I pay?»

Answer: If you have the deck design (so no salesman needs to be paid a commission), are willing to obtain your building permit and buy your own materials, you are saving the deck builder a lot of overhead expenses. So it is natural to expect a sizeable discount. The amount of that discount is naturally a very negotiable quantity. but my firm offers a 25% discount off our current turnkey prices of $18.60 per square foot. As I said, companies will vary, but we will build a typical pressure treated or composite deck for $7.95-$8.95 per square foot labor only. But then you must add the cost of materials and your building permit. Most folks find a savings of about $2000 on the typical deck by using this interesting homeowner interactive program.

Fitting the Deck to the Budget

Question: «If I am on a budget, how can I design a deck and know I’ll come pretty close to how much I can afford?»

Answer: Simple actually. Take the total cost per square foot and divide it into your budgeted amount. Example: Suppose you are building the deck yourself and you are using pressure treated materials. Let’s say you have a $6000 materials budget. Divide $6000 by $6.00/SF (approximate cost of materials) and you get 1000SF of deck. That’s a lot of deck, by the way. 500SF is more typical. If you are hiring out all or part of the labor, you must add into the materials cost of $6/SF the cost of the labor. But this will help you determine how large you can design your deck for a given budget.

Getting Started

Question: «OK, but how do I get started?»

Answer: You will want to make a sketch on 1/4″ graph paper. Splurge and buy a pad of the 11×17 paper. Draw your house wall to scale (overhead view. like a blueprint). Draw in the windows and doors to scale (accurately placed on the drawing). Include such things as a heat pump, chimney, bay window, hose bibb, dryer vent. anything that may impact the deck (including trees or even a septic system). Include an elevation measurement from the ground to 4″ below the door threshold. If you know where you will want your stairs to go, make an effort to determine how high it will be from the ground at that point to 4″ below the door threshold. A line level and length of string works great for this measurement and costs very little. (That information will be needed to calculate the number of stairs) If your lot lines are close, include them on this drawing so you can prevent the deck from encroaching into your local zoning setbacks. Now that you have your critical house and terrain information drawn to scale, go for it! Based upon the information you provided in the above, start drawing your dream deck! I’ll bet your next question will be «what materials do I need to get started?»

Things You’ll Need

Question: «What things do I need to get started?»

Answer: How did I know that? You will need a 100′ measuring tape, a pencil, eraser (most important tool), 1/4″ graph paper (11×17 works best), ruler (triangular engineer’s ruler with 40 scale is best), string (to help layout the deck on the ground), and optional line level and optional Polaroid camera (you’d be surprised how many trips out to the yard I’ve saved by having a photo of the back of the house).

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