The location and design of a deck should be influenced by several factors:
- Anticipated use (sunbathing, large parties, family relaxation, outdoor cooking)
- Air currents (take advantage of gentle breezes or block prevailing winds)
- Existing structure (compatible with function, environment, style)
- Sunlight (desire sun or shade?)
- Privacy (screen certain areas, avoid street noise, landscaping)
- View (emphasize a good view or mask a poor one)
- Safety (framing connections, stairs, railings)
- Access to and from the home (adjoin kitchen, den, bedroom)
- Terrain (elevated deck, ground level, split level)
- Other personal needs and preferences
Decks originally gained popularity as a way of adding outdoor living space on hillside lots. However, many decks today are built on level ground where they offer firm, dry footing close to the home. Decks can be built just inches high or elevated well above the ground. They may be free-standing or attached to the home.
It's important, of course, to site the deck so that it does not obstruct access to any utility or drainage lines. If not sure of the location or depth of buried electric, telephone, gas, water or sewer lines, contact utility providers before any digging begins.
Keep in mind the deck's intended use. Does it need to be large enough to accommodate benches, lounge chairs, perhaps a table for outdoor dining, or a grill? How many people will be using the deck at any given time? These are elements that must be considered in planning for proper size and design.
Once the basic size, shape and location of the deck are selected, check local building codes. In addition to code requirements, there may be neighborhood covenants that restrict height and/or size. A construction permit may be needed, along with a plan submission. Do not order any lumber or start work until it is certain that local requirements are met.
In addition, consider the following:
Layout: Mark off the deck area using string and “batterboards” making sure that it is level and square (see Figure 1). The string will help you visualize the size and appearance of the finished deck and serve as a guide for excavation and post placement.
Squaring: (1) Attach string to house and/or batterboards (see Figure 1). Make sure the string is level. (2) Use a felt tip marker to mark string 3 feet from corner in one direction and 4 feet from corner in the other direction. (3) Move the string attached to the batter board to the left or right until the diagonal connecting the two marks measure 5 feet. You have a right triangle and the angle at the corner will be 90 degrees. (4) Check the accuracy of the layout by comparing the diagonal measurements corner to corner. They should be the same.
Ground Level Decks: Site preparation is very important for ground-level decks. Prepare an area approximately 2 feet larger than the footprint of the deck site. Remove sod to a depth of 2 or 3 inches and replace with fill (clay, sand, gravel) to prevent water from ponding beneath the deck. Be sure the ground is sloped to direct runoff away from the deck and home. To prevent weeds and unwanted vegetation from growing up through the deck, spread polyethylene sheeting over the area. Secure the sheeting around the edges with gravel, pebbles, bark chips or other decorative edging.
Elevated Decks: Useable space under elevated decks may be converted to dry areas for additional recreation or storage. Web search on key words “deck drainage systems” for options.
Use Right Treatment: Make sure the wood is treated for its intended exposure. Check plastic end tags or stamps affixed to the lumber for “above ground” or “ground contact.” Do not use lumber marked “above ground” for “ground contact” applications.
Best Face Forward: Before you begin assembly, lay out your lumber with the best looking face exposed. Decide which pieces you want for visible areas, such as the band joist or bracing, and which pieces for understructure, such as joists. Decking should be installed bark side up. See Decking & Stair Treads.
No Landscape Timbers: Do not use landscape timbers for deck posts, railings, fence posts or other structural lumber. Landscape timbers are decorative items only and are not manufactured, graded or treated for structural use.
Spans: Do not exceed maximum spans for structural deck components, such as joists and beams. Consult maximum span tables in the Prescriptive Residential Wood Deck Construction Guide.
Access: Pressure-treated lumber ramps can provide economical, safe and practical access to decks and porches for the disabled. The Center for Universal Design offers the publication Wood Ramp Design as a handy guide.