Whether you’re new to deck building or an experienced pro, best practices help make the job go faster and better. Use tools and fasteners specifically made for treated lumber — such as the DeckForce exterior wood screws from Grip-Rite.
If you’re building a raised deck, check with your local codes to find out about permits and inspections. Also remember to call 811 to have underground utility lines marked before you start digging holes. Contact Deck Builders Franklin TN for professional help.
A beam is a structural member that carries horizontal forces perpendicular to its longitudinal direction (think balancing beam in gymnastics). Beams transfer loads from the floor, or deck, up through columns and walls to foundations. Beams can be made of wood or metal. They may also be a part of a truss, or stand on their own as a single-span bridge or walkway.
Beams are a crucial part of any structure. They create a safe load path from joists and trusses to the ground and help distribute weight evenly. They are important to make sure your deck is sturdy and safe for you and your friends to enjoy!
Typically, wood beams are cut to specific lengths to provide the strength and support for your deck. Builders use official tables from the International Residential Code, or IRC, to determine how big a beam needs to be for different types of structures and locations. Using the right size beam is essential, as a weak or undersized one can cause sagging, cracking and other damage.
The length or span of a beam determines how much weight it can carry. The larger the span, the more weight it can hold. The distance between posts is another factor in choosing the right beam. Taller decks or those built over a slope require extra bracing to keep the beams from sagging.
There are several types of deck beam construction, including flush, post and beam and cantilever. Each method has its own pros and cons, but the choice of which method to use depends on the specifics of the deck itself. A flush deck has the look of a traditional wood deck, but requires extra support in high-load areas like hot tubs or outdoor kitchens.
Post and beam is a simpler, budget-friendly method of building a deck. It can be used on a flat or raised deck and works well with stairs. It’s important to make sure you’re putting enough pressure on the joists, and a good way to do that is by installing blocking every 16″ on center in a zigzag pattern. This ensures that the joists are supporting the beams properly, and prevents them from sagging over time.
Joists
Joists are the wooden beams that support floors and ceilings in buildings. They are critical to the stability and strength of floor systems, and a vital component of roof construction. They are often confused with rafters, however, the difference between these two framing components is significant in terms of building practices and design. Understanding these differences will help home and commercial builders, remodelers, and architects make better decisions about floor and roof designs.
Floor joists are usually made of wood, with a rectangular or square cross section for strength and rigidity. They are joined together with either tenoning (a joint where one end of the joist is cut away, leaving a notch for the other joist to fit into) or by gluing and nailing. The dimensions and spacing of a floor joist depend on its intended span, load, and the deck’s surface pattern. Joists with wider spans and heavier loads require a deeper joist depth to limit stress and deflection. Lateral support called dwang, blocking, or strutting is often installed between the joists to reduce deflection and add stability.
Rafters are the sloped structural members that form a pitched roof. They are attached to wall plates and ridge beams, distributing the roof deck and materials evenly across the surface. Rafters can be built on-site, but this requires a high degree of accuracy and precision to ensure accurate notching and fitting between the components. Prefabricated rafters simplify the installation process while maintaining strength and durability.
When installing a ledger for a deck, you must first determine the joist spacing and thickness required to support your finished deck. A common recommendation is to install a 2 x 6 ledger about 18″ from the ground and attach it to the joists with 1/2″ lag screws. After establishing the ledger position, run taut strings between the batterboards to establish the perimeter of your deck and square it by adjusting the ledger-to-batterboard measurements until they are equal.
Once the deck is squared, mark joist locations on both the ledger and the batterboards with an arrow. To prepare the joists, remove any excess material from the ends and sides. Next, sand and smooth the edges of the joists to reduce any sharp corners or cuts. If necessary, splice two joists together using approved splicing methods. Finally, install blocking between the joists to prevent them from shifting or twisting over time.
Footings
Deck footings provide the foundation for a safe and sturdy structure. Without them, a deck could become unstable or even collapse over time. The footings support the weight of the posts, beams, and joists that make up the deck’s framework. They also help distribute the load, reducing pressure on each post. Footings are made from a variety of materials and methods, each with its own advantages.
Poured concrete footings are a common choice. They involve digging a hole of the proper size and then filling it with concrete. This method is relatively labor-intensive, though it may be more cost-effective than other options. Precast cement blocks offer an alternative to poured concrete footings. These pre-made blocks can be stacked together to form a strong, stable base. They come in a variety of sizes and can be used to support a variety of deck structures.
Other types of deck footings include pier blocks and metal screw piles. These are less expensive than poured concrete, but they may not be as strong. They also lack the versatility of poured concrete footings.
The type of footing you choose depends on your deck’s size, weight, and soil conditions. A larger, heavier deck may require a deeper footing to prevent shifting and sinking over time. If the deck is located in a frost-prone area, it’s important to ensure that the footing extends below the frost line.
Whether you opt for poured concrete, precast concrete, or pier blocks, the footings must be properly installed to prevent damage and maintain structural integrity. They should be firmly secured to the ground with anchor bolts, and they should be inspected regularly for signs of movement or instability. Water management is another essential aspect of footing construction. A proper drainage system helps avoid moisture damage and keeps the surrounding soil dry.
While building a deck requires heavy machinery and tough work, it also demands careful planning and fine attention to detail. By choosing the right materials and following local codes and inspection requirements, you can ensure that your new deck is safe to use for years to come.
Support Posts
Posts (or columns – the same thing structurally) are vertical bearing elements that carry the compression of the deck’s structure and transfer it to the ground. Think of a swimming noodle set vertically and under pressure – it will compress slightly then bend or deflect, and the load is transferred to the water below. That’s the same principle that applies to posts and beams.
Post size and spacing is determined by the design of a deck and the weight of its occupants and structures. Typically, 4×4 and 6×6 post are used in wood-framed decks. The bigger 6×6 posts are preferred because they allow for a greater amount of load to be carried without excessive bending. Using these larger posts requires digging holes and pouring concrete footings which can be laborious.
If a home has a wood-framed deck with a lot of heavy structures on it, additional bracing may be required to prevent the joists from twisting and moving over time. Typically, this is done by installing blocks between the joists to spread the load and reduce the chance of damage to the joists from the weight being carried on them.
Some people also use metal deck framing systems. The main benefit of this is that it’s noncombustible and can help to reduce the risk of fire in a home. The downside is that it can be more expensive than wooden framing and may require special tools to install.
Occasionally, home inspectors encounter support posts that are rated for temporary use only and not intended as part of the permanent structure of the deck. These usually come in two or more pieces where the smaller piece fits within the larger one and is secured by a metal dowel. Finding these temporary-rated posts in a home inspection is a red flag that the existing structure was not rebuilt or repaired by a professional and should be addressed.
When a home’s support posts, beams or joists start to fail it can cause serious safety issues for the occupants of the home. If rot is spreading on wooden supports, or rust is forming on steel ones, it’s best to get the issue resolved as soon as possible.
