Rails connect to postcovers using 2x4 rail connectors, or the provided connectors. Maximum cantilever of a double 2X8 beam past a support post is 12” 2. When splicing a beam, the splice must meet in the middle of the notch. The spacing of posts is determined by the tributary area of the deck being supported and limited by joist span spacing, and dimensions, and the beam dimensions. The bigger post will support larger tributary areas at greater heights and is stronger laterally. for heavier loads or hill sides. They are commonly secured at or above ground level with a metal bracket to a footing, pier, or deck block, and to the beam at the other end to prevent twisting. In 2015, the IRC limited 4×4 posts to a maximum length of 8-feet. While a typical deck under 6 feet in height may only require posts set every 5 to 8 feet, the type of deck, the type of wood, the height of the deck and a variety of other factors can influence the spacing of the support posts. The style of railing or desired look may require a different post, but for most deck railings 4×4 posts work well. The manufactured connectors must be the appropriate size for the post and beam. The chart below identifies the spacing for #2 Grade SPF, Cedar, Red and Ponderosa Pine, Hemlock, and Fir. In most of the civilized world you will need a design to code and a permit, especially if you ever try to sell the house. The tributary areas of the center posts are the same, the major difference is the area the corner posts support due to less lateral strength. Alternative approved fasteners are also acceptable. For my money, I’ll use a 6×6. Hit + and - buttons to open or close spacing, re-calculating the deck to find how different spacing options effect cost and materials. Maximum post spacing: 6' for 36" 4x4 posts; 4' for 42" 4x4 posts; 8' for 36" 6x6 posts; 6' for 42" 6x6 posts. See Engineering Reports for horizontal, compression and tension loads. Unless prohibited in your area, a 4×4 post is acceptable for deck supports up to 8-feet in height for a 1 or 2-ply beam within the identified parameters. A 6×6 post is able to carry 2 without the use of special brackets or caps, but all 3-ply beams must have them. We live in the beautiful wine country of Northern California. Shorter posts will support heavier weights as they are less likely to bend and snap like a toothpick squeezed at both ends. The post should also be secured to the footing. In the event of a single truss failure, this system will result in a domino effect and the collapse of the entire roof system. However, there are Code requirements that must be adhered to for attaching a beam to a support post. The IRC sets the guidelines most locales follow. One way is to pour concrete in the post hole, set the post on the concrete and backfill with gravel. Let's make it a present that will last for generations with these top 5 tips on how to build a deck frame and substructure. Remember to follow local code for deck posts. The post must rest on a 10-inch square or 12-inch diameter footing at least 6-inches thick. Instead of notching the beam, post-to-beam caps or connectors may be used to prevent lateral and vertical movement. (18’x7’-10”). High grades or stronger wood species support greater areas for similar lengths. With the min. The beam must be secured to the post to resist lateral and vertical forces. Solid blocking over beams should be mandatory for decks. 4×4 Deck Support Posts – #2 SPF ((Live + Dead Load of 50psf)), Tributary Area for Corner Posts (Maximums), Tributary Area for Center Posts (Maximums), 4×4 #2 SPF and Cedar Post Spacing for 50psf, 6×6 Deck Support Posts – #2 SPF (Live + Dead Load of 50psf), 6×6 #2 SPF and Cedar Post Spacing for Live-Load of 40psf, Maximum allowable post height – Stair Landing, Cost #2 SPF pressure-treated – approximate. He is passionately interested in home improvement, renovation and woodworking. Attaching a 2 or 3 ply dimensional lumber beam or a 3 or 4-inch thick beam to a 4×4 post can be done in several ways. If the deck height is greater than 2-feet, diagonal bracing at the corner posts is required parallel to the beam for lateral support – this applies to 6×6 beams too. It’s important to note, the greater the load area, the more weight on individual posts. 6×6 deck posts offer a solid, stable base for most decks. So, for posts 3-feet and shorter, it’s a matter of preference, above 3-feet use 6×6. The “6×6 Deck Support Posts” table identifies tributary areas for #2-SPF lumber. Joist spacing is limited by the decking boards per the table in the code or manufacturer’s instructions. The Tributary Area multiplied by the ‘dead’ (10psf) and ‘live’ (40psf) load rating, or the design load (50psf), identifies the weight the post may support. As always, your comments and suggestions are appreciated. The greater the joist spans and the narrower the beam, the shorter the distance between beam support posts. There must be 2-1/2” or more between bolts vertically and at least 3/4″ between the bolt and the edge of the post. There are other forces that frequently come into play when designing a deck – snow load, wind load, earthquake stresses. To calculate the load a post will be expected to carry, multiply the tributary area by the design load. It also must be flush with the postface for full bearing. The dead load is commonly considered to be 10psf and the live load 40psf, resulting in the design load of 50 psf. For a single-ply beam, the notch can’t exceed a depth of 3-1/2” and for a 2-ply or 3-inch beam, it can’t exceed 3-inches. Pros and DIYers often use a 2×6 splice block on the open face of the notch to provide additional security against vertical and lateral movement of the beam, especially on posts over 5-feet. Caps and connectors are fabricated to fit 4×4 or other sized posts, so make sure to get the correct piece. Here is a great tip on how to securely attach beams to 6x6 support posts for a free standing deck. A “cantilever” is the unsupported end of a joist that extends past the last support post at the edge of your deck. A 4×4 post is actually 3-1/2”x 3-1/2”, which does impact its structural strength. Typically I'll use the ABAz with a 1/2 anchor bolt. To avoid code violations, many deck builders choose the 6×6 even if the 4×4 is acceptable. 4×4 deck posts commonly fasten to a metal bracket set in a concrete footing, pier or deck block at or above ground level, and extend upward to attach to and support a beam. The maximum height for a 6×6 support post in the IRC is 14-feet. Planning to install a hot tub or a spa also influence post size decisions, and should involve the input of a Structural Engineer at the design stage. An intermediate landing must be built if the stairs exceed a vertical height of 12’-0” but may be used to shorten smaller stringer spans. Your post footings are the foundation of your deck and just like your house, the deck is only as strong as its foundation. The old deck post-to-footing drawing, Figure R507.8.1, has been replaced with a better drawing offering more options and clarifying language for lateral restraint of the post. This is especially true for a deck with 15' high posts in a seismic area. A 4-by-10 can usually span up to 12 feet between posts. Table R507.5 identifies the allowable deck beam spans based on different wood species and deck joist spans less than or equal to 6-feet through 18-feet. If you move up to 4-by-8, you're usually allowed to span up to 10 feet between posts. 6x6 Vs 4x4 Posts - Decks and Fencing - Contractor Talk . Click for a larger images
The best Grade of lumber (Southern Pine) for the maximum spans identified support Tributary Areas of 159sq.ft. Decks building tutorials and design tables, The frequently asked questions on how to build decks for Northern California
If a deck is raised more than 6 feet above the ground, codes may require 6x6 posts. Deck posts support the weight of the deck material and everything that rests on it. Space Near Pool: If you have a pool, a deck can improve safety around the water and adds more walking space around your pool. Paint the cut ends with waterproof sealer and then cover the post top end grain with self-adhesive water-proof tape to further reduce the risk of rot too. Additionally, a 6×6 has greater strength than a 4×4 of equal length. The footings are constructed using a round cardboard tube form that is 8” in diameter (often called a sonotube, after a popular brand). We’ll also look at posts for deck stairs and deck railings. I was … However, it is advisable to always check with the local building department as some only permit 6×6 and some permit both for specified heights. Thicker beams will support more and allow for wider post spacing. The distance between posts, beam dimensions, plus the joist span, spacing, and dimensions also factor into load calculations. Crown Molding, Finishing Carpenter
The Tributary Area is determined by the joist span between supports and beam span between posts. Both are adjustable the ABUz post base (left) uses a 5/8 anchor bolt
Live-load or snow-load are other factors to consider, as are deck size and use. If your deck is slightly out of square (different widths), calculate results for both widths, and set out each end to suit. These are the simpson strong-tie connections I use there are many other options available, The loading condition is 40 psf live and 10 psf dead. Any post more than 8 feet long we use 4x6 or 6x6. Example: A 10ft x10ft deck with 10-foot joists spanning ~8-feet between supports and a 1.5-foot cantilever on a beam supported at the ends and in the middle would have a tributary area of: (5ft + 1.5ft) x 2.5ft = 16.25sqft for the end support posts and (5ft + 1.5ft) x 5 = 32.5sqft for the center support post. Intermediate rectangular landings must be built as ledger-free decks, wide enough to support stairs at least 36-inches wide, and a landing width of no less than 36-inches. Note: The 2018 IRC Table R507.3 identifies Tributary Areas of 20 to 160sq.ft. The type of wood and length of post influence how much it will support before snapping. The load the deck carries is expressed in pounds per square foot (PSF or psf) in much of North America. Eugene has been a DIY enthusiast for most of his life and loves being creative while inspiring creativity in others. Once they are tied in with the top and bottom rails and the railing cap board attached, they’ll resist twisting and bending. Hit + and - buttons to open or close spacing, re-calculating the deck to find how different spacing options effect cost and materials. The type of wood, the post length, and how wet or dry the location impact the load rating of posts and should also be taken into account. Toenailing the beam to the top of the post is one practice. Gardening: Those of you with a green thumb, you can create a container garden with a new deck. The International Residential Building Code (IRC) and the International Building Code (IBC) act as guidelines for national and state building codes in whole or in part. Making sure it is solid and structurally sound from the ground up though, is often a matter of 4×4 vs 6×6 deck post. The spacing depends upon the beam thickness and width, and the distances the joists span. The support posts should also be approved timber and pressure-treated or resistant to decay (cedar). Two section brackets may be installed before or after the beam is placed on the post, and can adjust to different beam thickness without bending. There are several methods for setting posts. On my own deck, I had to replace a 6x6 after a year, when it bowed almost 1 1/2 inches. We will also show you how to decide the number and spacing of your footings. The maximum Center Post Tributary Area based on an 18-foot joist span on a 3-ply 2×12 beam for #2 Grade SPF posts 7’-11” apart is 141sq.ft. California decks built up and solid beam size tables and post size table. Additionally, there must be at least 2” between the top bolt and the top of the beam, and 2-1/4” between the bottom of the notch and the bottom bolt. Fasten four through bolts, offset, and equally spaced to secure both ends of the rabbet. Maximum joist span of a 2X8 is 10’ – 6” at 16” o.c. DEAR RICK: The most efficient post spacing is going to depend upon the wind and snow load conditions at any particular given pole building site. Trim | Cabinets | Mantels, Deck Contractor
In general, the maximum span for a 4-by-6 beam is 6 feet between 4-by-4 posts. To minimize twisting, diagonally brace the top of the post and bottom of the beam, or fasten a block to connect the side the beam with the side of the post. The load capacity of a 3-foot #2 grade 4×4 is 17,426 pounds, and a similar 6×6 is 20,834 pounds or 16% better. Through bolts must have a washer under the head and nut. Tables for the minimum joist spans in California's moderate climate regions, How we build a closed in riser stair for decks with a skirt for solid railings, Deck stair total rise table with calculations for riser heights and number of treads, Alter Eagle
However, an 8-foot 4×4 supports 6468-pounds and 2339-pounds at 14-feet, while a 6×6 is 18032 and 10550-pounds respectively – or 64% and 78% more load capacity. I'll use the PCz post caps (left) if I have a condition on a slope with possible lateral movement or a heavy load with a large joist over a longer span. Most professionals will encourage you to consider going with a 6×6 deck post form the outset of the project. Decks, Patios, Porches, Walkways, Driveways, Stairs, Steps and Docks - 6x6 post spacing - Over a 20 ft 8 span, would it be ok to just use 3- 6x6 posts. Multiply that area by the design load of 50psf and the load on the post is 7050-pounds. Posts at the end of a beam carry less than the posts in the middle of a beam or deck, so the middle posts may need to be thicker than the end posts. Always refer to your local building codes or a structural engineer. The beam should be centered or flush to the post sides so the weight is fully supported. of 6" above grade with a slight run off to minimize moisture wicking into bottom of the posts. A 4×4 post may be used to provide support up to 14-feet. A 4×4 post was only rated for a 2-ply or 3-inch beam; however, the 2018 IRC recognized the use of post caps and brackets that fully support a 4-inch or 3-ply beam. Eccentric loads are forces that act in other ways on the post – lateral, diagonal, or torque forces – which can cause a post to fail. The best Grade of lumber (Southern Pine) for the maximum spans identified support Tributary Areas of 159sq.ft, which is why the maximum Tributary Area is 160sq.ft. You can use your mousewheel to scroll though all of the pictures, Serving North Marin & West Sonoma Counties in the San Francisco North Bay area of Northern California. Building & Construction, How to Cut & Install
However, the IRC and maximum beam and joists spans limit the Tributary Area for specific post heights regardless of wood strengths. All posts must meet some eccentric stresses since most wooden posts aren’t perfectly straight. A 1 or 2-ply beam, or equivalent, can still mount atop an 8-foot 4×4 post. Footing and post connection (RB213, RB214). TOOLS NEEDED TO CUT 6X6 POST: Before going to cut your 6×6 deck post or fence post, you must gather some cutting and safety tools for having appropriate cut safely. There must be 3/4″ or more of the stringer below the bottom bolt, and at least 2-inches of the stringer above the top bolt. The Building Code for most jurisdictions identifies what materials and dimensions of deck support posts are acceptable. A 6×6 will work as a railing post too but is over-kill unless there are other aesthetic or structural reasons for the heavier posts. Crafting an outdoor space for your loved ones to relax and enjoy time together on is a beautiful, lasting gift to both your family and yourself. Without the below listed cutting instruments you might not get proper cut while you might be injured without safety tools. Many deck builders and DIYers tend to use 6×6 support posts and so bypass any arguments or concerns. The nominal 6×6 is actually 5-1/2” x 5-1/2” and offers ample support to 3-ply dimensional lumber beams, which is why many deck builders and DIYers use them for all deck support purposes. Based on the dimensions of the landing, either 4×4 or 6×6 posts may be used. Maximum cantilever of a 2X8 is 24” at 16” o.c. 4x4's are subject to some serious bending as they dry. The post spacing every 8′, single trusses every 4′ resting upon headers is a system our engineers are not interested in risking their careers on. For example, a 2 x 12 joist placed 16” OC. The railing or guard posts must be nominally a minimum of 4×4 and fastened perpendicular to the rim joist with (2) 1/2″ through-bolts and washers. I had a landscaper add a 3′ x 3′ landing off our existing deck (that serves as the first ‘step’) so that we were able to install stairs lengthwise along the side of the existing deck so that we were able to conserve space. Some of our articles focus on the various types of accepted footings that are used by professional deck builders. 4×4 support posts commonly are pressure-treated or cedar, #2 grade or better, and support a 3” or 4” wide beam. The 2018 IRC altered the allowable height of a 4×4 post yet again. code for nailing they will still check, may warp and will shrink at the splices which allows moisture to get trapped with dirt promoting the compromise of the beams over time. Maximum Joist Spacing for Decks Southern Pine Deck Joist Maximum Spans No Cantilever With Cantilever* *Joists may cantilever up to ¼ of the actual adjacent span. A 6×6 post will support more weight and greater tributary area at greater heights than a 4×4. However, for most decks, 50psf is a safe load value. Deck beam and post sizes - How we build our decks in the California North Bay area - Sonoma and Marin County - Santa Rosa - Petaluma - Sebastopol - Novato - Bodega Bay - Rohnert Park - Healdsburg - Windsor The load includes the weight of the deck material, the ‘Dead Load’, and the weight of people, furniture, and ‘stuff’ it carries, called the ‘Live Load’. A center post carries 1/4 of four areas based on joist and beam span; so essentially, its Tributary Area is defined by the joist span multiplied by the beam span. 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