We live in the beautiful wine country of Northern California. Common post sizes include 4x4 posts, 6x6 posts, and 4x6 posts. Maximum spacing of posts is 72 inches on center. The deck will have four bearers of continuous span running the 10 metre length of the deck. My calculations came up with 15 3/4 in. When we design decks for our area these are the building practices we follow. One of the key design factors is knowing how to calculate the post size that you will need to use to support the weight of your deck and the weight of the roof covering the deck. The two outside posts are positioned at the outside perimeter of the deck and the 2 interior posts are positioned at the 4' and 8' positions respectively. How Many Deck Posts Should a 8'x12' Deck Have? Please verify base compatibility. Bolt the posts to the inside of the rim joists. 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 Railing posts require ½” diameter galvanized or stainless steel through bolts, while railings will need 3.5” coated deck screws for balusters and rails. The Moderate zone in Sonoma County California, the higher mountain regions may differ. Keep energy costs and installation time low while having consistent brightness with post caps that will help your deck glow. There is an additional advantage to using a design program to calculate the sizes of the structural materials for your deck: They produce a detailed set of construction drawings. The advantage of using one of the deck designer programs is that most of them allow you to indicate the state where you live. Most locations have added it to their deck framing code. Mason County Checklist item #56 and #69 additional wood and fastener. Summary - the post size seems questionable. Wood posts: • 4 ft. x 4 ft. for deck heights up to 5 feet on minimum 8 inch sono tubes • 6 ft. x 6 ft. for deck heights above 5 feet on minimum 10 inch sono tubes If the deck is attached to the house it may only require two decking posts. ft)= beam spacing x post spacing : 48: 72: 96: 120: 144: up to 6: 4x4: 4x4: 6x6: 6x6: 6x6: up to 8: 6x6: 6x6: 6x6: 6x6: 6x6: Vertical loads figured as concentric along axis. To use this calculation, you need a copy of the tables found in the book "Wood Decks: Materials, Construction and Finishing," published by the Forest Products Society in 1996. In this case, the beams are 10 feet apart (ledger to beam = 10 feet) and the distance between the posts is 12 feet. The footing sizes also depend on the load-bearing capacity of the soil and the live load the deck must support. Building & Construction, How to Cut & Install As a general rule, footers are spaced 4-8 feet apart but this can vary depending on the size of your deck and strength of the footers, so do your homework. In order to calculate your own floor load width you will need an idea of the size of deck that you want to build. Even though you still have a lot of work to do after you set the posts, getting them up can make you feel like you're halfway there. Circular footings, on the other hand, need to be 23 inches in diameter. Bolts should be vertically spaced no less than 5-1/8 inch apart. Conversion bases are available to fit the following Post sizes: 3" ~ 3 1/2" ~ 4" ~ 4 3/8" ~ 4 1/2" ~ 5" ~ 6" ~ 6 1/2". Installing deck railing is easy if you use an anchored handrail system. As a practical exercise we will choose a deck that is 10 metres long and 6 metres wide. You can multiply this area by 55 lbs per square foot loading to … The post size is determined by the load area and deck height. If the deck is going to be built near grade, contractors may feel comfortable opting for the smaller post sizes. Constructing a deck may seem like a straightforward project at first glance, but a lot of structural engineering goes into designing and building a sturdy deck. DECK POST SIZE: MAXIMUM HEIGHT a: 4 × 4: 8' 4 × 6: 8' 6 × 6: 14' For SI: 1 foot = 304.8 mm. Decking posts are buried into the ground and generally sit at the four corners of the deck. Deck posts Deck post sizing requirements are in MRC Table R507.4 and are limited to single-level wood-framed decks when sizing the decks other structural components with MRC Table R507.5. Most local building codes permit 4-by-4 posts 10 feet on center for all but multistory decks.. In turn, the program designs your deck based on the building codes of your state. Deck Ledger Attachment Details & Specifications . Deck post sizes - 40 psf Live, 10 psf Dead: Height (ft) Load Area (sq. Always refer to your local building codes or a structural engineer. Design / Build, Website Design by Owner Posts must be plumb, so they have to start out with square ends. California decks built up and solid beam size tables and post size table. R507.8.1 Deck Post to Deck Footing. After you found the true measurement of your post width, finding your perfect post cap opening size for your deck or fence post is a breeze.The ideal fence or deck post opening size is between 1/16 to 1/8 of an inch larger than the width of your post. His work has appeared in “Family Handyman” magazine, “Popular Science,” "Popular Mechanics," “Handy” and other publications. Setting the posts for your deck requires careful work, but it can also be exciting because the posts are the first visible sign that your deck is going up. A larger beam can span a greater distance, requiring fewer but larger footings. The remainder of this answer is a huge estimate based on lots of assumptions. Minimum Solid Beam Sizes - 40 psf Live, 10 psf Dead, Minimum Built-up Beam Sizes - 40 psf Live, 10 psf Dead. Deck two – 12 x 12 feet In general, deck posts should be spaced no more than 6 feet apart. Below, we’ll go through your options for what size screws to use for decking from post and beams up to the railings. It depends very much on your soil type. A new table in the 2018 version of the IRC, Table R507.3, specifies footing size as it … per square foot and a live load of 40 lbs. for heavier loads or hill sides. With the min. The data you enter provides a guideline for square or rectangular deck with no substantial items on the deck itself (such as a hot tub or outdoor kitchen, etc). The weight of a simple roof over the deck is taken into account when using the tributary area method. Posts shall bear on footings in accordance with Section R403 and Figure R507.8.1. © Alter Eagle, This page last modified on Wednesday, February 16, 2011, Deck post sizes - 40 psf Live, 10 psf Dead, Load Area (sq. Solid blocking over beams should be mandatory for decks. No Lateral loads considered DecksDirect stocks and ships most top brands directly. If you multiply the area of this section 5’ x 5’, you will get 25 square feet. The program will not only design your deck but will create a detailed set of building plans along with a detailed building supply list. This will help you visualize the deck’s support system once constructed. Spacing is completely dependent on the size of the deck. I prefer the adjustable 1" stand-off bases for decks above 30" I also keep my piers a min. Based in Colorado Springs, Colo., Jerry Walch has been writing articles for the DIY market since 1974. A comparison of the footing sizes I calculated for the example deck resting on 1500 psf soil in the Sizing Deck Footings article and DCA 6 Table B3 shows an almost identical result. In simple terms, the tributary area is equal half the length of the beam on each side of the post multiplied by half the joist length to the next support plus the full length of the joist cantilevered past the support beam. of 6" above grade with a slight run off to minimize moisture wicking into bottom of the posts. So you have exactly 4' between each deck post. Trim | Cabinets | Mantels, Deck Contractor Common sizes and dimensions of deck and fence post caps Posted 10 June 2011 4:00 PM by [email protected] Deckorators ® , the industry leader in post caps / post tops for decks and fences, offers many post caps in various shapes and sizes, but the most common sizes are 4x4 and 6x6, which are made to fit a standard 4x4 or 6x6 pressure treated lumber or cedar post. There are several ways to set deck posts; we recommend attaching the posts to concrete footers above the ground. Decks that are going to be built higher than just a few feet off the ground will likely need something more substantial than a simple 4×4. The tributary area is the portion of a deck supported by each deck post. Pole Barn / Post Frame. Most professional deck designers and deck design software programs select the post size based on tributary area calculations. This helps to prevent wooden posts from rotting. This is 6’ of width and 7’ of projection. So there will be a 2' cantilever beyond the posts and beam. American Wood Council: Design for Code Acceptance, How to Calculate Max Post Height for Deck. If you have to use a built-up I suggest placing a flashing cap or membrane that won't break down and not use the ardox (threaded nail) as prescribed but use sds screws or thru-bolts. While a 16-foot-by-16-foot backyard deck for recreational purposes, such as an outdoor kitchen and general lounging, may only require deck posts spaced every 7 feet, a larger deck may require that the spacing be narrowed down to within 5 feet. For a total of 6’ Therefore the tributary area of Footing #1 = 6’ x 7’ or 42 square feet. The problem is that the railing post acts like a lever, exerting a very large force on the connection at the bottom. Redwood 4x4: 10: 10: 9: 8: 7: 7: 6: 6: 5: 4: 6x6: 12: 12: 12: 12: 12: 12: 12: Hemlock: 4x4: 10: 10: 10: 9: 8: 8: 8: 7: 7: 6: 6x6: 12: 12: 12: 12: 12: 12: 12: 12: 12: 12: Douglas Fir, Pine: 4x4: 10: 10: 10: 10: 9: 9: 9: 8: 8: 7: 6x6: 12: 12: 12: 12: 12: 12: 12: 12: 12: 12 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. Typically I'll use the ABAz with a 1/2 anchor bolt. Walch spent 40 years working in the electrical trades and holds an Associate of Applied Science in applied electrical engineering technology from Alvin Junior College. Click for a larger images I put the built-up beam span table below but I would very rarely use a built-up beam in an exterior application where they are exposed to the moisture conditions like a deck. Click here to determine the size of footing you need for your deck posts. Crown Molding, Finishing Carpenter Beyond that amount, it becomes very difficult to meet the safety requirements. That portion of the International Residential Code is based on the National Design Specifications for Wood, which indicates that a 6- by 6-inch post is adequate for all but the most extreme residential deck. There is no minimum span, and maximum spans can reach up to 15’. Mark off areas where you’ll likely need a footer and a deck post. Build a deck that will last for years to come by properly installing deck posts. Measured to the underside of the beam. As a general rule, if the support posts are spaced no more than 10 feet on center, all you will need to use are 4- by 4-inch posts. Curved, multi-level, other unusual shapes will require additional review by an engineer or other professional. The remaining half of the deck will again be split into two parts to be supported by the two corner footings. Hammer wood stakes into the ground where footers will be dug, measuring as you go. Normal decks are considered to have a dead load of 10 lbs. Two reasons; first, it’s easier to dig; second, the wider deck footing provides enough room for me to move the post around in the deck footing while maintaining the minimum 100mm clearance around the deck post. Load Area (sf) per Deck Post; Maximum Deck Post Height (ft) Wood Species: Size sqft: 36: 48: 60: 72: 84: 96: 108: 120: 132: 144: W. cedar. You can design your deck using one of the many free online deck designer programs, or you can make all the calculations yourself using pen and paper. Also on triples use 20d like we used to not the 10d. © Copyright 2020 Hearst Communications, Inc. Both  are adjustable the ABUz post base (left)  uses a 5/8 anchor bolt Vertical loads figured as concentric along axis. There are two approaches to designing a deck and selecting the right-size components, such as correctly sized deck posts. Setting a post is the foundational step for many projects, including building a fence or a deck. These are the beam size tables I use from the UBC code I find they still work well, I laid them out so they are easier to read and I found them better than the interior IRC table or the new deck prescriptive. Step 3 Secure the Posts. This is called the tributary load. Ideal deck post spacing is 8 feet or less. 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