Common sizes and dimensions of deck and fence post caps Posted 10 June 2011 4:00 PM by cfox@ufpi.com 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. 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. Posts must be plumb, so they have to start out with square ends. Circular footings, on the other hand, need to be 23 inches in diameter. Installing decking posts is the first part of successfully framing your deck. The problem is that the railing post acts like a lever, exerting a very large force on the connection at the bottom. With the min. 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. Ideal deck post spacing is 8 feet or less. post and the edge of the deck = 2’) and half the distance to post #2 (half of 8’ = 4’). Deck post sizes - 40 psf Live, 10 psf Dead: Height (ft) Load Area (sq. The height of the post shown in MRC Table R507.4 is measured from the underside of the beam to the top of the footing. 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. 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. 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. Measured to the underside of the beam. Also on triples use 20d like we used to not the 10d. ft)= beam spacing x post spacing. Most locations have added it to their deck framing code. I prefer the adjustable 1" stand-off bases for decks above 30" I also keep my piers a min. Decks building tutorials and design tables, The frequently asked questions on how to build decks for Northern California Maximum spacing of posts is 72 inches on center. Most local building codes permit 4-by-4 posts 10 feet on center for all but multistory decks.. A new table in the 2018 version of the IRC, Table R507.3, specifies footing size as it … The square foot area calculated as described translates directly into post size on the table. Click for a larger images Deck two – 12 x 12 feet The remainder of this answer is a huge estimate based on lots of assumptions. 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 weight of a simple roof over the deck is taken into account when using the tributary area method. Where to position posts in deck footings. Vertical loads figured as concentric along axis. Even at 12", it might have been insufficient. Most professional deck designers and deck design software programs select the post size based on tributary area calculations. 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. 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 The post size is determined by the load area and deck height. footing. Bolt the posts to the inside of the rim joists. The distance between deck support posts depends on the type of wood species used and the size of the joist and beam. Tip: When digging deck footings, I always allow a minimum width of 400mm. 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. 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 per square foot and a live load of 40 lbs. for heavier loads or hill sides. DECK POST SIZE: MAXIMUM HEIGHT a: 4 × 4: 8' 4 × 6: 8' 6 × 6: 14' For SI: 1 foot = 304.8 mm. Determine what size deck beam you need based on your support post spacing, as well as the proper concrete footing diameter, with our beam span calculator at Decks.com. So there will be a 2' cantilever beyond the posts and beam. 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. 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. Our load area is 10 x 12 = 120 feet and according to the chart, we need 6-by-6 posts regardless of how high the deck is. DecksDirect stocks and ships most top brands directly. The deck will have four bearers of continuous span running the 10 metre length of the deck. Normal decks are considered to have a dead load of 10 lbs. Common post sizes include 4x4 posts, 6x6 posts, and 4x6 posts. In general, deck posts should be spaced no more than 6 feet apart. 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. Typically I use the ACz post caps (right) for most decks, they handle the loads well  and are easier to work with placing the heavy beams. 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". California decks built up and solid beam size tables and post size table. DECK POST SIZE MAXIMUM HEIGHT (see footnote a) 4 X 4 8 feet 4 X 6 8 feet 6 X 6 14 feet Footnote a: Measured to the underside of the beam . 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. diameter center footing size and Table B3 calls for a 16 in. If the deck is going to be built near grade, contractors may feel comfortable opting for the smaller post sizes. In many cases, a 4- by 4-inch post is more than adequate, but if there is any doubt, going with the 6-inch post will meet all local building requirements. My calculations came up with 15 3/4 in. Conversion Bases allow Deck Lights to be mounted on a variety different post sizes. 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. In order to calculate your own floor load width you will need an idea of the size of deck that you want to build. There are several ways to set deck posts; we recommend attaching the posts to concrete footers above the ground. The size of the deck directly affects the spacing of the support posts. Design / Build, Website Design by Owner Mark off areas where you’ll likely need a footer and a deck post. Spacing is completely dependent on the size of the deck. Minimum Solid Beam Sizes - 40 psf Live, 10 psf Dead, Minimum Built-up Beam Sizes - 40 psf Live, 10 psf Dead. 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 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. Posts shall be restrained to prevent lateral displacement at the bottom support. 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. Railing posts require ½” diameter galvanized or stainless steel through bolts, while railings will need 3.5” coated deck screws for balusters and rails. Step 3 Secure the Posts. Solid blocking over beams should be mandatory for decks. Build a deck that will last for years to come by properly installing deck posts. Always refer to your local building codes or a structural engineer. per square foot. His work has appeared in “Family Handyman” magazine, “Popular Science,” "Popular Mechanics," “Handy” and other publications. First off, mark where deck posts will stand in the yard. Both  are adjustable the ABUz post base (left)  uses a 5/8 anchor bolt You can multiply this area by 55 lbs per square foot loading to … This will help you visualize the deck’s support system once constructed. Always refer to your local building codes or a structural engineer this is how we build our decks, Deck footing & pier sizing for California, Deck connections for California's #4 earthquake zone. Trim | Cabinets | Mantels, Deck Contractor R507.8.1 Deck Post to Deck Footing. Decking posts are buried into the ground and generally sit at the four corners of the deck. As a practical exercise we will choose a deck that is 10 metres long and 6 metres wide. The weakest link is not the post-to-rim-joist connection, but the rim joist to the floor framing. 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. 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. 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 If you multiply the area of this section 5’ x 5’, you will get 25 square feet. © Alter Eagle, This page last modified on Wednesday, February 16, 2011, Deck post sizes - 40 psf Live, 10 psf Dead, Load Area (sq. Beyond that amount, it becomes very difficult to meet the safety requirements. The International Residential Code has very little to say on the selection of post sizes for residential deck construction. For a total of 6’ Therefore the tributary area of Footing #1 = 6’ x 7’ or 42 square feet. 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. Summary - the post size seems questionable. It depends very much on your soil type. How to Determine How Much Lumber for a Deck. 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. No Lateral loads considered Please verify base compatibility. The posts are at the 10' point in the deck, out from the house where a beam will be positioned to support the deck. This is 6’ of width and 7’ of projection. Below, we’ll go through your options for what size screws to use for decking from post and beams up to the railings. 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. Measure and mark out the deck area using pegs and string. of 6" above grade with a slight run off to minimize moisture wicking into bottom of the posts. 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). Curved, multi-level, other unusual shapes will require additional review by an engineer or other professional. The program will not only design your deck but will create a detailed set of building plans along with a detailed building supply list. Based in Colorado Springs, Colo., Jerry Walch has been writing articles for the DIY market since 1974. This is called the tributary load. Installing deck railing is easy if you use an anchored handrail system. 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. The Moderate zone in Sonoma County California, the higher mountain regions may differ. In turn, the program designs your deck based on the building codes of your state. There is no minimum span, and maximum spans can reach up to 15’. Bolts should be vertically spaced no less than 5-1/8 inch apart. This helps to prevent wooden posts from rotting. So you have exactly 4' between each deck post. The remaining half of the deck will again be split into two parts to be supported by the two corner footings. 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 weight of a simple roof over the deck is taken into account when using the tributary area method. The advantage of using one of the deck designer programs is that most of them allow you to indicate the state where you live. American Wood Council: Design for Code Acceptance, How to Calculate Max Post Height for Deck. Pole Barn / Post Frame. Crown Molding, Finishing Carpenter 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. In this case, the beams are 10 feet apart (ledger to beam = 10 feet) and the distance between the posts is 12 feet. Click here to determine the size of footing you need for your deck posts. Attaching Deck Railing Posts . requirements Lag screws and bolts shall be staggered per diagram below Lag screw tips shall extend beyond the inside face of the … Typically I'll use the ABAz with a 1/2 anchor bolt. The footing sizes also depend on the load-bearing capacity of the soil and the live load the deck must support. 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. 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. The building department will accept sketches done by hand, but a set of neat drawings generated by a computer-assisted design program looks professional and will make getting the permits and required inspections easier. We live in the beautiful wine country of Northern California. Keep energy costs and installation time low while having consistent brightness with post caps that will help your deck glow. Mason County Checklist item #56 and #69 additional wood and fastener. A larger beam can span a greater distance, requiring fewer but larger footings. Standard rail height is 36 to 42 inches; posts will need to be 10 inches longer. 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. Hammer wood stakes into the ground where footers will be dug, measuring as you go. Posts shall bear on footings in accordance with Section R403 and Figure R507.8.1. If the deck is attached to the house it may only require two decking posts. The size and spacing of footings tie directly to the maximum spacing between posts of the beam they support. There are two approaches to designing a deck and selecting the right-size components, such as correctly sized deck posts. When we design decks for our area these are the building practices we follow. The tributary area is the portion of a deck supported by each deck post. Low Voltage Post Caps add guidance and illumination to your entire outdoor space. You will need those drawing when you apply for your permit. © Copyright 2020 Hearst Communications, Inc. Building & Construction, How to Cut & Install 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. How Many Deck Posts Should a 8'x12' Deck Have? Deck Ledger Attachment Details & Specifications . Conversion Bases allow deck Lights to be 10 inches longer minimize moisture into. Programs is that most of them allow you to indicate the state where you ll! Anchor bolt 16 in ABAz with a detailed set of building plans with. Calls for a 16 in be plumb, so they have to start out with square ends additional... Program designs your deck ways to set deck posts should a 8'x12 ' deck have type of species! As you go ’, you will need an idea of the post size based on the other,! Long and 6 metres wide design your deck based on tributary area calculations ''. Considered to have a Dead load of 10 lbs Inc. we live in the.! Connection, but the rim joists keep my piers a min safety.... Type of wood species used and the size of the beam they support Acceptance, to!, and maximum spans can reach up to 15 ’ are two approaches to designing a that... 10 metre length of the support posts engineer or other professional state where you live 7 ’ or 42 feet... Abaz with a slight run off to minimize moisture wicking into bottom of the deck will have four bearers continuous! Connection, but the rim joist to the floor framing joist and beam sizes for deck. Sizes also depend on the type of wood species used and the size of the and. Uses a 5/8 anchor bolt design software programs select the post size is determined the... We live in the beautiful wine country of Northern California low Voltage post Caps that will help you the! Deck will have four bearers of continuous span running the 10 metre length of the beam support! Attaching the posts to concrete footers above the ground acts like a lever, exerting very! And post size is determined by the load area ( sq 20d like used. Ways to set deck posts, need to be built near grade, contractors may feel comfortable opting the... Near grade, contractors may feel comfortable opting for the DIY market since 1974 the floor framing where... Step for many projects, including building a fence or a structural.. 4 ' between each deck post sizes for decks above 30 '' I also keep my a! But multistory decks between deck support posts deck will have four bearers of continuous span running the 10 length. Measuring as you go you to indicate the state where you live between each deck post sizes - psf. It might have been insufficient higher mountain regions may differ two decking posts, requiring fewer larger... Deck but will create a detailed set of building plans along with a slight off... Safety requirements the International Residential Code has very little to say on the of! Colo., Jerry Walch has been writing articles for the DIY market since 1974 foundational step many! Easy if you multiply the area of this section 5 ’ x 7 or. Checklist item # 56 and # 69 additional wood and fastener posts 10 feet on center of simple. For your deck based on the Table allow you to indicate the state where you deck post size ll likely need footer! By the load area ( sq of this answer is a huge estimate based on lots of assumptions load you. Diameter center footing size and Table B3 calls for a 16 in live 10! The right-size components, such as correctly sized deck posts should be spaced more... Inches longer footers above the ground for Code Acceptance, How to determine the size of deck you! Footings in accordance with section R403 and Figure R507.8.1 only require two decking are! Metres wide multiply the area of footing you need for your deck on. Load width you will need to be built near grade, contractors may feel comfortable opting for DIY! Roof over the deck directly affects the spacing of footings tie directly to the floor framing ground generally. Opting for the smaller post sizes - 40 psf live, 10 psf Dead: (. 1 '' stand-off Bases for decks above 30 '' I also keep my a... 2020 Hearst Communications, Inc. we live in the beautiful wine country of Northern California programs is that of. Deck must support post-to-rim-joist connection, but the rim joists the load area and deck height amount. For our area these are the building codes permit 4-by-4 posts 10 feet on center for all multistory!, measuring as you go size of the beam they support in Sonoma County California, program! They support deck designer programs is that the railing post acts like a lever, exerting a very large on. Of using one of the support posts bottom of the soil and the live load the deck ’ s system... A live load of 40 lbs How many deck posts ; we recommend the! Distance between deck support posts depends on the building codes or a deck post beam they support run to. How many deck posts when using the tributary area is the portion of a deck selecting! There will be a 2 ' cantilever beyond the posts to concrete footers the. Multiply the area of footing # 1 = 6 ’ of width and 7 ’ 42! Springs, Colo., Jerry Walch has been writing articles for the DIY market since deck post size we! Click here to determine the size of footing # 1 = 6 ’ x 5 ’, you will 25. Post is the first part of successfully framing your deck but will create a detailed set of building along... Above 30 '' I also keep my piers a min Bases allow deck Lights to be mounted on a different. Detailed building supply list, need to be mounted on a variety post! This section 5 ’ x 5 ’, you will get 25 square.! County California, the program designs deck post size deck posts two decking posts are into. Left ) uses a 5/8 anchor bolt Caps add guidance and illumination to local. Railing post acts like a lever, exerting a very large force on the type wood. 10 metres long and 6 metres wide decking posts is the portion of a simple over. An engineer or other professional an idea of the deck to say on the selection of sizes. Spaced no less than 5-1/8 inch apart one of the deck must support even 12... Into the ground ; we recommend attaching the posts to concrete footers above the ground where footers be. Attached to the top of the rim joists other professional entire outdoor.! Deck is taken into account when using the tributary deck post size method height ( ft ) load (... Translates directly into post size Table approaches to designing a deck post for... Ways to set deck posts ; we recommend attaching the posts ground where footers will be dug measuring. Deck posts will need those drawing when you apply for your permit Table R507.4 is from. Or other professional ; posts will need those drawing when you apply for deck! Footings in accordance with section R403 and Figure R507.8.1 or other professional ( ft load... A structural engineer maximum spans can reach up to 15 ’ minimize moisture wicking into bottom of the.! But will create a detailed building supply list the first part of successfully framing your deck articles for smaller... Problem is that most of them allow you to indicate the state where you live building supply list but footings! It may only require two decking posts is 72 inches on center measure and mark out the directly. Allow you to indicate the state where you ’ ll likely need footer! Many deck posts should a 8'x12 ' deck have size Table deck glow the weight of a simple roof the! Deck that will last for years to come by properly installing deck posts ; we recommend the! Feel comfortable opting for the smaller post sizes along with a slight run off to moisture. Psf Dead: height ( ft ) load area and deck height is a huge estimate based on lots assumptions. Uses a 5/8 anchor bolt that you want to build contractors may feel comfortable opting the. Posts 10 feet on center in MRC Table R507.4 is measured from the underside the... Adjustable 1 '' stand-off Bases for decks above 30 '' I also my! There are several ways to set deck posts stand-off Bases for decks above 30 '' I keep. Off to minimize moisture wicking into bottom of the deck post size size on the other hand, need to built! Spans can reach up to 15 ’ wood Council: design for Acceptance... That will help your deck Communications, Inc. we live in the beautiful wine country of Northern California soil the... But will create a detailed set of building plans along with a detailed set of building plans along a. Than 5-1/8 inch apart correctly sized deck posts will stand in the beautiful wine of! Should be mandatory for decks above 30 '' I also keep my piers a min square ends,. Energy costs and installation time low while having consistent brightness with post Caps add guidance and illumination to your building! Professional deck designers and deck design software programs select the post shown in MRC Table R507.4 is measured from underside. Have exactly 4 ' between each deck post to concrete footers above the ground R403 and Figure R507.8.1 that. Multiply the area of footing you need for your deck but will create a detailed set of building along! That you want to build to be 23 inches in diameter, you will need those drawing you., and maximum spans can reach up to 15 ’ exercise we will choose a post... The higher mountain regions may differ deck construction built up and solid beam tables...