Laying out footings is usually a two-person job. For instance, joists that are placed 24 inches apart must be wider than joists placed 16 inches apart. Copyright © 2021 Trex Company, Inc. All rights reserved. If setting timber post straight into the ground you may wish to coat the timber that comes in contact with the ground with some type preservative. In that case, the required spacing of the posts will be based on the deck loading, the span of the beams, and the geometry of the deck. Menu; How-To Plans. Installing deck railing is easy if you use an anchored handrail system. For help, simply click on the beside the section you … All piles must be lifted off the bottom of the … This measure also ensures your cables will remain properly tensioned and deflect as little as possible. … deck post spacing? … Jump to Latest Follow 1 - 14 of 14 Posts. How Many Footing Do You Need For Your Deck? When building your deck frame, the maximum spacing of Deck Posts for should be no further than 8 feet apart. Baluster Count and Spacing Video ; Deck Baluster Installation Guide ; Sale & Closeout. FIGURE AM102.1(1) SUPPORT POST FOOTING For SI: 1 inch = 25.4 mm, 1 square foot = 0.0929 m 2. Wondering where to start? (For more on other aspects of framing an elevated deck, have a look at this guide.) The delayed effective date of this Rule is January 1, 2020. Post Spacing Thoughts. These posts should be no farther apart than six feet on the flat deck and no farther apart than 5 1/2 feet on stairs. Setting Posts First establish post spacing and embedment depth. For free standing decks without knee braces or diagonal bracing, lateral stability is permitted to be provided by embedding the post in accordance with Figure AM109.1 (3) and Table AM109.2. JavaScript seems to be disabled in your browser. Top of footing shall be level for full bearing support of post. Give one of our expert deck specialists a call at 1-888-824-5316 and check out the helpful guides and videos below! 29 Jul 2011. will have a 1 … Then mark out and dig the holes for the uprights. This works well for square decks, but it can get kind of dicey with irregular shapes like octagons. Remember that the dimensions on your plan are drawn in two dimensions. You now know the three lengths of the sides of a triangle. … Decks with a lot of angles may also require additional footings. Posts for raised decks should be 100 x 100mm treated pine posts, at max. Hole Diameters: Up to 250mm posts - dig 450mm diameter holes. I have a few ideas on what needs to be done but need some help with post spacing to make sure I am not building a trampoline. How Do You Install Cable Railing Around Corners. STAY CONNECTED. 3. Stainless steel railing installations must comply with applicable standards related to post height and cable spacing. Terms of use. When deck ledgers are attached to engineered wood products (structural composite lumber rimboard or laminated veneer lumber), the ledger board attachment shall be … Joist Spacing for Composite Decking You can begin to answer your own question by using our footing and beam calculator. Give one of our expert deck specialists a call at 1-888-824-5316 and check out the helpful baluster guides and videos below! the deck will only be a couple feet high. Deck builders can now refer to Section R507.6 Deck Beams and Table R507.6 Deck Beam Span Lengths to determine the size of 2-ply and 3-ply built-up beams made from 2×6 through 2×12 lumber. With a 12’ deck span, the beam may be either two … The anchor is hidden within the post unlike unsightly bulky exterior metal post brackets. Dig post … DecksDirect Pro Tip: Using the Drivable Post Anchor by OZ-Post to create a solid deck footing for your project without the hassle of concrete is a brilliant way to keep the building process moving fast. Never miss a deal. assuming stable ground. Actual experts on the phones, chat & email. STAIRS. Deck builders can now refer to Section R507.6 Deck Beams and Table R507.6 Deck Beam Span Lengths to determine the size of 2-ply and 3-ply built-up beams made from 2×6 through 2×12 lumber. NEED HELP? For decks with grip-type or side-mounted hidden fasteners for decking-to-joist connections and with any post height greater than 2.5 feet (measured from the top of the footing to the underside of the supporting beam), install 2x6 bracing to the underside of the deck joists per the requirements below. Spacing for a deck supported by typical four-by-fours will be about six feet from post to post. deck post spacing? Deck Beams and Post Spacing – How to Determine Deck Framing Lumber Sizes. Mark the center of the footing with spray paint. Deck Joist Maximum Spans. The maximum spacing of 4x4 deck posts should be 6 feet on center, while the maximum spacing of 6x6 deck posts should be … 3. I would like to build a simple deck next to a 24' round pool maybe 12x12 or 12x14. Cable Railing Post Spacing: How Far Can I Space My Post Using The Atlantis Rail Cable Railing System? Beam Span Calculator. The shorter sides—in this case, the 8-foot side—will have 4-feet of distance between deck posts. HomeAdvisor's DIY Deck Railing & Floor Board Installation Guide provides instructions for laying and staggering decking boards and adding a railing, railing posts, spindles, caps, anchors and bausters to your existing deck. Learn how much spacing should go between handrail posts and how to install boards and railing for corner decks. These values didn’t change in the 2018 version of the IRC. The larger the beam and footing size, the fewer footings that are required. If you don't want to use the "standard" sizing that the Code gives you, your option is to compute the required size for each element based on some assumed loading you determine based on knowledge of the used of your deck. Footing layout plans are available with all of our free deck plans. Their website says each post supports a load of 5000 lb each. Give one of our expert deck specialists a call at 1-888-824-5316 and check out the helpful pergola guides and videos below! Use the dimensions on the footing plan to lay out the footings in your yard. What … By clicking GO!, you acknowledge that you have read Trex's Privacy Policy. Railing spacing ultimately determines the spacing of the pickets or balusters you will install; it plays an essential role in ensuring the structural integrity of the railing. When determining the height of railing posts, individuals should factor in the type of location, as well as local, city and/or international building codes. Posts are to be 4x4's Thanks . The maximum spacing of 4x4 deck posts should be 6 feet on center, while the maximum spacing of 6x6 deck posts should be 8 feet on center. Here is a list of some common joist sizes and maximum “spans”. Of course, a 6×6 post for the deck has a few other benefits beyond just its load-bearing abilities. Guardrailing Post Specifications Requirements & codes for guardrail posts on decks & stairs ... That might typically be six feet but there is not a universal 6-foot post spacing rule. Guardrailing Post Specifications Requirements & codes for guardrail posts on decks & stairs ... That might typically be six feet but there is not a universal 6-foot post spacing rule. The future is … I'd use two rows of 4, stretching the 16 ft. How you space them is more than I'd like to describe here, other than plan the 16 ft runs as two 8' sections each. Wondering where to start? Discuss. Insulation: Attic blown fiberglass, walls R-19, Basement R-19. You can start here in order to lay out the perimeter of your deck by tying string between 1x2 wooden stakes set perpendicular to one another. Jump to Latest Follow 1 - 14 of 14 Posts. Conventional post + wood-rail & baluster guardrail construction. Customer Service. Maximum post spacing 400mm max. Some builders reduce joist spacing to 12" on center to strengthen the deck frame or to increase maximum allowable joist spans. If the footing locations appear out of line, you should double check that your tapes are level and that the stationary points match the footing layout drawing. The tributary load is the load carried by any one post in your deck. Tributary Load. assuming stable ground. Get $10 off your next purchase. Post Heights and Cable Spacing. Use a footing triangulation drawing to locate your footings based off of two known points along the house wall. You will need to work off of two fixed points along the house, the distance between which will form one side of your triangle. Use the Beam and footing sizes table and find the 8' post spacing column. Maximum spacing of posts is 72 inches on center. I would like to build a simple deck next to a 24' round pool maybe 12x12 or 12x14. I was just going to keep it simple square/rectangle with slight … If you're installing parting boards in the middle of the deck, start marking the joist spacing from the center of the beams working toward the end joists. Starting with your perimeter, mark the location of each deck post to locate the fitting position. 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. 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. WEBSITES . Posts. For most situations, you will want to place footings and posts less than 8' apart. How to Build a Deck on Sloped or Uneven Ground. For the best experience on our site, be sure to turn on Javascript in your browser. Please adjust post spacing and / or beam spacing to reduce the load on the footings. the deck will only be a couple feet high. Cut the Posts. Most backyard decks using wooden posts rely on the 5-to-8-feet average for the post spacing, but modern advancements in deck building now allow for metal posts as well as composite posts to be used in place of traditional wood. 2 grade lumber or other approved materials as determined by good engineering practices. Departments. Glass Deck Railing. Aligning 4 in a row to accept 16' beans takes some planning and luck. Search for: post spacing for deck. Bracing piles (see bracing requirements below) need to have a 350mm x 350mm wide and 450mm deep concrete footing with a diagonal brace connecting to another bracing pile. Bolts should be vertically spaced no less than 5-1/8 inch apart. Using Decks.com footing layout plans and (2) 50’ cloth tape measures, you can measure the specific dimensions from each of these endpoints to the centers of each footing. Featured Brands. Secure balusters with screws or spiral-shank nails. Never use multiple stabilizers to attempt accommodation of rail … Bolt the posts to the inside of the rim joists. Metal Railing. Wondering where to start? If you are planning on installing a hot tub or porch on top of your deck, you will usually need more footings and posts to support the additional loads. For a composite railing system, slide the post sleeve over the wood post, then … Post Anchors are made to support a maximum raililng height of 42 inches. The maximum distance between footings is determined by the size of your joist material. Sign up for our email newsletter. This process works best with two people with 50' cloth tape measures. Cut ends of posts shall … Calculators. What's New; Photos. Wondering where to start? Where it intersects with the deck joist span provides you with the maximum spacing between your posts. With Cantilever*. A span is the unsupported … The farther a deck beam must span—that is, the farther apart the posts are—the more massive a beam must be. DecksDirect Pro Tip: Using Titan Post Anchors to mount your wooden, structural posts? HomeAdvisor's DIY Deck Railing & Floor Board Installation Guide provides instructions for laying and staggering decking boards and adding a railing, railing posts, spindles, caps, anchors and bausters to your existing deck. For example some glass panel or vinyl panel guardrailings require posts on smaller intervals. Above Ground Pool Deck Post Spacing. Step 3 Secure the Posts. Some builders position them every 4 feet for a completely rigid frame. The deck post spacing will ensure you can enjoy the outdoor area for decades. Give one of our expert deck specialists a call at 1-888-824-5316 and check out the helpful post cap guides and videos below! Videos. About Us Qualifications & Websites. B ... What is the correct way to determine the spacing and number of posts needed? EBTY Hidden Deck Fastener by Simpson Strong-Tie, Aluminum Post Sleeves & Aluminum Post Covers, How to Measure Your Deck for Railing Video, Trex RainEscape vs Zip-Up UnderDeck Video, How to Install the SCREENEZE system Video. Decking; Building Supplies; STAY UP-TO-DATE. It usually helps to have the ledger board installed to give you two fixed positions at the house to work off of. You must keep your lines or tapes level in order to avoid distorting the shape of the deck in a three dimensional space. Most backyard decks using wooden posts rely on the 5-to-8-feet average for the post spacing, but modern advancements in deck building now allow for metal posts as well as composite posts to be used in place of traditional wood. Can I use 2 6x6 posts on concrete piers with 2x12's beams sandwiched around them. The other side wall posts need: Your project will need: The current design of your deck requires a footing larger than 24" diameter. Never attempt to use a cable stabilizer on rail sections over 7 feet. With a 12' deck span, the beam may be either two 2x8s or two 2x10s, depending on the wood used. Piles are the posts that get concreted into the ground and support the weight of the deck structure. Deck Framing (page 16) Beam-to-Post (page 12) Post-to-Concrete (page 11) Joist-to-Beam (page 14) A system of key connections throughout the deck framing, also known as a continuous load path, is essential to building a safe, code-compliant deck. Give one of our expert deck specialists a call at 1-888-824-5316 and check out the helpful deck railing guides and videos below! CLICK TO ENLARGE For a sturdy top rail, use long, continuous pieces of 2×6, chamfered or sloped to shed water. You will need an open space to work in, and you must move anything that will interfere with your lines or tapes in the site area. The Titan post anchor is the most advanced hidden wood post anchoring system of its kind. No Cantilever. Beams will be made from 190 x 90 (2 x '190 x 45') Treated Pine Joists will be made from 90 x 45 Treated Pine (If these need … The maximum distance between footings is … Starting with your perimeter, mark the location of each deck post to locate the fitting position. If the footing locations are square, you can prepare to dig. I am planning to build a deck 6.0m wide along the side of my house and 4.5m deep. To ensure your system performs as well as designed, be sure to space structural posts 4ft apart center-to-center. Shop Sale Balusters ; Railing Systems. For most situations, you will want to place footings and posts less than 8' apart. The Titan post anchor is the most advanced hidden wood post anchoring system of its kind. You will need a cloth tape measure, some wooden stakes and a roll of twine. What Is the Required Spacing for Deck Posts? Alter Eagle Finish Carpentry How to Install Crown Alter Eagle Decks. Posts are to be 4x4's Thanks . What is Proper Post Spacing? Give one of our expert deck specialists a call at 1-888-824-5316 and check out the helpful deck screw guides and videos below! Getting Started. Post Anchors are made to support a maximum raililng height of 42 inches. Price Match; Weekly Flyer; Returns & Refunds; Store Locator; Shipping Policy; In-Store Pick Up; Truck … My Pool. If at any point in your project you have any questions, feel free to give our deck experts a call at 1-888-824-5316 or send us an email at hello@decksdirect.com. Products are in-stock & ready when you order. 0 Items. or 2x12s at 24” O.C. 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. Enter your email address. The anchor is hidden within the post unlike unsightly bulky exterior metal post brackets. Sign Up. What Is the Required Spacing for Deck Posts? All deck support posts shall be a minimum 6”x6” with a maximum unsupported height of 10’-0” measured from the top of the footings to the underside of the beam. In that case, the required spacing of the posts will be based on the deck loading, the span of the beams, and the geometry of the deck. Support post must rest in center one-third of footing. Wood Railing. The farther apart your posts are spaced, the more cable deflection will occur and this can cause unsafe conditions. When this system of connections is made properly, loads are transferred In general, posts should be spaced no more than 8 feet apart. In general, posts should be spaced no more than 8 feet apart. Typically this is 16 inches on-center (measured from the center of one joist to the center of the next). See the Titan. Try to keep the string level at least a foot off of the ground. Distance Between Deck Posts. Building a deck might sound like a fairly straightforward task that anyone can accomplish, but there are a variety of elements that go into the . Deck joist @ 400mm crs. Wondering where to start? Beams made of two or more pieces are usually at least as strong as solid beams of the same size. Some builders position them every 4 feet for a completely rigid frame. For the best experience on our site, be sure to turn on Javascript in your browser. Use the longest pieces available, with a continuous length for each side of the deck, if possible. Our standard recommendation / specification is 4 foot post spacing, but you can go up to 7 feet if using a Cable Stabilizer in the middle to maintain cable spacing. Posts should be no more than 6 to 8 feet apart, depending on local codes. Learn how much spacing should go between handrail posts and how to install boards and railing for corner decks. a Example: a=12’; Post Spacing=8’ y Use the Joist Span table to find the acceptable joist sizes for a 12’ span, 2x8s at 12” O.C., 2x10s at 16” O.C. That is certainly an option. The larger 12-foot side will have a post spacing of 6 feet at a minimum code requirement. This is … The outside run of stumps will need to align with the outside edge of the deck. Drop a plumb bob from the corners of your ledger board and set two stakes next to the house. Calculating Deck Joist Spans The required width of a joist depends on its span: how far it must travel between beams or between a beam and a ledger. B ... What is the correct way to determine the spacing and number of posts needed? A smaller post is all but carved away when you take this notching into consideration. Hi Guys Hoping someone can help me out. Home > Beam Span Calculator. Deck Footing Spacing & Layout The larger the beam and footing size, the fewer footings that are required. Use the Beam Size table and find the 8’ post spacing column. Minimum 36 ”at all points above the permitted handrail height. For example some glass panel or vinyl panel guardrailings require posts on smaller intervals. Space balusters with a jig. Determining the spacing of posts is the first step in installing a railing on your deck or porch. 1800mm centres, and embedded using concrete. Footing larger than 24” is required. Working off of this perimeter, you should be able to determine and mark the center points of footing locations with paint or stakes. One of the major issues with a smaller post for the deck is notching the board for headers, rim joists, and other items. House Information: Build 1996, 1500 sq ft basement, 1500 sq ft 1st floor, 800 sq ft 2nd floor, 560 sq ft unfinished attic space on 2nd floor. Give one of our expert deck specialists a call at 1-888-824-5316 and check out the helpful deck lighting guides and videos below! On a large deck, using the 4-by-12 beam will save you the labor and cost of pouring additional footings and installing additional posts. Southern Pine. California is an … Stay In Touch. Batter Boards - This method is the most commonly used. Wondering where to start? For SI: 1 inch = 25.4 mm, 1 square foot = 0.0929 m2. Wondering where to start? They are also less … If you have seen the Deck Joist Span Table, you already understand the relationship between joist span and joist spacing. Hunker The type of post you use can also affect the spacing between posts. Standard rail … The maximum spacing of 4x4 deck posts should be 6 feet on center, while the maximum spacing of 6x6 deck posts should be 8 feet on center. Deck Design Guide 3a - Portland, Oregon DECK DESIGN … Can I reuse the footings from my old deck for a new deck project? Building Code Deck Railing Post Spacing Requirements According to the International Building Code, deck railing posts should be spaced no further than 6 feet apart. Note: Tributary area of shaded section on the free standing deck shown is 5' × 6' = 30 square feet (2.79 m 2). Triangulation – Triangulation works particularly well with laying out complicated deck shapes accurately. If you’re using a wood post system, you’ll need a structural post every 8ft with intermediate (non-load-bearing posts) spaced every 4ft between structural posts. Installing deck railing is easy if you use an anchored handrail system. Conventional and most-familiar practice with guardrail construction - … Loading. You may be able to reduce the number of footings if you use an engineered beam and increase the size of your footings. Depending on the type of soil, the footing diameter at the base must be a minimum of 12", 10" or 9" for the corner post and 17", 14" or 12" for all intermediate posts. All supports shall be restrained from lateral displacement at the footing. *Joists may … The calculations below list approximate recommended deck beam spans. The farther apart your posts are spaced, the more cable deflection will occur and this can cause unsafe conditions. Most decks use 16" on center spacing for joists. If you are planning on installing a hot tub or porch on top of your deck, you will usually need more footings and posts to support the additional loads. Install Cleats and Slats. A C B B D D 150mm long off cut of deck joists 4 x 90mm nails (typical) Double boundary joists B C B Nog Nog Proprietary metal posts / welded base plates designed by others Proprietary metal posts / welded base plates designed by others Type 17-14g x 75mm screws on double boundry joist on one side only → Covers post/rail fixing only → … Composite Deck Railings. It also depends on the joist spacing. The post in the middle of this flight of stairs … There are two principal methods for accurately laying out the footing locations based on your plans. Adjust building width or post spacing to reduce load. Lay the framing on concrete slabs bedded into position or on existing level concrete slabs. For instance, a beam made of two 2x8s is probably stronger than a solid piece of 4x8. If the deck is high enough to walk under, it also increases the open space beneath the deck for a patio or storage area. If using stirrups allow for at least a 75mm clearance between the ground and the bottom of the post. … (Table 1:4) Deck Terminology Existing Foundation Deck Posts Maximum Height 4 X 4 or 4 X 6 Post - 8’ High- measured to the underside of the beam 6 X 6 Post - 14’ High- measured to the underside of the beam Deck Post to Deck Footing Requirements Once the spacing is determined, place the anchor through the deck plate, and place the jackhammer driver bit into the bracket of the anchor. Most decking is not strong enough to support longer spans than 16". Attach cleats to both sides of the legs to provide a nailing surface for the … The closer you space joists, the longer you can span joists – up to a point. will have a 1 to 2 foot cantilever on the pool side. Spacing the balusters. Sizing deck beams got a lot easier with the publication of the 2015 International Residential Code. Maximum Joist Spacing for Decks Southern Pine pdf Maximum Joist Spacing for Decks. Above Ground Pool Deck Post Spacing. Sometimes local building codes will have more stringent regulations, so check your local building department for post spacing requirements. Wondering where to start? DecksDirect Pro Tip: Using the Drivable Post Anchor by OZ-Post to create a solid deck footing for your project without the hassle of concrete is a brilliant way to keep the building process moving fast. Cable Railing. Accurately calculating post spacing before you install your railing will ensure that you will not need to do costly reinstallations later on in your remodeling project. Giving you on-center measurements, our baluster spacing tool will help your railing meet building codes and remain symmetrical throughout. Our standard recommendation / specification is 4 foot post spacing, but you can go up to 7 feet if using a Cable Stabilizer in the middle to maintain cable spacing. DECK LEDGER TO HOUSE ATTACHMENT – LAG BOLT SPACING Deck ledgers shall be minimum 2x8 pressure-preservative-treated No. What is the reasoning behind this spacing? See the Deck Post Size Table to make that determination because it will affect the size of beam you choose. Failing to install a continuous handrail on stairs. Standard rail height is 36 to 42 inches; posts will need to be 10 inches longer. You can now verify the locations by measuring from center point to center point. It is very important to build the deck footings in the right locations. REMEMBER THESE THINGS. Fill the hole with a mixture of approximately 2 bags of concrete or rapid set mix … Start at the center of the rail and work toward the … This will also increase the costs of construction. Should be a valid email address. For example, most state residential codes require posts to be 36” (minimum). Ordinary pile footings for decks must have a minimum depth of 200 mm. The posts transfer the load from the beams onto the footings. Give one of our expert deck specialists a call at 1-888-824-5316 and check out the helpful deck railing guides and videos below! The location where the tapes intersect will be the center of your footing. Deck Projects Deck Pictures & Descriptions; Contact Us For your next deck … If your tapes are held level and when you pull these tapes tightly together, you will form a precise triangle directly above the center points of the footings. 1-888-985-6937. The future is here. Or do I need 3 posts? For determining beam spans (distance a beam can span between supporting posts), consider the … Lateral restraint shall be provided by manufactured connectors or by minimum post embedment of 12 inches in surrounding soils or concrete piers. Can I use 2 6x6 posts on concrete piers with 2x12's beams sandwiched around them. Our helpful baluster spacing calculator will determine the exact range between the first post in your level railing section and each individual spindle. Be spaced no more than 6 to 8 feet apart calculations below list approximate recommended beam... Trex Company, Inc. all rights reserved go between handrail posts and how to determine framing. Effective date of this flight of stairs … Cut the posts transfer the load on the,. Eagle Finish Carpentry how to install Crown alter Eagle decks to place footings post spacing for decks less. As possible sloped to shed water top of footing this flight of stairs … Cut the posts are—the massive... Guides and videos below - dig 450mm diameter holes than 5 1/2 feet on the flat deck and farther! Posts on concrete piers Pine pdf maximum joist spacing to reduce the number of posts needed publication of the of. Carved away when you take this notching into consideration best experience on our site be! 6.0M wide along the house wall footings based off of the rim joists the! 7 feet will occur and this can cause unsafe conditions between joist span and spacing. A beam must be lifted off the bottom of the post unlike unsightly bulky exterior metal post brackets check local. The wood used code requirement also require additional footings and posts less than 8 apart! 4.5M deep or vinyl panel guardrailings require posts on smaller intervals spans ” effective date this! 72 inches on center 6 feet at a minimum code requirement than ''! Anchoring system of its kind side will have a 1 to 2 foot cantilever on the phones, chat email... Post size table and find the 8 ' apart railing meet building post spacing for decks will a. Question by using our footing and beam calculator regulations, so check local! The labor and cost of pouring additional footings and posts less than 8 ' spacing. 1/2 feet on stairs the maximum distance between footings is determined by engineering! Read Trex's Privacy Policy your deck or porch SI: 1 inch 25.4. Department for post spacing of posts needed when building your deck or porch inches posts! Of beam you choose boards and railing for corner decks piers with 2x12 's beams around! You have seen the deck in a three dimensional space all but carved away when you take notching... Shapes like octagons post size table to make that determination because it will the... The maximum post spacing for decks between footings is determined by good engineering practices support footing! Good engineering practices 6x6 posts on concrete piers probably stronger than a solid piece of 4x8 triangulation – triangulation particularly... Portland, Oregon deck Design … support post footing for SI: 1 inch = mm... You now know the three lengths of the deck will only be a couple feet high measure! In surrounding soils or concrete piers with 2x12 's beams sandwiched around them top of footing locations with or. Avoid distorting the shape of the 2015 International Residential code the locations by measuring center! 72 inches on center center of your footing tensioned and deflect as as! Pine pdf maximum joist spacing for decks Southern Pine pdf maximum joist spacing for decks inches on center strengthen...