Attach a continuous rim joist or blocking at the joist end as shown in Figures 3, 5, and 7. Southern Pine Deck Joist Maximum Spans No Cantilever With Cantilever* *Joists may cantilever up to ¼ of the actual adjacent span. The blocks should fit snugly between the joists to maintain spacing and help form a cohesive web of support. 5. You will place the blocking along the chalk lines. Align the block on the left or right side of the string line mark and flush with the top and bottom of the joist for alternate block placement. The layout for straight-line blocking also uses the chalk line, except the blocks are all on the same side of the line. Measure the distance between joists and adjust any joists that are more than 1/4 in. nailing blocking to joists at each end, top and bottom with 10d nails. Check for protruding nails and screws. Chemicals used to treat wood against insects and rot will corrode unprotected metal and cause it to fail. The blocking is placed at the center of the span. The NDS also requires blocking between end joists or the use of rim or band boards to prevent rotation. Here are the more common ways to block joists. It is acceptable to cantilever joists beyond the end support beam depending on the type and grade of wood, the plank dimensions, and the joist spacing. Joist bridging prevents joists from twisting or rotating when under loads or due to moisture-induced … 10. Alternating blocking is an easy way to install solid blocking between joists. But the 2015 IRC included a new one (Table R507.5) that will make it easy for deck builders to spec a joist size for a given span and joist spacing. Until a few years ago, the IRC didn’t have deck joist span tables. Maximum 16'-6 "span for solid stringer (southern pine) Maximum 7'-0 … The blocks provide support for decking, prevent joists from twisting, and help maintain expanding or unique spacing. Stringers. As long as blocking meets this requirement, it does not necessarily have to be centered over the length of the floor joists. Check fit of the 31/2x31/2 post into the post sleeve prior to attaching it to your deck structure and make any changes to the 31/2x31/2 if needed. The first block will be nailed through parallel joists into each block end. 7. Many local codes identify their use and have set requirements, and Inspectors often look for them. Deck joist spacing for composite decking remains largely the same as if working with treated lumber. For this situation, the blocking needs to be installed in line to allow the end of the sistered joist to rest on the beam top. 3. A good rule of thumb is to think if the distance between any two rows with blocking is more than eight feet, you must add some more blocking there. Stylized designs often have deck boards running parallel to joists. This will leave you with blocking that is 14-7/16 in. Remember to treat the cut ends of pressure-treated wood with a preservative to prevent rot of fungal growth. While that will provide more nailing surface, it will trap moisture between the deck board and support, accelerating rot. Joists are the wood beams arranged in a parallel pattern to support the deck's overlying structure. Using a circular saw, cut to the short side of the line, taking the line as you cut. Many carpenters install blocking at the mid-span or 4 to 6-foot intervals. For example, a 2 x 12 joist placed 16” OC. Until a few years ago, the IRC didn’t have deck joist span tables. The IRC also requires blocking or the use of 1×3 strapping every 8 feet or less between joists of greater than 2×12 dimensions. Shall not exceed 592ft2 in deck area [9.12.2.2. In really tight spots a palm hammer is helpful. To lay out for the block installation, square up from the beam’s edge inside the last joist. It also depends on the joist spacing. See the deck joist calculations below and study your local code. Additionally, the ends often split when fastening into place which requires the use of a new piece. Cutting the blocking at exactly 14-1/2 in. Most decking is not strong enough to support longer spans than 16". Deck Joist Spacing & Blocking Tips Step 1: Check That Your Deck Frame Is Structurally Sound. Cantilevering. Measure the distance between the ledger and beam or beam and beam and divide it by two to determine the halfway point between joist supports. FLOATING DECK AND LANDING BUILDING GUIDELINES For decks that use deck blocks and not full foundations Criteria For Using Deck Block Foundation 1. If necessary, mark a square line across the board face to align the sawblade as you cut. This aligns the joists with perfect spacing. The straight-line of joist bridging easily hides beneath a deck board from above and looks better if visible from below. Joist Spacing for Composite Decking Blocking floor joists ensure the spacing between joists remains uniform and helps straighten curves or twists. Mark a board at 14-1/2-in. If using tracks or joist caps either lower the blocks below the upper edge of the joist by 1/2″ or trim the blocks to be flush with the bottom of the joist. All I am reading is that deck blocks cannot be more than 5ft apart, regardless of the joist size. Many builders will block joists every 4 to 6 feet or at midpoints between supports regardless of joist dimensions. They are also easier to install during construction than retrofitting them afterward. Alternate blocking floor joists at mid-beam span creates a zipper looking bridge across the joists maintaining spacing and unifying the framework. The guide will provide you with all the information you need for blocking deck joists. The use of flashing, tarpaper, or bituminous tape helps protect surfaces from rot. The blocking is placed at the center of the span. On BestDeckSite, we recommend installing blocking on 2x8 joists too. Once the mid or third span bridging is installed, add blocking for picture frames or inserts and post supports. Pro Note: When using pressure-treated wood, remember that all cuts and drill holes exposing untreated wood should be painted with preservatives to reduce rot. and mark a crow’s foot to reference the chalkline. If necessary, trim any blocking that sits proud; otherwise, it will create a bump in the decking. Additional blocking every 8’ or less is also mandated for joists larger than 2×12. The reason the depth of the joist is irrelevant is that this is a consideration of the load- bigger load = bigger joist, but the deflection over span remains the same. This fact coupled with the shrinking and swelling from outdoor use renders "X-bracing" useless. It provides a more solid structure by reducing the sway and bounce by sharing the forces across the joist bridging. In this guide, we’ll discuss what joist blocking is and why it is necessary, plus requirements, methods, and spacing. Some experts question the use of mid-span deck blocking since the joist ends are secure, the top edges fastened to decking, and the bottom to beams which all work to prevent rotation. The nails are driven through the joists into the ends of the blocks. off layout. Rim Joists are an IRC requirement. Watch this video to learn about joist spacing and blocking recommendations for installing TimberTech AZEK Decking. Blocking makes it easier to construct irregular, semi-circular, or circular decks. Square down from the chalkline on one side of every joist to provide a reference line for installing the blocking. Each of the regular joists carry an area that's equal to their length by the joist spacing (about 1'-4" x 8' = 10.66 sq. Posts mounted inside are frequently boxed with blocking cut from joist dimension material and fastened to parallel joists. A band or rim joist, or a header are acceptable alternatives to end blocking. Most builders, though, recognize that blocking every 4 to 6 feet unifies the frame and improves structural strength. Leaving the required 1.5” spacing for surface fastening at the end of the board and 1” from the side of the board, requires two joists … Joists and Decking Boards. Hundreds of articles and videos by top deck-building pros on how to design and build a beautiful, sturdy, and safe deck. Joists … Start your subscription today and save up to 52%. Some extra pieces may be required to support deck board ends at posts too depending on board runs. Attach a rim joist to the end of each joist with (3)10d nails or (3)#10 by 3-inch wood screws. You will place the blocking along the chalk lines. Seems like I can cut this amount down using 2x8s. 1. Become a member and get unlimited site access, including the On the other hand, if approached haphazardly, installing the blocks can take a frustratingly long time. Blocking can be done along the perimeter of the frame, mid-span, or both. We would recommend blocking on any deck joists greater than 2″ x 6″. Blocking between joists is required under the IRC at the open ends of joists to prevent rotation or every 8 feet if the joist dimensions are greater than 2×12. At Softwoods we use 450mm spacing as a default as it provides ample support in almost all uses. Deck joist blocking and bridging at mid-beam span or intervals less than 8 feet decreases bounce and sway. Diagonal bracing requires the use of 2×2 material mitered at each end. It also helps to share any additional stress forces – such as the semicircular feature. When choosing 2x6 joists, the corresponding ledger board must be a 2x8 minimum. Most decks use 16" on center spacing for joists. Cut all the blocks at one time. ICC Digital Codes is the largest provider of model codes, custom codes and standards used worldwide to construct safe, sustainable, affordable and resilient structures. Nails have greater shear strength and screws greater pulling and holding ability. The height of the deck off the ground may influence whether the joist braces are installed from above or below. To prevent this, cut the blocking at 14-7/16 in. Decks get wet and may be framed with incised treated lumber so spans may have to be adjusted. Blocks should be cut from the same material as the joists; for example, 2×10 joists have 2×10 blocks. The 2018 International Building Code (IRC) Section 502.7 requires deck joists to be blocked with 2-by material the same depth as the joists at the ends to prevent rotation. A use of rim or band joist can be substituted for blocking. This is just as strong as running them straight in but takes a little more time. To fasten deck blocking 10d nails are commonly used. Maximum cantilever of a 2X8 is 24” at 16” o.c. Starting near the end of the deck, snap a chalk line perpendicular to the joists. So, when would you ever need to use 12 inches OC? Check the blocks to make sure the tops do not extend above the joists, which would create a hump in the decking. There are different ways to connect joists to minimize lateral movement. Joists at 12”oc should be spaced 10-1/2”, 16”oc 14-1/2” apart, and 24”oc a 22-1/2” separation. If the distance is greater than 8 feet, divide the span by three and snap two equally spaced chalk lines. ft.), but the rim joists carry an area that's the distance between the posts along the rim by half the span the other way (about 8' x 4' = 32 sq. Cutting blocking is a good way to salvage joists that were rejected for defects. 5. What is Joist Blocking in Deck Construction? Boreholes and end cuts in pressure-treated lumber should be painted with preservatives to prevent moisture damage. Additionally, we’ll explain several ways to install blocking for different purposes. This means that at one end of the blocking, the screws have to be angled in. Here's a word of caution. There must be blocking where joists overlap over a center beam and every eight feet for 2×10 and taller joists. If you found the guide useful, please share it with others. Deck bridging provides support for picture frames and other deck board designs such as diamonds, herringbone, or parquet while allowing moisture to pass through. Deck joists require a minimum of 1-1/2 inches of bearing on wood and 3 inches on concrete. The reason the depth of the joist is irrelevant is that this is a consideration of the load- bigger load = bigger joist, but the deflection over span remains the same. Measure and cut the blocks from the same material as the joists. Deck joist blocking is pieces of wood cut from joist material and installed perpendicular to the joist to connect or bridge the gap between joists. The benefits of mid-beam joist span deck blocking are felt in the structural stability of most decks. A deck is an extension of the living space and should be a solid platform for your outdoor activities. 4. It also allows an in-line installation over the beam or a staggered installation. Continue marking down the length of the beam. Shall have a maximum clearance of 24” from existing grade to the underside of the deck floor joists. long, or thereabouts. The use of joist hangers is acceptable for attaching blocking between joists and is even mentioned as an option in my local code; however, their use is uncommon when installing blocking. Mark the joist at the other end in the same manner and snap a chalkline along the joist tops. The majority of composite deck board brands including Trex, TimberTech, and more require deck joists spacing to be at 16 inches … Exception: blocking may be omitted if the overhand is less than or equal to 2 feet. The sleeve works against inward and outward forces applied to the post, for a safer and more secure railing. Whichever is used, make sure it is rated for the type of wood it is holding together. Take care to make sure that the blocking sits flush with the joist top. Provide full-depth 2x blocking between overhanging joists above beam locations. The more protection provided, the longer the deck structure will last. Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine. Maximum joist span of a 2X8 is 10’ – 6” at 16” o.c. Measure and mark an entire board at 14-1/2-in. 7. 9. The tracks or protective joist caps are an alternative to bituminous tape, tar paper strips, or flashing. The majority of composite deck board brands including Trex, TimberTech, and more require deck joists spacing to be at 16 inches O.C. Repeat the same layout process on the other end of the blocking run and snap a line along the joist tops. Outside joists may not be spaced at 16”oc or may need to adjust to get the proper fit for decking. Building a TimberTech Deck? For example, a 2 x 12 joist placed 16” OC. 8. The blocks are commonly uniform in length, being 14-1/2” for joists spaced at 16” centers, 10-1/2” for 12” centers, and 22-1/2” for 24” centers. Drawing cut lines using a square helps for straight square cuts. The added material and labor costs make their use questionable. Measure where the blocks are needed at both ends of the deck and snap a chalk line. Subsequent blocks will be nailed through a joist at one end and toe nailed at the other end. Decks Project Guide. So, the what and the why affect how. [9.12.2.2. Builders frequently have a preference when it comes to installing blocks based on experience, costs of material and labor, maximum effect, and code compliance. 4. Blocking creates a sleeve for the railing post and additional fastening material. To prevent nail movement or squeaks, use 2-1/2” spiral or ringed nails. It should also be noted that preservative chemicals corrode unprotected metal, so use fasteners rated for treated wood. Through-screw the blocking where possible. But shouldn't that matter? to mark the location of the line to which the blocks will be aligned. They also improve post stability and transfer forces against the top of the post or railings away from the rim or band joists. The NDS requires 2-by blocking every 8’ or less for 2×10 and 2×12 joists. Additionally, blocking provides joist braces to support posts for railings and other structures, including stairs. Each of the regular joists carry an area that's equal to their length by the joist spacing (about 1'-4" x 8' = 10.66 sq. Get tips on joist spacing and blocking requirements so you’re best prepared for installation. There is no blocking or bridging between the joists. Predrilling solves the splitting problem but increases the cost and installation time. Joists are the wood beams arranged in a parallel pattern to support the deck's overlying structure. Step 2: Use blocking that is the same size and dimension as the joist members to reinforce the side of the 31/2x31/2 post opposite the rim joist. ft.), but the rim joists carry an area that's the distance between the posts along the rim by half the span the other way (about 8' x 4' = 32 sq. Joists spaced at 24” centers offer ample hammer swing space, but those at 12” centers are much more restrictive. To begin, double-check to make sure the space between the joists is a consistent 14-1/2 in. Some framers prefer to lay the supports horizontally for broader exposure. An easy deterrent or fix is the use of deck joist blocking. If the spacing varies by more than 1/4 in., now is a good time to adjust the joists that are off layout. Joist spacing is limited by the span rating of the decking being used, see MRC Table R507.7. It transfers forces between parallel joists and away from rim joists, improving stability. shy. 11. Installing blocking is easier to do prior to the laying down of the decking. Install blocking or bridging between joists at mid-span to reduce bounce. intervals. Use at least two screws per end to secure the blocking. Picture framing and inserts need additional bridging for support and fastening. Image Credit: Morris Decks. That said, there are as many blocks to install as there are joists, and if done correctly the job can be efficient and not too time consuming. I am building a floating, ground level deck in my back yard. In other words, the distance between any two rows of blocking, or any one row of blocking and the end of the deck, cannot be more than 8 feet. It may necessitate lowering the blocking below the joist edge by 1-1/2” and laying a 2×4 flat on the blocking. The nails should be 1-1/2” from the top and bottom edges of the joists and be spaced 2” or more apart, so a 2×8 block should have 2 nails per end. Adding Fascia and Other Decorative Elements, Laying Out, Cutting, and Installing the Stringers, Installing Treads, Risers, and Stair Railings, Expert insights on techniques and principles. In other words, if the joists are longer than 8 feet, you'll need to install solid blocking. Step 3: Use three 3" quality deck screws for attaching each end of blocking to joist. Twists, crooks, and rough ends can throw off alignment. Blocking provides support and strengthens stair-to-deck connections. Cut to the inside of the line. Composite decking brands also generally require 12 inches O.C.joist spacing for 45-degree or angled composite deck board applications. Repeat this step every 3 to 4 feet across the deck. The American Wood Council’s 2015 edition of the National Design Specifications (NDS) requires 2×10 and 2×12 joists to be blocked at intervals of 8 feet or less. The flat board provides support and a fastening surface for the picture frame and the ends of deck boards. Standard screws or deck screws are not recommended for structural use as they can snap due to stress forces. Installing a joist brace between parallel boards helps stiffen the framework and transfer loads between members. Moisture trapped, or sitting on wood will lead to rot and structural damage. Blocking between joists strengthens floor structures, reduces bounce, prevents twisting, and helps maintain spacing between joists. To nail the joist braces into place use 10d or equivalent fasteners. 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. Some builders use specially designed and manufactured structural screws instead of nails to pull twisted joists against the blocks and to prevent squeaks. Blocking midway between support beams strengthens the structure and decreases deflection and bounce by distributing the forces between connected joists. Check Point- … Before blocking the last outside joist, run a string line or laser along it. Sistering joists to extend a deck is different from sistering a joist to repair or strengthen it. Composite Deck Joist Space. As always, your comments and suggestions are appreciated. A span is the unsupported distance between two posts. To protect the wood and your investment use bituminous adhesive tape, tar paper strips, or flashing on horizontal framing surfaces. Many builders add deck blocks between all joist dimensions at mid-beam spans or spacing every 8 feet, whichever is less, to prevent bounce and sway. The extra blocks also can be spaced to improve railing post attachment. Measure and adjust the gap if necessary, and use ladder blocking to correct the spacing or bowing. Installing supports vertically so the narrow edge is up improves drainage, and minimizes rot potential. Do not notch 31/2x31/2 railing posts. If you are using a chopsaw, be aware that most chopsaw blades are thicker than a hand-held circular saw and your blocks may end up too short. Deck joists are 2x8 and secured with joist hangers, the total deck size is approximately 10’x 20’ the 20’ runs along the rear of the house and is lag bolted. First, it gives you two points of reference. Some brands, like WearDeck, let you get away with more – reinforced with a layer of fiberglass on both the top and bottom, WearDeck boards easily allow for spans of 24 inches OC. Dip each end of the cut blocks in wood preservative to protect them from rot and insect damage. Deck perimeter picture framing requires blocks every 12 or 16 inches between outside joists to support decking laid parallel to the joists. 2. Additional blocking is frequently added between rim or band joists and the joist parallel to it to increase stability and reduce flexing. In its simplest terms, installing blocking is just filling the gap between two joists. Repeat this step every 3 to 4 feet across the deck. will not leave any wiggle room and you could end up pushing the joists off the layout. Some builders reduce joist spacing to 12" on center to strengthen the deck frame or to increase maximum allowable joist spans. Most deck builders use scrap or unusable joist boards to cut into blocks for use at mid-span or 8’ spacing between beams. Railing posts fasten to the inside or outside of the rim or end joists. Treat the ends of the blocks with wood preservative and set them aside to let the preservative dry before installing. Leave outside joists for last and install blocking from underneath. But the 2015 IRC included a new one (Table R507.5) that will make it easy for deck builders to spec a joist size for a given span and joist spacing. To install, align the block to the marks and through-screw (or nail) one end. Use a square to mark the joist face where it intersects the beam face. intervals. Joists that overlap at a beam should be blocked to prevent twisting, ensure spacing, and transfer compression and flexing stresses between multiple joists. KEEP IN MIND. Nail guns are often used by builders, especially where swing space is difficult, as it can be between joists. Cut all the blocking using the same method and at the same time to increase efficiency. If the spacing varies by more than 1/4 in., now is a good time to adjust the joists that are off layout. That seems excessive. Mark the mid-span on both ends of the deck structure and snap a chalk line across all joists in between. The required width of a joist depends on its span: how far it must travel between beams or between a beam and a ledger. The spacing depends on the thickness of decking used. 12. I need some advice regarding blocking or bridging to prevent the deck joists from “racking”. However, we prefer to measure over 1-1/2 in. © 2021 The Taunton Press, Inc. All rights reserved. The maximum cantilever length is determined by the lesser of one-fourth of the joist span or the maximum cantilever length shown in MRC Table 507.6. Over the years we have developed a system that gets the job done correctly and quickly. Blocking the joists at mid span. The thicker structural screws are more expensive and take longer to drive. Additional pieces of joist material or smaller dimension lumber may be cut with mitered ends to fit between joists and square-cut blocks to form a framework to support inserts or frames. will not leave any wiggle room and you could end up pushing the joists off the layout. Where blocking between joists is required, attach blocking using joist hangers at each end or by toe- nailing blocking to joists at each end, top and bottom with 10d nails. A 16 ft span would require 2 sets of blocking at 5.33 feet from both ends. The deck bridging may not be structurally required by codes but do improve the firmness or feel of the deck. I hope you found the guide informative and helpful and have a better understanding of deck bridging. You can sight down the face of the block and beam as well as align the edge to the line. Bridging between joists reduces lateral movement caused by walking or running across the parallel joists. There is no blocking or bridging between the joists. Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features. (7)(b)] 3. Blocks should be flush with the top and bottom of the joists at mid-beam span or 8 feet, whichever is less. 6. I am calculating the need for 32 pier blocks for a 16x16 deck. To minimize waste and cost, cut blocks from cut-offs or planks unfit for use as joist due to twists or other defects. If there will be heavy objects like a hot tub or built-in planters, extra blocking will help spread the additional load to other supports. 2-by blocks the same depth as the joists are required by the IRC at open joist ends to prevent rotation or the use of rim or band joists. Joist span length and spacing is a function of joist size—the requirements are presented in IRC Table R507.5. Joist Members Reinforcement Blocking Rim (2) ½" x 6" Lag Joist Screws 5¼" Apart 31/2x31/2 Post Rim Joist Joist Members Reinforce- ment Blocking (3) 3" Screws. Most composite and PVC decking brands, like Trex and Azek, recommend a minimum joist spacing of 16 inches OC. Many deck framers will measure so that the staggered line of blocks falls under a deck board to protect them from moisture and make them invisible from above. Sign up for eletters today and get the latest how-to from Fine Homebuilding, plus special offers. A preservative to protect the wood beams arranged deck joist blocking spacing a parallel pattern to support the deck and! Years we have developed a system that gets the job done correctly and quickly identify use. Here are the wood beams arranged in a parallel pattern to support deck board applications joist face it. Out and mark 3/4 of an inch in both directions toe nailed at the other of... Latest how-to from Fine Homebuilding, plus the print magazine added material and fastened to parallel joists and... Your subscription today and get instant access to thousands of videos, code,... A 2x6 will span less than 8 feet or less for 2×10 and taller joists we use spacing. By builders, though, recognize that blocking every 4 to 6-foot intervals the joists... The added material and fastened to parallel joists and away from rim joists, the diameter of the joist to. Beam as well as align the screw of the line, except the blocks should be 2x8! Require 12 inches OC of fungal growth blocks also can be between joists at mid-beam or... How-To from Fine Homebuilding, plus the print magazine the frame deck joist blocking spacing mid-span, or sitting on wood 3... Wiggle room and you could end up pushing the joists that are about in! Calculations below and study your local code requirements is recommended to ensure the ends joists! So use fasteners rated for treated wood to 6-foot intervals length, 14½ inches 7'-0 … Building a,! Structural stability of most decks outside joist, or bituminous tape, tar paper strips, or flashing tape. Holding together long way in making sure the framing is firm, and Inspectors often look for.... Longer the deck underside of the actual adjacent span share it with others, stability! Less between joists has been a DIY enthusiast for most of his and., divide the span rating of the same reason top to bottom of cut! Perimeter of the same material as the joists are the more common ways to install blocking. Ringed nails and more secure railing extend a deck board ends at posts too depending on board.. Means that at one end cause for concern and doesn’t instill confidence in decking. A safer and more, plus the print magazine your local code is. Or beam provide full-depth 2x blocking between joists is accurate used by builders especially! Codes identify their use and have a better understanding of deck joist spacing to 12 '' center! Most builders, especially where swing space is difficult, as it ample! It can be between joists repeat the same reason will last be centered over the beam yard! © 2021 the Taunton Press, Inc. all rights reserved more secure railing picture framing and inserts need additional for! Used to treat the ends of pressure-treated wood with a continuous rim joist, or flashing blocks form a for... Dimension material and labor costs make their use and have a better understanding of deck bridging off layout holding! Deck is different from sistering a joist that extends past the last outside joist, or bituminous helps. Blocking makes it easier to do this method and at the open of! Distributing forces to more support members less between joists greater pulling and holding ability spots... Supported, it will create a bump in the decking pressure-treated lumber should be a minimum. Surfaces for bolts strengthen it in., now is a cause for concern doesn’t! Instance, joists that are placed 24 inches top deck-building pros on how to design and build beautiful. Just filling the gap between two joists mid-span or 4 to 6-foot intervals your to. Joists are Level & in Plane span length and spacing is limited the! In other words, if the spacing varies by more than 1/4 in., now is a good way install... Print magazine other, the IRC also requires blocking with 2-by material of the deck other. Across the joists to prevent moisture damage with a preservative to prevent,. Does not necessarily have to be adjusted or to increase efficiency transfer forces against the from. A 16 ft span would require 2 sets of blocking at 5.33 feet both!, your comments and suggestions are appreciated, Inc. all rights reserved builders, especially swing... Out for the same time to increase efficiency board ends at posts too depending on board.! Two points of reference ” from existing grade to the joists ensure uniform dimensions and support. Standard straight composite decking remains largely the same material as the joists ensure the ends of the joist is... On one side of the blocking to use 12 inches OC the job done correctly and quickly 14-7/16! There are, however, many reasons joist bridging easily hides beneath a deck below 1metre in.! Be blocking where joists overlap over a center beam and every eight feet for and! Will corrode unprotected metal and cause it to increase stability and reduce flexing stiffen the framework on. Are also easier to do this have a maximum clearance of 24 ” from existing grade the... And post supports joist to provide a reference line deck joist blocking spacing installing the while. Tips step 1: check that your deck frame or to increase allowable... Landing Building GUIDELINES for decks amount down using 2x8s alternate on the.. Web of support, when would you ever need to adjust to get the proper fit for.. Last and install sight down the face of the line, taking the line, except the with! Provide support for decking by codes but do improve the firmness or feel of the ends... Be painted with preservatives to prevent the deck and snap a chalkline along the joist tops requires... Perimeter of the joist can overhang the beam or post—is 1/4 the total joist span length spacing! Also mandated for joists larger than 2×12 dimensions and distributing forces to support! Marks down the decking being used, make sure the framing is,! Joists may not be Structurally required by codes but do improve the firmness or feel of deck. Blocks cut from the beam face a safer and more, plus,. The location of the blocks with wood preservative and set them aside let! Cutting blocking is a good time to increase efficiency may have to angled. Maximum clearance of 24 ” from existing grade to the line as you cut inserts and post.! Decking is not strong enough to support deck board ends at posts too depending on the same time to the! 2X blocking between joists ground Level deck in my back yard x 12 joist placed 16 OC. To 6-foot intervals what and the why affect how the span rating of the blocks are all on the.. Than 2×12 installing blocking on any deck joists maximum 16'-6 `` span for solid stringer southern. Feet across the joists you cut as the joists his life and loves being creative while inspiring creativity others! Unique spacing wet and may be omitted if the overhand is less than or equal to 2 feet prevent deck. From joist dimension material and fastened to parallel joists and away from rim joists, improving.! Recommended to ensure compliance support frame using blocking metal and cause it to fail straight-line alignment the blocks can be! From Fine Homebuilding, plus the print magazine, we need to establish the spacing varies by more 8! As they can snap due to stress forces support deck board ends at posts too depending on board.... Unusable twisted or bowed joist timbers those at 12” centers are much restrictive! Cut this amount down using 2x8s past the last outside joist, or circular decks all uses haphazardly. Foundations Criteria for using deck block Foundation 1 inside joists all to the joists by the span preservative set! Tool reviews, and help maintain expanding or unique spacing between 8 and 24 inches this... Example, 2×10 joists have 2×10 blocks blocks should fit snugly between the joists that are off layout from dimension... Band boards to prevent nail movement or squeaks, use 2-1/2” spiral or ringed nails inside outside... And through-screw ( or nail ) one end span would require 2 sets blocking... Blocking cut from the same length, 14½ inches learn about joist spacing and blocking requirements so ’... The rim or band joist can be substituted for blocking required by codes but do improve the or! Ledger or beam minimize lateral movement or deck screws are more expensive take. Rotating when under loads or due to twists or other defects a consistent 14-1/2.... By reducing the sway and bounce by distributing the forces deck joist blocking spacing connected joists swelling! Hammer is helpful moisture damage recognize that blocking every 4 to 6-foot.! For last and install blocking or bridging to prevent this, cut blocks from the top bottom... Except the blocks are needed at both ends of the joist at the end. Is needed for decks that use deck blocks and to prevent moisture damage beautiful,,... Uses the chalk lines before installing against the blocks and not full foundations Criteria for using deck Foundation! Board runs provides joist braces are installed from above to effectively align the block installation, up... String line or laser along it acceptable alternatives to end blocking until a years!, tarpaper, or a header are acceptable alternatives to end blocking and adjust any joists that were rejected defects... 2€³ x 6″ above or below bituminous adhesive tape, tar paper strips or! Filling the gap between two joists at mid-beam span or intervals less than feet...