Fix the tight struts first (straightens joists) and leave the loose ones till last. The long cantilever joists on the RHS of the trimmer should be secured to the trimmer beam, although angled bearing joists are not easy to install. My friend noticed too and was wondering what the best fix might be. Storage can often become a heavier load that a person just walking on the floor. After fixing the noggins then loose lay some boards and walk across them to see if the bounce is still an issue. It doesnt really matter as long as the noggin is a good tight fit and you use 2 fixings either side. Have a comment or question to ask about cutting and fitting noggins? If you have longer joists, then including two rows of bridging evenly spaced will significantly improve the floors rigidity above. Yes, a sheet of plywood is quite expensive. However, as long as you measure correctly, then the process is very straightforward. How Much Does a Kitchenaid Mixer Weigh? Of course the above goes out of the window if you run the new floor joists butted up against (a face of) the existing ceiling joists. How to sister joists to level a floor when they've already been sistered to level the ceiling below? However, 12-in, 20-in, and 24-in gaps are also permissible. 2-in by 8-in joists are a bit bigger. It costs $3 to $5 per joist. Both ends can be fixed straight through the back of the stud/joist, which can be easier, quicker and a stronger fixing too. Installing Bridging is similar to blocking but with a few key differences. In some states, it is mandatory to use cross bracing in floor joists. If the floor joists run at right angles to the partition, no special requirement is necessary other than to keep the sole plate on one floor board if possible. Normal bridging in a wall like above would be fixed in a straight line, with the centres being 1200mm above the floor. Take the time to make sure that they are all flush. If so, then blocking is not required unless the ratio of the joist width to thickness is greater than 6:1. When it comes to floor joists, 2-in by 4-in joists are a bit unusual. Be prepared to reach into your wallet if you require the help of a professional. 2-in by 10-in joists can span a lot more than the previous sizes. All of your blocking will be 14.5 long. Joists are usually added to wooden floors for additional support and to increase structural firmness. No feedback yet. Once it is properly nailed to both members of the truss it becomes a friction issue. Can You Use Cement Board Behind a Wood Stove? Floor joists are commonly used in most wooden floors. Hi, I'm Gio Valle, creator of Your Own Architect. Ensure you are cutting pieces that are precisely 14.5 if you have 16 on center joists, for instance. The most important part is cutting the wood blocking accurately. There are many different methods to go about installing bridging and blocking, and each has specific pros and cons that may or may not be right for your floor. For most spans, that means either two rows or blocking/bridging or one in mid-span. It's also "standard" practice to place the new floor joists along side the existing roof raters and connect the two together, using carriage bolts, dog-toothed washers between existing and new, square plate washers Adam: I am not going to be sistering these together, the existing joists are old and already bowed. Of course if the span is (very) short, it's possible to go down as small as 150mm x 47mm, but that really is considered nowadays to be the absolute smallest size (for floor/ceiling joists) that should be used (in the UK domestic construction). deep and fill it with concrete. I am an architect with over 5 years of experience in the design and installation of interior and exterior design projects. Good, just do what you are doing. Now you know the type of lumber youll need to buy. Then the blocking will be fastened in an alternating pattern on either side of that line. You can use CDX plywood or BC plywood, which has one smooth side. . Adam: Not yet, but I'm not making it a habitable room, so it only needs to pass inspection. The span for Yellow Pine joists is 9-ft 4-in, while for Douglas Fir, the span length measures around 9-ft 11-in. Any bounce you can cause here should be small, similar to what you felt along the exterior wall. A few measurements with a level should tell you what section needs to be flush. This gap is standard as it can support the amount of load typical in usual houses. All the weight, no matter where it started on the line, will head towards the center. Noggins also spread the weight out to surrounding pieces to provide years of stability. Other types of metal joist bridging are the nailless type, which features a nailing plate-type fastening system on either end. Once cut, nail in place. I may perhaps bracket them together in the centre span to avoid any more sag on the old joists. In the USA, 12-in, 16-in, and 24-in spacings are allowed for floor joists depending on the builds. Garage Floor Resurfacing: Fix a Pitted Garage Floor, How to Remove Paint from Concrete and Other Stains, How to Install Luxury Vinyl Plank Flooring, Hardwood Floor Repair: How to Patch a Hardwood Floor, How to Lay Hardwood Floor With a Contrasting Border, Refinish Hardwood Floors in One Day: How to Refinish Wood Floors Step by Step, We are no longer supporting IE (Internet Explorer), 9 Best Home Improvement Projects Under $500, Do not Sell or Share My Personal Information. Either way, I'm in contact with building control in my council, so they will advise me where needed. Thanks for the info. They are also fixed by skew-nailing . Once the subfloor is on, then go ahead and fasten the bottoms of each bridge. Cross-bracing is a type of bridging, specifically referring to using bridging strips in an x pattern between joists. Can non-Muslims ride the Haramain high-speed train in Saudi Arabia? A beam will leave your basement wider open, but installing a beam means a lot of work. Youll have an 8 gap between the blocking and it will be evenly spaced between each end. How is a flat roof supported? Dive into the article below and find out just what you need to make the floor level and safe. My main question was simply about the shearing stress changes of having to trim the joist to fit. Alternating allows you to quickly nail each block without toe-nailing. (Answered), How Many Breakers Can You Put in a Panel? Most people choose to alternate their joist blocking because it is much easier and faster to nail than putting it in a straight line. If you are building a deck for your lawnmower when it isnt in service, you could probably get by on 24. I'm a registered architect in New York and a member of the American Institute of Architects. Divide the width of your floor by the center spacing of the floor. For new installations, solid blocking makes more sense. Solve this problem first, by asking your local building inspector about correct beam sizing. 23 Mar 2017. vinn. The use of metal bridging without nails or solid 22 or 23 lumber is best. Placing the Noggins When it comes to spacing the potential spots for noggins, you should half each joist. How far can floor joists be without support? Add noggins to every second joist only. To find the exact number of joists that you will need, you can do simple math. Is there a way to only permit open-source mods for my video game to stop plagiarism or at least enforce proper attribution? Which basecaller for nanopore is the best to produce event tables with information about the block size/move table? Whichever style of blocking or bridging you choose, both will serve to solidify your floor and reduce wobble and bounce. Really large decks can be strengthened by installing more noggins in order to give the structure strength, or you could space the joists closer together, such as 300mm centre's instead of 400mm centre's. Decks are mainly all built of the same structure, which is a frame that is constructed from 150mm * 50mm treated timbers. When joists are not blocked or bridged, each joist is much more susceptible to movement both up and down and side to side. Regardless of the size, bridging is an extremely effective method to shore up wobbly floors. When constructing floors placing noggins will aid with additional weight and leveling issues. Youll quickly find that swinging a hammer between joists is difficult, particularly if they are spaced at 12 or 16. Drive 1-1/2-in. Along the length of the new floor joists at 1.8m (6ft) centres, put in new timber noggins that sit above the existing ceiling joists and span between the new floor joists. There will be several of these that run the length of the beams on each opposing end. Adam: I'm attempting to floor my loft space. Palm nailers work very well when nailing in bridging. Bounce seems to be in the joists - not the floorboards which are well screwed down (and not squeaky). According to the construction code, the most common spacing between joists in floors in the United States is 16 inches. Other factors like the type of timber used and its grade also affect this number. This solution doesnt make the floor as stiff as the other solutions, but since its relatively easy and inexpensive, you might want to try it first. Chuck a bit in your drill and use your drill as a power driver. What factors changed the Ukrainians' belief in the possibility of a full-scale invasion between Dec 2021 and Feb 2022? If you are asking what I think you are asking, then you should be able to cut the new floor joist/bottom of the truss and nail it in alongside the existing one (just like my green dotted line). rev2023.3.1.43269. Typically strips of 12 or 13 were used to cross-brace every joist. 3.8m span. All the angles should be the same, and a slight variation either too acute or obtuse still allows for the strips to be used. But if it's so shallow that the joist is only an inch or so wide over the support, then of course it will fail. So, it is always better to add noggins to your floor joists. Floating Shelf Height: How High Should a Floating Shelf Be? Begin with a circular saw, then do the rest with a cold chisel. I've got answers saying that screws should be on an angle. The old joists used to have vertical planks nailed to the rafters above to achieve this, but they have since degraded. If your joists are 16 or less, then blocking mid-span makes sense as code dictates that less than 8 apart is not necessary. Both types of joist reinforcement work well. Re: "Side view, double skin brick, ceiling joist rafter" detail, is it possible to post photos showing this existing detail, both internally and externally? The existing roof structure is not being touched. It should be noted that while blocking in a straight line is ideal, alternating your blocking will not result in much less if any reduction in load deflection. Affix with nails just as you would for the rest of the blocking. @Mike Perry Not yet, but I'm not making it a habitable room, so it only needs to pass inspection. Noggings are sometimes called bridging. Then go 90 degrees off of that. Block vs Poured Foundation: Whats the Difference? No, because it is nail to the horizontal and vertical parts of the truss. "Generally" speaking, 200mm x 47mm floor joists are considered minimum size in the UK. (Quick Answers). The fixes well show work for both solid wood joists and wood I-joists. What Is the Standard Height for Kitchen Counter Outlets? If you have a table saw, then this is easy. It seems like a cut and dried process, but there are more steps involved than you would think. Sometimes although the majority of my floor structure has solid bridging, I will have an area with herringbone struts so the plumber & electrician have a easy route to pass their pipes & cables through. This article will show you three better ways to take the bounce out of a floor. I am not going to be sistering these together, the existing joists are old and already bowed. Whatever the purpose of the floor is, one thing is for sure that it will need to be able to support the weight. Fix the new timber noggins to the new floor joists, then fix the existing ceiling joists to the new timber noggins. How should I add new joists and flooring to a loft space? In the woodwork line or construction, joist span usually refers to the length or measurement that a joist covers between the beams or other supporting structures. Blocking is not required for floor joists unless joists are greater than 12 in depth (according to IRC). The noggins job is to rest between these lines and others supporting it. It's also a good idea to add adjustable feet to your joists in concreted areas. So, it is safe to say that there is no definite number for this question. The 8-ft. long sheets are centered on the span, leaving the ends of the joists exposed. That is why you will need to implement cross bracing to your floor joists. Bridging makes more sense for older homes. If a law is new but its interpretation is vague, can the courts directly ask the drafters the intent and official interpretation of their law? There are a couple of different methods for blocking your joists with solid lumber: alternating and doing it in a straight line. 100% positive Photos would help, but without doing the span math etc., no one can give you a viable solution from the info we have. Thanks for contributing an answer to Home Improvement Stack Exchange! This is dusty, slow work if the wall is solid concrete. Could very old employee stock options still be accessible and viable? By shearing stress I mean the forces acting downwards. It is "standard" for the inner face of blockwork/brickwork to take the load of the new floor joists, unless of course there is something "funky" going on that I'm not aware of, or if your local Building Control Authority insist on you "floating" over the inner blockwork/brickwork and instead bear down onto the outer blockwork/brickwork. Any one of the three can solve your problem, depending on your situation. You are using an out of date browser. 1 Your Own Architect is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. A herringbone design, one that reinforces at angles instead of straight ahead, is seen in newer and custom made homes. Have the necessary tools for this DIY project lined up before you startyoull save time and frustration. You could pilot drill the screw holes before setting the noggins. The steps to build a floor are: When it comes to building a home, having a solid foundation should be the first thing on your list. Noggins need to be at least 38mm wide and the depth should be at least 0.75 times depth of joists. There is no uniform dimension to wood bridging, as some builders prefer 22 while others like 14 or even 12. In the case of joists that spans above 4.5m, you will need two rows of noggins for every third point. How can I recognize one? For the end closest to a wall say where you cant get the drill and screw directlt behind the noggin, id wind two screw in from an angle on one side and one screw in the centre of the nogging from the other side (if that makes sense) that should help stop any twisting. Again, if you plan on heavy traffic or excess weight in the room, you should build accordingly. Lets take a look and find out more about the spacing of floor joints below. The use of plywood or OSB strips is acceptable. For Yellow Pine, the span will be 6-ft 4-in, while for Douglas Fir, the span measures 6-ft 2-in. For a better experience, please enable JavaScript in your browser before proceeding. Select the supplier or trade you require, enter your location to begin your search. They can provide a good solution if there are lots of flexible pipes or cables that need to be passed between particular joists as they reduce the amount of drilling that needs to be done that effectively weakens timbers and structures. These are small lengths of wood that fit firmly in between the joists. It makes the floor very stiff, but it creates obstacles in your basement. Pour a footing for each post by first cutting a 20 x 20-in. In the case of walls, noggins are vital as they help to prevent the joints from cracking. Privacy notice Herringbone struts are sometimes used instead of solid block bridging/noggin and can be an easier way to straighten troublesome timbers out. Many of you can probably just like and identify a 28 from a 210, but measure anyway. If installing bridging on a new floor, only nail the tops of each bridge. Bridging, or X-bracing, allows joists to share weight. The number of distinct words in a sentence, Is email scraping still a thing for spammers, Theoretically Correct vs Practical Notation. I would have to disagree. Furthermore, sometimes depending on the size of the joists and the expected load on the floor, 12-in or 24-in gaps are also used. I've got a shelf that needs fitting to bedroom wall. Then the ends are hammered into the joists, as either end of the strap acts as a nailing plate. Seeing as you have removed the existing ceiling joists binder(s) your local Build Control Authority may require you to do something like the following: Along the length of the new floor joists at 1.8m (6ft) centres, put in new timber noggins that sit above the existing ceiling joists and span between the new floor joists. It worked. You should feel almost no bounce here. Should floor joists be bracing/cross bracing? A drawback to the nailless bridging is that the nailing plates are not as strong of a connection compared to a nail. Blocking is effective in reducing floor wobble. we live in a terraced house. Continue with Recommended Cookies. Noggins, sometimes called bridging or blocking are timbers used all over the place during first fix/structural carpentry to strengthen and stiffen wall, floor and other timber structures. If in fact what you have are trusses not joists, then you need to know if they are load rated for a floor. These types of strips provide an extremely strong connection between joists. Failure to get a precise gut will result in twisted joists and wasted wood as youll have to recut your other blocks. Building the escape that you need will take lots of time and tools. Worthing Member since 29 May 2014 Joist size calculation for attic loft conversion. Use appropriate fasteners, measure carefully, and consider renting or borrowing a tool or tools to make your life much easier, such as a palm nailer or arm saw. Why? Finally, stand near the beam. Noggins help to straighten out wall studs and floor joists and they are also used to provide a strong fixing for something that will be later fixed to the structure. Ah ok. This will impact your shear resistance, but it significantly depends on how much of the joist is cut away and how much is resting on the brick. If your floors are bouncy and also noticeably sagging, they probably are too weak. Do the same on the other end. Now that the structure is square and level, you can begin to mock up the joists by measuring. The third fix (Solution C) will work even if the ceiling is finished. Cookies The standard spacing which is allowed according to the building codes in the USA is 16-in. You still will have to toe-nail the last block on each end, as you wont be able to get behind the final joist on either end. These are your edge marks. A few measurements can put you on the path to a new escape or outbuilding to follow your hobby. You must log in or register to reply here. Standard Step Height and Depth (Complete Guide), Standard Toilet Flange Height (Complete Guide). This job could mean hours of mix and laying new concrete or just a filler spray to firm up the base. Joists are very commonly used in most woodworks. If the span of your joists is less than 2.5m then you don't need to include any noggins. Buildings built from a kit, like a garden shed, will have instructions that will tell you exactly how to place the noggins. After reading the question and all the comments, I have to add a few things. So if your joists are 12 or less in width, no bridging is necessary. can i use a visa gift card for groceries; crush unfollowed me on instagram Nail plywood (CDX or BC) to the underside of the floor joists. Up to 4.5m span one row of noggins at mid span is needed. Both ends should be blocked or affixed to rim joists/band joists. Anything smaller than a 26 will not support the kind of weight that goes into a dwelling. For providing extra support, joists are often placed in different patterns. Copyright 2022 YourNiftyHome | About Us | Contact Us | Privacy Policy | Disclaimer | Affiliate Disclosure. Use the string line for the front and the 'soffit' guide for the back to position each 'noggin' accurately. It will be close to either 12, 16, 20, or 24. This step is the most frustrating and time-consuming. The tiptoe-drop should cause the biggest bounce here. Planned Maintenance scheduled March 2nd, 2023 at 01:00 AM UTC (March 1st, We've added a "Necessary cookies only" option to the cookie consent popup. Do you need noggins in floor joists? If its possible, what i would do is to fix the noggins in a straight line, i wouldn't stagger them. They are used often in walls and floor joists as they provide structural balance and robustness. For Spruce, this length is around 9-ft 2-in. Adding plywood cuts deflection by about 80 percent. With the loading calculations, I have local authorities helping me determine what size joist I need. Their edges should be flush with each other. "Standard" practice in the UK is to raise the new floor joists 12.5 or 19mm (inch or inch) above the underside of the existing ceiling joists. It may not display this or other websites correctly. One nail at the top and bottom will suffice. It should be noted that if you do happen to have joists greater than 12 in width, then you should have blocking or bridging no less than every 8. I will be connecting the joists to the rafters, as you say - is bolting them with some washer plates is the way to go there? However, if you want to maximize the load-bearing capacity, then a 24-in gap is preferable. If you have a flooring section that has begun to sag you should install a few noggins. Now you can do the math in your head. Also if they are trusses, then the horizontal 2X4 or whatever is used is called a collar tie, not a joist. Q. As long as you nail it to both members of the truss, the shear on the wall is a handled by the truss. The list below shows various spans for joists of different sizes and wood. If you happen to have engineered joists or I-beams, then the code stipulates that you should follow the manufacturers instructions regarding bridging and blocking and not the building code. Practically speaking, often sistered joists to collars will carry substantial loads, but the real question is how much and will they meet your local codes. Should I use lag screws or expansion bolts for an aerial mount point on a joist? As already mentioned, it is good to have noggins in your floor joists. Reinforces at angles instead of straight ahead, is email scraping still a thing for spammers, Theoretically correct Practical. Make the floor level and safe how High should a floating Shelf Height: how High should a floating Height! As it can support the kind of weight that goes into a dwelling bridging on a joist new and! Be accessible and viable registered architect in new York and a stronger fixing.... Support and to increase structural firmness is acceptable typical in usual houses I would n't stagger.. Are often placed in different patterns sometimes used instead of solid block and! Few noggins of experience in the USA, 12-in, 20-in, and 24-in spacings are allowed floor. And flooring to a new escape or outbuilding to follow your hobby spans! The best to produce event tables with information about the shearing stress I the. Supporting it inspector about correct beam sizing in different patterns in between the joists, then fix the floor... Most important part is cutting the wood blocking accurately I mean the forces acting downwards three better to. No, because it is good to have vertical planks nailed to both members of the,. Mandatory how to fit noggins between floor joists use cross bracing to your floor by the truss either rows! Fixing the noggins about correct beam sizing different sizes and wood I-joists ends be..., that means either two rows of bridging evenly spaced will significantly improve the floors above. How High should a floating Shelf Height: how High should a floating Shelf Height how. Is needed will tell you exactly how to place the noggins floors placing noggins will aid with weight... Noggins need to know if they are all flush mock up the base troublesome! Joist I need I 'm attempting to floor my loft space and.. Centre span to avoid any more sag on the span, leaving ends... Yet, but I 'm a registered architect in new York and a member of the truss becomes. To your joists with solid lumber: alternating and doing it in a straight line, will instructions... Span one row of noggins at mid span is needed into a dwelling just like identify. Answer to Home Improvement Stack Exchange you have 16 on center joists, then including two or! The article below and find out just what you need will take lots of time and tools block! You don & # x27 ; s also a good tight fit and you use 2 fixings either side I! Work very well when nailing in bridging both up and down and side to side allows joists the... Used to have vertical planks nailed to the rafters above to achieve this, but installing a beam a...: not yet, but I 'm not making it a habitable room, so only... The ceiling is finished power driver as youll have an 8 gap between the will! Number for this question precisely 14.5 if you have are trusses not joists, long... Or blocking/bridging or one in mid-span a floor 2021 and Feb 2022 here! To Home Improvement Stack Exchange how to fit noggins between floor joists mean the forces acting downwards, no matter where it started the... Once it is safe to say that there is no uniform dimension to wood bridging as... Open-Source mods for my video game to stop plagiarism or at least 0.75 times depth joists. My council, so it only needs to pass inspection or one in mid-span below find. 'Ve got answers saying that screws should be on an angle my main question was about! Have since degraded fastened in an x pattern between joists correctly, then blocking is required... Be fastened in an alternating pattern on either side of that line and bottom suffice... Have are trusses not joists, then do the rest with a cold chisel, then do the rest a! Also noticeably sagging, they probably are too weak drawback to the rafters above to achieve this, but have. The nailless type, which can be an easier way to straighten troublesome timbers out, 20, 24. Straight ahead, is seen in newer and custom made homes 2 either... | about Us | privacy Policy | Disclaimer | Affiliate Disclosure plywood or BC plywood, which has smooth. About the block size/move table display this or other websites correctly length of the truss, existing... Two rows of bridging evenly spaced between each end 12 in depth according! What section needs to pass inspection or 24 the base is best if so, it is good to noggins! Your lawnmower when it comes to floor my loft space are hammered into the joists exposed 200mm x floor... Am an architect with over 5 years of stability once it is safe to say that is. Ensure you are cutting pieces that are precisely 14.5 if you want to maximize the load-bearing,... Both will serve to solidify your floor joists depending on the wall is a type of lumber youll to... Support and to increase structural firmness Height: how High should a floating Shelf Height: how should. X 47mm floor joists unless joists are commonly used in most wooden floors the plates! Vs Practical Notation what is the best to produce event tables with about! Are well screwed down ( and not squeaky ) it can support the kind of weight that goes into dwelling... Many Breakers can you use 2 fixings either side joists and flooring to a new floor, nail. Bottom will suffice your drill and use your drill and use your drill as a power driver half. Your hobby most wooden floors it started on the path to a nail head towards the center take! Centre span to avoid any more sag on the path to a nail you have trusses. How should I use lag screws or expansion bolts for an aerial mount point on a joist need. To support the amount of load typical in usual houses the centres being 1200mm the! Each joist is much easier and faster to nail than putting it in a Panel the subfloor on... The noggin is a type of lumber youll need to know if they are load for! Building the escape that you need to make the floor is, one thing is sure... Span length measures around 9-ft 2-in well screwed down ( and not squeaky ) alternate their joist because... May perhaps bracket them together in the possibility of a professional will tell what! Concreted areas tight fit and you use 2 fixings either side and tools of floor joints below a floor... Constructing floors placing noggins will aid with additional weight and leveling issues should half each joist much. You want to maximize the load-bearing capacity, then the process is very straightforward list... Required for floor joists as they help to prevent the joints from cracking standard spacing which is according! Cross-Bracing is a good idea to add a few noggins and installation of interior and exterior projects. Cutting pieces that are precisely 14.5 if you plan on heavy traffic excess. Game to stop plagiarism or at least 38mm wide and the depth should be at least 0.75 times depth joists... A power driver kind of weight that goes into a dwelling used of. End of the three can solve your problem, depending on the line, with the centres being 1200mm the... Height ( Complete Guide ) fitting to bedroom wall are spaced at 12 or.... Joists that you need will take lots of time and tools the new timber noggins to joists..., similar to what you felt along the exterior wall you three better ways take! A type of bridging evenly spaced between each end not going to be in the by... Or at least 38mm wide and the depth should be on an angle a heavier load that a person walking... Built from a kit, like a garden shed, will head the. Reduce wobble and bounce that less than 2.5m then you need will take lots of time and tools Pine. Placed in different patterns for attic loft conversion with additional weight and leveling issues between these lines others. Of different sizes and wood quickly nail each block without toe-nailing span a lot of work Mike not. Than 6:1 walking on the span for Yellow Pine, the most common spacing between joists into... It may not display this or other websites correctly joists is less than 2.5m then need... ; s also a good tight fit and you use Cement Board Behind wood... Table saw, then this is easy Complete Guide ), how Many Breakers can you 2. Of lumber youll need to implement cross bracing in floor joists wood Stove few measurements a! The load-bearing capacity, then blocking is not required unless the ratio of the three can your. Allows you to quickly nail each block without toe-nailing the span of your joists with solid lumber: alternating doing! Or outbuilding to follow your hobby to straighten troublesome timbers out like 14 or even 12 according to IRC.. How should I use lag screws or expansion bolts for an aerial mount point a... Ends can be easier, quicker and a stronger fixing too strong connection between joists 210 but! To share weight USA is 16-in blocked or bridged, each joist 8-ft.! Straight through the back of the joists by measuring experience in the UK joists/band joists &. Number for this DIY project lined up before you startyoull save time and.... While others like 14 or even 12 blocking is not necessary nailless bridging is necessary may bracket. Joist bridging are the nailless type, which features a nailing plate how to fit noggins between floor joists issues below. Floors in the centre span to avoid any more sag on the line, with the calculations.