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Is bridging really necessary between floor joists. I hear some say yes and others say no. Please send me some thoughts. Thank you
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My thoughts have been sent...
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*Jason, not much else matters except for your local code. Does she or doesn't she bridge? Inspectors seem to rule.
*CABO code requires that you do something when the depth to width ratio exceeds 6-1 (a 2x12) otherwise not necessary. See FHB 117 for my opinion (skip'em). Even when you exceed 6-1 all you have to do is run one strap (1x3) down the center of the span to comply w/ code...And then it's only there to reduce joist twisting.NAHB Research Foundation and Dept. of Agri. determined years ago that to be virtually useless under most circumstances. Skip'em.
*b Bridging's for babies....Did I say that already?J
*Bridging is just another sinister attempt to wipe the spoted owls off the map!tSave the owls!Don't fall for the evil plot layed out by all those squeaky complainers!Blue
*Hot tip guys: Ok, and rookie blind females!The lumber company continues to send bundles of 1x3 for bridging. The concrete guys used to steal it after we would just leave it laying there. Now we use it for roof kickers while we are sheeting the roof!Since I staple every sheet, while I'm laying it, I simply slap a 1x3 down, as I go, and staple the bejeevers out of it (about 7 or 8 staples). I then lay another on top of it, slightly staggering it up, and staple it again. This leaves a tidy little hook for my stapler to hang, and it also holds scrap plywood rather well too!It is light, easy, fast, and abundant! We used to use studs, but they were always in short supply, and we would usually have to take them down, and re-usethem for our punchlist. No more! Send your 5$ to "The booger man,aka blue"Blue
*The CBC requires some type of bridging, blocking or strapping on all residential homes.I use blocking in all cases. The blocking starts and finishes at the rim boards. It must be continuous to work as designed.When there has to be an openning of ducts or pipes, we install a 2x4 on the flat, top and bottom of the joist.Will a house fall apart without bridging, blocking or strapping, of course not.Will bridging, blocking or strapping stop all the squeaks in the floor, probably not.What it will do is give you a more rigid deck if it's done right.
*b Let the kids play with the blocking!!]J
*Gabe, I seriously would tear it out if you installed it in my house! My wife would be happy too, (she's a pyro) as she burned it all in her fire pit!Blue
*Jack and Blue,My wife says I'm only allowed to play with you guys for a hour a day, but she's in the other room thinking that I'm working. WRONG.Remember the other post about what make a good GC and his relationships with his subs.I stand by my method because it makes up for some of the changes for the worst that our industry has had to endure over the past decades.
*What worst are you referring to? Many will also use the stuff, but I dont see how it helps. If it did, why wouldn't it be required on open trusses. Why doesn't the span charts reflect a longer distance allowed with multiple sets of the stuff? squeklessly yours,Blue
*Blue when you are refering to open truss, would the drywall strapping on the underside not count?The span charts have taken into account the wood's natural stiffness in resisting torque. The placement of the strap, block or bridging is as required to maintain that stiffness. It's a lot like the strenght properties of a piece of 2X2 on end.If you cut a short piece, say 1 foot long, put it on a solid surface, balance yourself on top of it and the 2x2 has no problem holding your weight.If the same is done with a 2x2 that is 12 feet long, the piece would snap in a second.Simply because it bowed to snap. If that same piece of wood was prevented from bowing or torquing, it would hold your weight exactly like the 1 foot piece would.The next time you do a joists floor, go underneath with a step ladder and grab the joist from the top and pull down on it with your weight and watch the action of the joist. It will turn as it flexes downward. If you can prevent it from this torquing action you will see that it can hold more weight before flexing.Any additional blocking or whatever would simply be redundency.Hope this helps.
*"Bridging" is required. Otherwise, there would be no other way for Brownie Girl Scouts to proceed to the next level, Juniors. My daughter's "bridging" ceremony is this June. In construction, it causes more problems then it solves. If not required by code, don't use it.
*Blue, Was going to ask you this at the fallfest, but it seems to relate to the topic at hand.Had an inspector tell us this week that we needed to put solid blocking between the floor joist(2x10)were they overlap on top of an interior bearing wall. Never been called on this before.Your thoughts?
*Congratulations on your daughter's achievements.
*All the floor trusses I have used require a permanent lateral brace(2X6 on edge)nailed tightly to the vertical web near the center of the truss(designed for HVAC chases).The floor does seem "weak" prior to installing the laterel bracing,but after it is installed,stiffens the floor dramatically.I assume this would be the main reason for bridging in an "old fashioned 2X" floor system.BTW,I'm not leaning any direction on this one,I believe there may be a place for bridging,but usually some of it gets knocked out anyway by subs,thus defeating the whole purpose.
*Fred, even on the MacMillan silent floor joist system, they require blocking or squash blocks at partitions with any loading.Your inspector's requirements are normal on large spans.
*Gabe, Aware of and follow the detailing for TJI's as you describe.We had 2 simple spans one~15' the other was ~13' overlap was 16"over a 2x4 wall.My original post was wrong we were using 2X12. None of the guys ever recall having to put solid blocking between dimensional lumber joist over a bearing wall. His interpretation of the code would require solid blocking over the steel beam as well. Still curious if thats the norm.
*I'm not familiar with all the codes but can you tell me if you joined the two spans by nailing the joist together at the beam or were they simply overlapped.We always block it but I don't know if it's required on regular wood joists.
*Thats a weird one. Had an inspector want that once. I found out that in the absence of bridging, he wanted the midspan solid blocked to prefent the joist from twisting.He wouldn't allow a few toenails to do the job.I believe you might be able to lay a 2x4 block down, to prevent the bottom from twisting. The top will stay put due to the glue and nails. The 2x4 would be faster if they will accept it.Weird!Blue
*Ahh 2x12! that's a horse of a different color.He might want the blocking to prevent the joist from all leaning over. A row of bridging over the partitions might be acceptable.Bridging is required for 2x12.You mentioned that the lap is 16". I usually limit the overhang on a lap to 1" or less. This prevents "push up" when the joist is flexed downward on the opposite side of the beam. I believe that the rule of thumb is 1/2 the height of the joist.Blue
*Blue, Gabe, Another typo one my part actual open spans were correct overlap ~6"and nailed together. Joist are 16'&14' exterior walls 2x6 interior wall 2x4 sorry for the miss info. The guy's had soild bridging in at mid-span on the joist, it was just over the partion that he wanted it added.I'll talk to the inspector when we get insulation inspection next week would guess your right blue re joist roll. He was a good guy and said he'd check when he was back the next time. Do most of your inspectors work with you on stuff like this? Our's usually do.
*Whose building this house anyways?Most inspectors will work that way if possible.Blue
*Blue, Two story addition one of several jobs we have going on. Wish I could say I framed this one but can't. Have ran into a few inspectors that were off the wall perhaps another thread possibility. Remodeling away in NVA.
*Fred,The last home I built...called for final...Inspector said "That's great Jack, How's life treating you these days....yak yak and then he said I know you do good work...it will arrive in a few days in the mail....I think he was onsite for one inspection....Inspectors come in all types of "dogs" just like the lawyers and of course "us Contractors."
*Gentlemen. For years the NABB--National Association of Homebuilders has tried to have the briudging requirement stricken from the codes. Reasearch by both the NAHB Forest Products Laboratory (FPL) on the effects of bridging on floor stiffness was done with a large floor mockup. The floor was instrumented and subjected to loading, both with and without bridging. There was a difference. But as William James said, "A difference that nakes no difference is no difference." Based on NAHB's and FPL's findings, codes allowed non-bridging. Until recently codes said bridging at midspan was not necessary unless one exceeded the 50 lbs/sq ft DL +LL, or exceeded a joist depth of 12 inches.The concern, obviously, was twisitng of deeper joists.One of the universities in the Canadian Maritime Provinces spent considerable time researching the bridging issue and seems to have solved the problem They recommned running a metal strap directly under the bridging, and securing it to the underside of the floor joists. The metal strapping can be replaced with 1x3 furring, so common in New England ceilings.Homer Hurst formerly of Virginia Polytech found that by running oak strip flooring parallel to the floor joists (glued and nailed) resuylted in a stiffer and stronger floor, because of the composite effect of alternate layser"floor joists, floor sheatjing, oak strip flooring. GeneL.
*On one home we built the engineer maximized the span on a 11 7/8 TJI floor system. We blocked the center with TJI blocks. After the floor was on I noticed there were Squeaks. The squeaks were coming from the blocks. The floor flexed not enough to be noticable but enough to cause the TJI block to loosen on its nails. We removed the blocks that were making the noise.The next house we did we didn't install any blocks at the midspan. The floor was also 11 7/8 tji's. The inpsector called us on the blocks in the area that had the largest span. Had to install about 5o blocks after the electric and plumbing.Now we us Simpson cross bracing. It cost more but we haven't had any noise problems.BlueSwanson 12" speed square works great for cutting the TJI blocks that go under interior bearing walls. Make one mark on the edge and guide the saw with square. I cut the point of my down to about 11 1/2 so that it will work on a rim joist that sits on a wall.
*I can understand the need to have a smaller sqaure sometimes, but not enough to actually carry one all the time. I'm afraid no one has convinced me yet as to their importance. The framing square will remain the square of my choice. And since I don't carry two hammers, I'm not going to carry two squares. Blue
*Blue,I do use a speed square for measuring angles...How do you measure angles with a framing square?J
*I never really measure them, and don't normally need to know them. I know by heart the angles for the pitches, 12/12 = 45, 5/12 = 22.5, etc.I don't know trig, so the actual angle is not important.I cut most jack cuts by eye, never actually tilting the table.The most jacks that I cut are on the layons. Lets say I'm laying a 8/12 onto a 12/12. I make the level mark on the rafter, and then cut it on the line at 90 degrees. I then bevel the cut at 45 degrees by tipping the saw to the approximate bevel by eye. Where else do you need to measure angles on the rough?Blue
*Having aced my way through math in high school I tend to rely on it instead of roof pitch...I could do it the other way and toss the slow square...but not tonight...J
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Is bridging really necessary between floor joists. I hear some say yes and others say no. Please send me some thoughts. Thank you
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The bridging question is one of many most frequently ask questions. We primarily use the CABO 1&2 Family Dwelling Code for residential construction here, we also can use BOCA but it's not as builder friendly. There is no requirement for bridging for floor joists under 2x12's although it may be required by the design professional, but it's really not necessary for typical construction. If anything I found strip bridging more beneficial on shallower members than cross or solid block. It holds the joists in line as they dry and restricts deflection particularly on joists that are maxed. There also is no reqirement for solid blocking over a girder and under bearing partitions. There is a minimum of a 3" overlap or splice when joists rest on a girder. As a side note, bridging and other framing requirements apply to solid wood and for the most part, do not cover the use of TJI's and the like. They are engineered wood products and their use is manufacturer specific. There now is a uniform spec for sizing and use of these products. I believe it's put out by APA, but not sure. Personally I would rather see more nails than waisted lumber. Keith