If you are building to code which is the bare minimum at L/360 and no blocking or bridging required, go right ahead. My floor will have blocking or bridging.
If you are building a floor framing that is L/500 or more and leave it out, there might not be any worries. Very few frame floors on residential to these limits.
Do as you wish, this 45 year builder will do what is required to provide a good floor system. I don’t take shortcuts to please the pocket book or because a piece of paper says it is not required.
Marcel, we are on the same page as far as not designing or building to minimum standards. I often use more stringent criteria for designs, including the deflection provisions. But don’t fool yourself into thinking that bridging will noticeably increase the strength of floor framing or reduce deflections, because it doesn’t. Blocking is a little better than bridging, and what I specify/recommend at 8’ max centers, but not because it significantly increases the strength.
You are better off putting that into upsizing the subfloor sheathing, with better glue-and-screw attachments, and with enough screws you get a substantial increase in floor strength and stiffness thru composite action between the joists and subfloor. The following APA & FPL guides have some good info on strength and stiffness of floors, but the second one gets a bit technical.
But a lack of floor joist bridging just isn’t an issue or defect that needs correction by a contractor for a home inspector looking at typical floor framing any way ya slice it …
Thanks for that information Robert, I saved those links for my own use.
I guess being an old mule explains why floor bridging has always been in the picture, but I clearly understand the engineering lingo about the T-Beams. Same principal as the shear studs on a steel beam and deck for a 5" concrete floor. Cambered beams are expensive and they always revert to flat beams and shears studs. Been in Commercial Building for a long time.
Just never related concrete to the wood floor systems of today for residential building.
But in any case, not all contractors glue and nail the floor sheathing. This has only occurred in the past few years up here.
The days of the diagonal board sheathing and 3/4" underlayment like I used to do is quite gone and wish I knew it only added 10% stiffness to the floor system back then. But we did have bridging.
I guess what I am saying is that, one has to evaluate the structure installation and know if it is to today’s standard or not.
I would most likely call for the lack of bridging if no evidence of structural adhesive is observed, type of sheathing and the age of the building.
It has not been many years up here yet that they have been using the modern method of glue and nails.
I very well remember the diagonal flooring sheathing with T&G sheathing and particle board sub-flooring. I nailed everything by hand. But what a ridged floor. Better than the one’s today. :mrgreen:
Its a very common misconception (particularly among old school builders) that bridging adds appreciable strength and stiffness to floor framing. Sometimes it’s hard to get past that if you were taught to do it that way, and then always did it that way.
Funny thing is I had an old school builder in a home inspection field training class yesterday where we were reviewing framing issues. He pointed to an area where wood bridging had been knocked out for a gas pipe and said “isn’t that a problem, cause it’s gonna weaken the floor?”
After I recovered from coffee shooting out of my nose, I told him it wasn’t an issue and pointed to another one with two small nails thru a split tapered end and asked “how much weight is being transfered to the adjacent joist there” … he stared at it for about a half hour before the light bulb when on, and he realized it really wasn’t an issue …
Meaning it adds next to nothing compared to the strength of a typical floor joist, and is not even worth calculating. Would you really be concerned about the added strength of two 6d nails thru a split tapered end of an old 1x3 piece of wood? Your kidding, right …
If you are looking for confirmation from an industry recognized source (and not some internet yahoo), here is a quote from the 2000 Residential Structural Design Guide by NAHB & HUD …
And “negligible” does mean the values are so small they are not even figured into the floor strength or stiffness (it is neglected). I guess the guy who wrote that renovation article didn’t get the memo … :roll:
Bottom line … missing or incomplete bridging is NOT an issue even worth mentioning on a home inspection …
In 35 years of building (as a carpenter- later as a general contractor) I never heard of any floor system failing because it lacked anti-rotational devices like the bridging or midspan blocks discussed here. I can say from experience that one or the other device should definitely be installed if you want a floor to squeak. Forget glue… it won’t help.
I agree … there is a potential for floor squeaks anywhere there is wood to wood contact without both glue and screws.
The newer adhesives are a lot better … local builders all swear by them. Combine that with screws and you have a really solid squeak-free install. I see it done wrong sometimes where the builder puts down adhesive on too many joists at once, and it starts to set up … which can actually increase the likelihood of floor squeaks.
Not sure what you are referring to as that link to APA TN-C468N talks about bridging possibly causing squeaks, particularly if some load is transfered to the bridging (yes, a negligible amount can be transfered) and it’s not securely nailed.
Then ya have a home movie clip of Bubba building his own house where he “got my two by tens” with some of dem dare simpson bridging … and of course ya have to “tack it with some nails” in order to get a “pretty tight floor system”. Here is a clip of that same guy calculating how “tight” it’s gonna be … http://www.youtube.com/watch?v=oldOh_R9nws&feature=mfu_in_order&list=UL … OMG I must be completely wrong …
What is the quote and page from the AFPA details guide are you referring to? I only see a reference to bridging on Page 7, which talks about installing that if a joist depth-thickness ratio exceeds 6.
