Tgi Framing

knucklehead · 10-28-2009, 09:09 PM

I thought it was TJI ?

**loneframer** · 10-28-2009, 09:29 PM

Quote:

Originally Posted by neolitic

I know that before we put bridging
in at my son's house a little Jack Russell
running across the floor sounded like
freaking a Gene Crupa solo, and would
bounce the needle on the turntable.

What ever the tests say, I was
in a basement once to nail off the tails
of the western bridging, when they rolled
a cart of drywall through the room.
I could see the gaps open and close
as the joist twisted a bit at the bottom.

Lone, I guess you and I will
just keep on bridgin' along!

Neo, I'm coming up on 25 years of in the field experience with long spans, builder grade material and many different opinions on bridging. I know for a fact that before the bottom of wood bridging is fastened, you can hold a straight edge on the bottom of the joists, in the center of the span and when someone stands on top of a single joist it will push the straight edge down below the other joists. (deflection) After the bridging is fastened, the same anomoly does not take place. With metal strap bridging, under the same circumstances, the joist will still deflect on it's own. I have done this experiment in front of a reputable builder to argue my point on wood bridging and he was sold on it. He stopped using metal and still uses wood to this day. For those who don't believe wood X-bridging is beneficial, that is your right. I personally won't build a floor without it and I will never use metal strap again. Drive in metal bridging is valid, but I prefer wood above all else.
Guess it's just me and you Neo.

**loneframer** · 10-28-2009, 09:30 PM

Quote:

Originally Posted by knucklehead

I thought it was TJI ?

Yup, TJ=Trus-Joist

**KentWhitten** · 10-28-2009, 09:33 PM

Quote:

Originally Posted by knucklehead

I thought it was TJI ?

Actually, it's simply I-joists. TJI stands for Truss Joist International.

A W Smith · 10-28-2009, 09:52 PM

Quote:

Originally Posted by loneframer

Neo, I'm coming up on 25 years of in the field experience with long spans, builder grade material and many different opinions on bridging. I know for a fact that before the bottom of wood bridging is fastened, you can hold a straight edge on the bottom of the joists, in the center of the span and when someone stands on top of a single joist it will push the straight edge down below the other joists. (deflection) After the bridging is fastened, the same anomoly does not take place. With metal strap bridging, under the same circumstances, the joist will still deflect on it's own. I have done this experiment in front of a reputable builder to argue my point on wood bridging and he was sold on it. He stopped using metal and still uses wood to this day. For those who don't believe wood X-bridging is beneficial, that is your right. I personally won't build a floor without it and I will never use metal strap again. Drive in metal bridging is valid, but I prefer wood above all else.
Guess it's just me and you Neo.

I have to agree with you. The importance of cross bridging cannot be understated. I worked for a builder 30 years ago who would argue the point that solid bridging was superior to cross bridging. I disagree, The nails can simply pull out of the end grain of solid bridging causing individual joist defection and annoying squeaks. Cross bridging however acts as a continuous truss distributing point loads to adjacent joists. Think of the tops of cross bridging as legs to a sawhorse pinching the top of the joist during load. what is unfortunate with TJIs is theres little practical way to install wood cross bridging. and add to the fact that every TJI joist is identical in design strength and resonance which can cause a floor to act in resonance like a drum skin. Lumber however with its varying density, moisture content capacity, and weight per joist member can actually dampen resonance. I helped a childhood friend of mine who was a builder build his own house about 28 years ago. He used TJIs throughout but in my opinion they were a little undersized as he acted as his own architect. the town had him get an engineer to run and certify calculations for the floors. I can remember a small Christmas get together he had there. He had this little dog must have weighed perhaps 12 or 15 pounds. I was shocked to see the dog trot across his living room floor and we could feel the floor bounce under our feet. Me and him just laughed.

**loneframer** · 10-28-2009, 10:05 PM

Quote:

Originally Posted by A W Smith

I have to agree with you. The importance of cross bridging cannot be understated. I worked for a builder 30 years ago who would argue the point that solid bridging was superior to cross bridging. I disagree, The nails can simply pull out of the end grain of solid bridging causing individual joist defection and annoying squeaks. Cross bridging however acts as a continuous truss distributing point loads to adjacent joists. Think of the tops of cross bridging as legs to a sawhorse pinching the top of the joist during load. what is unfortunate with TJIs is theres little practical way to install wood cross bridging. and add to the fact that every TJI joist is identical in design strength and resonance which can cause a floor to act in resonance like a drum skin. Lumber however with its varying density, moisture content capacity, and weight per joist member can actually dampen resonance. I helped a childhood friend of mine who was a builder build his own house about 28 years ago. He used TJIs throughout but in my opinion they were a little undersized as he acted as his own architect. the town had him get an engineer to run and certify calculations for the floors. I can remember a small Christmas get together he had there. He had this little dog must have weighed perhaps 12 or 15 pounds. I was shocked to see the dog trot across his living room floor and we could feel the floor bounce under our feet. Me and him just laughed.

Al, I always install wood X-bridging on TJIs. I use 7/16 crown staples. The bridging needs to be cut to almost exact length to allow enough meat on the flanges for stapling. The staples prevent delamination of the LVL flanges and hold surprisingly well.

72chevy4x4 · 10-28-2009, 10:11 PM

seems we've taken a turn to discussing cross bracing...just today I was thinking about using a solid piece of dimesnional lumber cut at an angle and nailed in-so the block would be say for instance a 15 1/2" block beveled on both sides then nailed in the 14 1/2" joist bay. Would that not be sufficient? Reason I ask is because after a floor system is installed it would seem difficult to install the top of cross bracing (correct/incorrect?)

interesting job I'm on-3 story apartments where severe deflection has been resulted from overspaned dimensional lumber (19' spans 12" joists at 12"OC w/ 1.5" of gypcrete). anyhow, one of the units had cross bracing in the kitchen and the joists were nice and straight...the other unit had no crossbracing in the kitchen and the joists were out of plumb about 1/2" in 12". when the joists twist they lose strengh...hopefully a PE will back me up on this statement.

**loneframer** · 10-28-2009, 10:25 PM

Quote:

Originally Posted by 72chevy4x4

seems we've taken a turn to discussing cross bracing...just today I was thinking about using a solid piece of dimesnional lumber cut at an angle and nailed in-so the block would be say for instance a 15 1/2" block beveled on both sides then nailed in the 14 1/2" joist bay. Would that not be sufficient? Reason I ask is because after a floor system is installed it would seem difficult to install the top of cross bracing (correct/incorrect?)

interesting job I'm on-3 story apartments where severe deflection has been resulted from overspaned dimensional lumber (19' spans 12" joists at 12"OC w/ 1.5" of gypcrete). anyhow, one of the units had cross bracing in the kitchen and the joists were nice and straight...the other unit had no crossbracing in the kitchen and the joists were out of plumb about 1/2" in 12". when the joists twist they lose strengh...hopefully a PE will back me up on this statement.

I'm no engineer, but I agree that a joist is strongest when it is held vertical. I also believe that bridging unifies the floor and makes for a better assembly overall.

Timuhler · 10-28-2009, 10:44 PM

Quote:

Originally Posted by loneframer

I'm no engineer, but I agree that a joist is strongest when it is held vertical. I also believe that bridging unifies the floor and makes for a better assembly overall.

Seems logical to me. I'll do some research on this. What I wonder is if there really is a practical difference between briding and blocking. Assuming the blocking is installed in a straight line and nailed properly, why would it act differently than bridging?

Timuhler · 10-28-2009, 10:52 PM

Here is something http://www.astm.org/DATABASE.CART/WORKITEMS/WK24358.htm

http://www.apawood.org/pdfs/managed/...TOKEN=56997938

**loneframer** · 10-28-2009, 10:52 PM

Quote:

Originally Posted by Timuhler

Seems logical to me. I'll do some research on this. What I wonder is if there really is a practical difference between briding and blocking. Assuming the blocking is installed in a straight line and nailed properly, why would it act differently than bridging?

I've done both. I gave up on solid blocking because of cupped joists and shrinkage. They have developed squeeks as a result. X-bridging on the other hand only contacts the joists at top and bottom, eliminating ill fitting connections. Also, with conventional lumber, there is a certain amount of shrinkage. If the bridging is fastened before shrinkage occurs, they will actually tighten up as part of the process. I have seen first hand that as the lumber shrinks, the bridging will actually force a small S shaped curve in the bottom of the joist from the tightening effect.

Timuhler · 10-28-2009, 10:57 PM

Quote:

Originally Posted by loneframer

I've done both. I gave up on solid blocking because of cupped joists and shrinkage. They have developed squeeks as a result. X-bridging on the other hand only contacts the joists at top and bottom, eliminating ill fitting connections. Also, with conventional lumber, there is a certain amount of shrinkage. If the bridging is fastened before shrinkage occurs, they will actually tighten up as part of the process. I have seen first hand that as the lumber shrinks, the bridging will actually force a small S shaped curve in the bottom of the joist from the tightening effect.

lumber shrinks? Our lumber here in WA is very dry

Just look at the Doppler image to see how dry we are

Found this quote using Bing, but don't really want to register to get his info.

I agree, check with the i-joist manufacturer first.

As a consultant engineer, I have fixed a lot of bouncy floors.

One of the solutions that I recommend to my clients is an engineered wood bridging product called IBS 2000.

Having tried many remedies such as full depth i-joist blocking, lumber type blocking or full depth plywood backers, I have found that the IBS 2000 is the best solution.

It is premanufactured to fit any depth and spacing and is very easy to install.

The manufacturer also has a free software program that will help you predict how the floor will feel before and after the IBS 2000 is used.

PE, Washington state

http://boards.hgtvpro.com/eve/forums...1/m/3041095843

**loneframer** · 10-28-2009, 11:05 PM

Quote:

Originally Posted by Timuhler

lumber shrinks? Our lumber here in WA is very dry

Just look at the Doppler image to see how dry we are

Looks like your all wet Tim.

We used to get GRN 2x10s at 9 5/8. Gone back to basements and they were 9 1/4 max. Some smaller. We see mostly S-Dry now, due in part to a major problem with fungus in the GRN lumber. S-dry will still stabilize at about 3/16 less than dimension at delivery on a 2x10.

Timuhler · 10-28-2009, 11:09 PM

Check this out http://www.ilevel.com/roofs/pres/slide/player.html

Timuhler · 10-28-2009, 11:26 PM

http://www.builder.hw.net/walls-and-...o-feature.aspx

"Wind Worthy
A home's wall and roofing design and construction method, if undertaken properly, ultimately creates a shell that is stronger than the sum of its parts, when it comes to load resistance. Here again, fasteners and adhesives play a key role. Experts at the NAHB Research Center observed the following about the lateral pressures exerted by strong winds:

One-story buildings are less vulnerable to wind damage than two- or three-story buildings.
Hip roofs typically perform better than gable-end roofs.
Moderate roof slopes perform best (4:12 to 6:12) in terms of roof uplift.
For composite shingles, six nails per shingle are recommended, not the typical four nails.
Window openings should be protected to avoid pressure changes inside the home in high-wind situations.Floors: Secret Strength
Studies by the NAHB Research Center and others have found that modern floor systems often test out two to three times as strong as individual joists, because all of the structural components are joined together via nails and adhesives. This construction technique—particularly the addition of adhesives—has been shown to create a floor system that reduces the bend in any single joist by up to 60 percent.

Quote:

Another interesting finding was that neither cross bracing nor bridging adds significantly to the load-bearing strength of dimensional lumber joists (2x6- to 2x12-inch). Other floor systems have not yet been similarly tested"

http://www.awc.org/pdf/TR05.pdf check page 18

**loneframer** · 10-28-2009, 11:27 PM

Quote:

Originally Posted by Timuhler

Check this out http://www.ilevel.com/roofs/pres/slide/player.html

Watched the whole video. That is nice technology.

Premarked crowns?

A W Smith · 10-28-2009, 11:56 PM

Quote:

Another interesting finding was that neither cross bracing nor bridging adds significantly to the load-bearing strength of dimensional lumber joists (2x6- to 2x12-inch). Other floor systems have not yet been similarly tested"

I don't think anyone here is claiming that the load capacity of the floor will be increased by adding bridging. But the overall performance of the flooring system as a whole will improve with cross bridging due to distribution of loads across joists.

Timuhler · 10-29-2009, 12:43 AM

Quote:

Originally Posted by A W Smith

I don't think anyone here is claiming that the load capacity of the floor will be increased by adding bridging. But the overall performance of the flooring system as a whole will improve with cross bridging due to distribution of loads across joists.

I think one of the references talks about vibration not being affected or not affected much from blocking or cross bridging. Also, I thought that cross bridging was mentioned as a way to keep the floor stiff over long distances.

**loneframer** · 10-29-2009, 06:28 AM

Quote:

Originally Posted by Timuhler

I think one of the references talks about vibration not being affected or not affected much from blocking or cross bridging. Also, I thought that cross bridging was mentioned as a way to keep the floor stiff over long distances.

I recommend "the bounce test". I do it on nearly every floor. Set the tops of the bridging, deck the floor and take a flying leep in the center of the floor. Next, go fasten the bottoms and take the leap again. There is always a noticable difference in the "feel" of the floor. Whether it be resonance, harmonics or whatever, something changes for the better.

So the debate continues.......

Timuhler · 10-29-2009, 09:20 AM

Quote:

Originally Posted by loneframer

I recommend "the bounce test". I do it on nearly every floor. Set the tops of the bridging, deck the floor and take a flying leep in the center of the floor. Next, go fasten the bottoms and take the leap again. There is always a noticable difference in the "feel" of the floor. Whether it be resonance, harmonics or whatever, something changes for the better.

So the debate continues.......

I'm not debating this subject. I get what you are saying and I have a hard time understanding how cross bridging or blocking (done right) doesn't help.

I took a class at JLC LIVE a few years back and the teacher said that when joists are spaced 16"oc and sheathed, that because they are acting as a unit with the joist on either side, that you are actually 15% stronger.

It seems to me to be logical that blocking would help keep the floor a little stiffer, but the data evidently show that up to and including 2x12, it isn't statistically significant.

What I wonder is if the cross bridging benefit you are seeing would also be there after the drywall is installed on the underside of the joists. In other words, you are feeling with the bridging what you'd feel anyway if the drywall was on. Therefore it isn't worth doing? I don't know. I'm going to email our engineer and see what he says.

10-28-2009, 09:09 PM	#41
knucklehead View Profile knucklehead Pro Send Message Follow Blogs (0) Threads (1,922) Photos (0) Reviews (0) Projects (0) Toolbox (0) View All Activity Pro Trade: Framing,Remodeling,General Contractor Join Date: Mar 2009 Location: Kansas City Posts: 1,922	Re: Tgi Framing I thought it was TJI ?

10-28-2009, 10:11 PM	#47
72chevy4x4 View Profile 72chevy4x4 Contractor Send Message Follow Blogs (0) Threads (2,434) Photos (0) Reviews (0) Projects (0) Toolbox (0) View All Activity Contractor Trade: Remodeling & Home Additions Join Date: Sep 2006 Location: Delaware Posts: 2,434	Re: Tgi Framing seems we've taken a turn to discussing cross bracing...just today I was thinking about using a solid piece of dimesnional lumber cut at an angle and nailed in-so the block would be say for instance a 15 1/2" block beveled on both sides then nailed in the 14 1/2" joist bay. Would that not be sufficient? Reason I ask is because after a floor system is installed it would seem difficult to install the top of cross bracing (correct/incorrect?) interesting job I'm on-3 story apartments where severe deflection has been resulted from overspaned dimensional lumber (19' spans 12" joists at 12"OC w/ 1.5" of gypcrete). anyhow, one of the units had cross bracing in the kitchen and the joists were nice and straight...the other unit had no crossbracing in the kitchen and the joists were out of plumb about 1/2" in 12". when the joists twist they lose strengh...hopefully a PE will back me up on this statement.

10-28-2009, 10:52 PM	#50
Timuhler View Profile Timuhler Pro Send Message Follow Blogs (0) Threads (711) Photos (0) Reviews (0) Projects (0) Toolbox (0) View All Activity Pro Trade: Framer Join Date: Mar 2006 Location: Port Orchard, WA Posts: 711	Re: Tgi Framing Here is something http://www.astm.org/DATABASE.CART/WORKITEMS/WK24358.htm http://www.apawood.org/pdfs/managed/...TOKEN=56997938 __________________ http://picasaweb.google.com/TimothyUhler www.pioneerbuildersonline.com https://plus.google.com/u/0/photos/1...0542215/albums

10-28-2009, 11:09 PM	#54
Timuhler View Profile Timuhler Pro Send Message Follow Blogs (0) Threads (711) Photos (0) Reviews (0) Projects (0) Toolbox (0) View All Activity Pro Trade: Framer Join Date: Mar 2006 Location: Port Orchard, WA Posts: 711	Re: Tgi Framing Check this out http://www.ilevel.com/roofs/pres/slide/player.html __________________ http://picasaweb.google.com/TimothyUhler www.pioneerbuildersonline.com https://plus.google.com/u/0/photos/1...0542215/albums

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