I Joists Roofing/blocking?

 
Thread Tools Search this Thread Display Modes
Old 12-24-2008, 09:14 AM   #1
Dan
 
ApgarNJ's Avatar
 
Trade: Remodeling Contractor
Join Date: Apr 2006
Location: Stockton, NJ
Posts: 4,822
Rewards Points: 2,000
Send a message via AIM to ApgarNJ

I Joists Roofing/blocking?


hey guys. we are framing a long shed roof using I joists LP brand. the span is 25' but some of the are 34' long because they tie into another roof. some tie into a wall. all on the same shed roof. no where on the plans does it call for any blocking between I joists. i have only used I joists on floor systems before and we used them in the middle of the floor span using left over Ijoist material as the blocking. instead of metal cross bracing.
the architect says he doesn't think on a roof, the I joists need any kind of cross bracing once they are sheathed. i think differently. that long of span, I think we need blocking like every 12 ft maybe. using either metal cross braces or wooden i joists if we have enough left over pieces.

what do you guys think? necessary or not. we are using 5/8 sheathing on the roof. and the guy is going to sheath the the underside of the i joists with osb 1/2". since it's a wood working shop.
ApgarNJ is offline  

Warning: The topics covered on this site include activities in which there exists the potential for serious injury or death. ContractorTalk.com DOES NOT guarantee the accuracy or completeness of any information contained on this site. Always use proper safety precaution and reference reliable outside sources before attempting any construction or remodeling task!

   
 

Old 12-24-2008, 09:35 AM   #2
Pro
 
Joe Carola's Avatar
 
Trade: Framing Contractor
Join Date: Jun 2004
Location: Caldwell, New Jersey
Posts: 1,568
Rewards Points: 1,000

Re: I Joists Roofing/blocking?


Quote:
Originally Posted by ApgarNJ View Post
hey guys. we are framing a long shed roof using I joists LP brand. the span is 25' but some of the are 34' long because they tie into another roof. some tie into a wall. all on the same shed roof. no where on the plans does it call for any blocking between I joists. i have only used I joists on floor systems before and we used them in the middle of the floor span using left over Ijoist material as the blocking. instead of metal cross bracing.
the architect says he doesn't think on a roof, the I joists need any kind of cross bracing once they are sheathed. i think differently. that long of span, I think we need blocking like every 12 ft maybe. using either metal cross braces or wooden i joists if we have enough left over pieces.

what do you guys think? necessary or not. we are using 5/8 sheathing on the roof. and the guy is going to sheath the the underside of the i joists with osb 1/2". since it's a wood working shop.
Dan,

What brand I-joist are you using? Download their installation guide. Here's TJI's installation guide.

http://www.ilevel.com/literature/TJ-4001.pdf

__________________
Joe Carola
Joe Carola is offline  
Old 12-24-2008, 12:16 PM   #3
Dan
 
ApgarNJ's Avatar
 
Trade: Remodeling Contractor
Join Date: Apr 2006
Location: Stockton, NJ
Posts: 4,822
Rewards Points: 2,000
Send a message via AIM to ApgarNJ

Re: I Joists Roofing/blocking?


LP brand. i did download their install. i don't see any mention of blocking. just seems like it should be done though. maybe i'm just too used to framing with dimensional lumber.
ApgarNJ is offline  
Old 12-24-2008, 12:26 PM   #4
Pro
 
Joe Carola's Avatar
 
Trade: Framing Contractor
Join Date: Jun 2004
Location: Caldwell, New Jersey
Posts: 1,568
Rewards Points: 1,000

Re: I Joists Roofing/blocking?


Quote:
Originally Posted by ApgarNJ View Post
LP brand. i did download their install. i don't see any mention of blocking. just seems like it should be done though. maybe i'm just too used to framing with dimensional lumber.
I've used them a couple times for rafters and never used blocking or metal bridging. I-joists completely different compared to dimensional. If it's not on the plans or in their installation, don't do it. Check out the blocking for the floors, you can't just toenail the i-joist blocks into the joists.
__________________
Joe Carola
Joe Carola is offline  
Old 12-24-2008, 12:28 PM   #5
Pro
 
orson's Avatar
 
Trade: Kitchen & Bath
Join Date: Nov 2007
Location: Millersville, PA
Posts: 1,346
Rewards Points: 500

Re: I Joists Roofing/blocking?


I have only ever seen blocking called for when the I joist is being used for rafters and the flange is cut where it is sitting on the top plate. In this case you need either blocking or x bracing as specced by manufacturer.

You do not need blocking when the full flange is resting flat on a wall.
orson is offline  
Old 12-24-2008, 01:06 PM   #6
Member
 
billderboots's Avatar
 
Trade: Building Contractor
Join Date: Mar 2008
Posts: 83
Rewards Points: 75

Re: I Joists Roofing/blocking?


I use the I-joists all the time for about 6 years now and up untill a year ago I always used the metal bridging. The Rep came out and chewed me out for it. Seems that may void the silent floor feature. I thought it definately helped with strength and deflection, so we no longer use them. Rep claims you dont need them.
billderboots is offline  
Old 12-24-2008, 01:08 PM   #7
Pro
 
Tom M's Avatar
 
Trade: GC/ Interior & Exterior Remodeling
Join Date: Jan 2007
Location: Bergen County, NJ
Posts: 4,232
Rewards Points: 3,574

Re: I Joists Roofing/blocking?


Orson that seat flange better not ever be cut short of the plate. I dont see a need for blocking either since the point is to prevent rotation on either side of the rafter you accomplish that with the sheathing.
Joe When you framed the floors did you have to put filler between the blocks?
Tom M is offline  
Old 12-24-2008, 01:28 PM   #8
Former Framer
 
wallmaxx's Avatar
 
Trade: 89% framing master
Join Date: Jun 2007
Location: WA State
Posts: 2,944
Rewards Points: 4,796

Re: I Joists Roofing/blocking?


Rather than blocking...I have had success with tension bridging.

__________________
--
just me.

just sayin'.
wallmaxx is online now  
Old 12-24-2008, 01:55 PM   #9
Pro
 
Joe Carola's Avatar
 
Trade: Framing Contractor
Join Date: Jun 2004
Location: Caldwell, New Jersey
Posts: 1,568
Rewards Points: 1,000

Re: I Joists Roofing/blocking?


Quote:
Originally Posted by wallmaxx View Post
Rather than blocking...I have had success with tension bridging.

Are you using them for rafters, floors, or both?
__________________
Joe Carola
Joe Carola is offline  
Old 12-24-2008, 02:12 PM   #10
Former Framer
 
wallmaxx's Avatar
 
Trade: 89% framing master
Join Date: Jun 2007
Location: WA State
Posts: 2,944
Rewards Points: 4,796

Re: I Joists Roofing/blocking?


I've never had to use I-joists as rafters...I was just thinking for lateral stiffness this should work. I've used them for joists only...sawn lumber and "I".

Solid blocking is always more labor and potentially more squeaks from all the nails. I stopped using bridging blocks entirely when I talked to the engineer of one of our apartment projects who told me bridging didn't do much to strengthen of stiffen a floor system unless it receives a HUGE point load midspan. He said they were good at creating future remodel work when they start to squeak.

As far as the OP, my thought is that this is a sloped floor system. If he's worried about joist/rafter roll...this would help. Not really necessary though. If you are plywooding both sides...you create a boxed system. Strong like bull.
__________________
--
just me.

just sayin'.

Last edited by wallmaxx; 12-24-2008 at 02:16 PM.
wallmaxx is online now  
Old 12-24-2008, 02:16 PM   #11
Pro
 
Joe Carola's Avatar
 
Trade: Framing Contractor
Join Date: Jun 2004
Location: Caldwell, New Jersey
Posts: 1,568
Rewards Points: 1,000

Re: I Joists Roofing/blocking?


Quote:
Originally Posted by tom m View Post
Joe When you framed the floors did you have to put filler between the blocks?
I've only had a couple plans spec metal bridging and that's what I use. Other than that, I never use anything mid-span with I-joists. If you use blocks, you have to follow the installation guide and use fillers like they show.
__________________
Joe Carola
Joe Carola is offline  
Old 12-24-2008, 02:24 PM   #12
Former Framer
 
wallmaxx's Avatar
 
Trade: 89% framing master
Join Date: Jun 2007
Location: WA State
Posts: 2,944
Rewards Points: 4,796

Re: I Joists Roofing/blocking?


Like Joe said, all manufacturer's have literature for bridging if it is required.

Now, if you want to make your roof really "strong" as far as lateral shear (if that would ever be a concern) you can frame is as a structural diaphragm. It wouldn't help in the ability to negate vertical loads like snow...but it will increase the overall strength of the system by incorporating more of the plywood strength into the system by giving you complete nailing surface for the entire plywood edge of each sheet of plywood.

Install blocking like this every 4 feet where your plywood seams will be. Glue and nail everything 4" o.c.

Okay...I'll get off the overkill soap box now.

__________________
--
just me.

just sayin'.

Last edited by wallmaxx; 12-24-2008 at 04:00 PM.
wallmaxx is online now  
Old 12-24-2008, 02:51 PM   #13
Pro
 
Joe Carola's Avatar
 
Trade: Framing Contractor
Join Date: Jun 2004
Location: Caldwell, New Jersey
Posts: 1,568
Rewards Points: 1,000

Re: I Joists Roofing/blocking?


Quote:
Originally Posted by tom m View Post
Joe When you framed the floors did you have to put filler between the blocks?
Scroll down to where it says Floor Details page 9 to PB1. It shows you what to do when using I-joists as blocks.

http://www.ilevel.com/literature/TJ-4001.pdf
__________________
Joe Carola
Joe Carola is offline  
Old 12-24-2008, 02:52 PM   #14
Dan
 
ApgarNJ's Avatar
 
Trade: Remodeling Contractor
Join Date: Apr 2006
Location: Stockton, NJ
Posts: 4,822
Rewards Points: 2,000
Send a message via AIM to ApgarNJ

Re: I Joists Roofing/blocking?


i have used those metal straps as well wallmaxx. which is what I would use for this roof. I may put them in the middle of the span as we are laying the sheets of plywood down. a lot of times i just tack the top as we sheath and then fasten the bottom once we are all dried in.

i used the i joist as blocks a while ago and it was my first time using them. i used I joist material as the block in the center. and staggered them so i could get a nail through it. may not be like they recommended but that's what I did and haven't had any issues. architects never show these things. and i wasn't sure I had to do them. not sure why you can't toenail a i joist block into the main floor or roof joists? the top and bottom are either 2x3 or 2x4 fir so why not?
anyways. i'll be sure to put those filler blocks at the top where we hung from a ledger board on the wall.
ApgarNJ is offline  
Old 12-24-2008, 03:00 PM   #15
Pro
 
Joe Carola's Avatar
 
Trade: Framing Contractor
Join Date: Jun 2004
Location: Caldwell, New Jersey
Posts: 1,568
Rewards Points: 1,000

Re: I Joists Roofing/blocking?


Quote:
Originally Posted by ApgarNJ View Post

i used the i joist as blocks a while ago and it was my first time using them. i used I joist material as the block in the center. and staggered them so i could get a nail through it. may not be like they recommended but that's what I did and haven't had any issues. architects never show these things. and i wasn't sure I had to do them. not sure why you can't toenail a i joist block into the main floor or roof joists? the top and bottom are either 2x3 or 2x4 fir so why not?
anyways. i'll be sure to put those filler blocks at the top where we hung from a ledger board on the wall.
There has to be a reason maybe structurally why. If you do it like you did and you do have a problem, you will be at fault for not following the installation guide. Follow what they say and you will have no problems.
__________________
Joe Carola
Joe Carola is offline  
Old 12-24-2008, 03:54 PM   #16
Dan
 
ApgarNJ's Avatar
 
Trade: Remodeling Contractor
Join Date: Apr 2006
Location: Stockton, NJ
Posts: 4,822
Rewards Points: 2,000
Send a message via AIM to ApgarNJ

Re: I Joists Roofing/blocking?


i will in the future. i'll admit it was my first time using them and never bothered to ask about an installation guide. but i have since that particular job. span wasn't very far. 17 feet. no interior walls.
ApgarNJ is offline  
Old 12-25-2008, 05:03 PM   #17
Former Framer
 
wallmaxx's Avatar
 
Trade: 89% framing master
Join Date: Jun 2007
Location: WA State
Posts: 2,944
Rewards Points: 4,796

Re: I Joists Roofing/blocking?


Our floor system was spec'd like this once.
__________________
--
just me.

just sayin'.
wallmaxx is online now  
Old 12-28-2008, 09:57 AM   #18
Pro
 
borat_borat1950's Avatar
 
Trade: framing
Join Date: Dec 2008
Location: Arkansas
Posts: 118
Rewards Points: 75

Re: I Joists Roofing/blocking?


Quote:
Originally Posted by wallmaxx View Post
Our floor system was spec'd like this once.
That's the one I always use, And BCI specs the smae thing, block three spaces in at mid points and beams, stops lateral movement.
borat_borat1950 is offline  
Old 12-28-2008, 10:07 AM   #19
Instructor, ex-contractor
 
critter's Avatar
 
Trade: Construction trades Instructor
Join Date: Nov 2008
Location: Northumberland, Pa
Posts: 86
Rewards Points: 75

Re: I Joists Roofing/blocking?


Floor systems experience point loading. Bridging has two purposes. One is to prevent deflection of the lower edge of a joist. The other is to share point loads over to the next joist or two each side of the one being loaded. So, bridging a floor improves its rigidity - just be wise with nailing and adhesive to avoid squeaks - or be especially careful that steel bridging is nailed to create a tensioned intall. Roof live loads are generally uniform, making bridging of any type unneccesary, especially with the OSB sheathing on the underside.
critter is offline  
Old 12-28-2008, 10:44 AM   #20
Pro
 
borat_borat1950's Avatar
 
Trade: framing
Join Date: Dec 2008
Location: Arkansas
Posts: 118
Rewards Points: 75

Re: I Joists Roofing/blocking?


Quote:
Originally Posted by critter View Post
Floor systems experience point loading. Bridging has two purposes. One is to prevent deflection of the lower edge of a joist. The other is to share point loads over to the next joist or two each side of the one being loaded. So, bridging a floor improves its rigidity - just be wise with nailing and adhesive to avoid squeaks - or be especially careful that steel bridging is nailed to create a tensioned intall. Roof live loads are generally uniform, making bridging of any type unneccesary, especially with the OSB sheathing on the underside.
I never knew that bridging an I-Joist prevented deflection, I always thought it was walls and micro-lams that prevented deflection. How much can I over span the manfactures recommended spans if I use this bridging?? 5' or 6' maybe? Just curious?

borat_borat1950 is offline  


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Blocking I joists Morning Wood General Discussion 8 12-10-2008 07:08 PM
I joists for roofing, questions ApgarNJ Framing 18 11-11-2008 09:38 PM
Replacing joists in rowhouse Philly Dude Framing 3 10-16-2008 06:24 PM
Dealing with Floor Joists dcapone Low Voltage 0 08-18-2008 02:45 AM
Framing Roof Joists for Addition when top Plate is not Level personalt Framing 3 07-20-2007 06:52 AM

Join Now... It's Fast and FREE!

I am a professional contractor
I am a DIY Homeowner
Drywall Talk is for
PROFESSIONAL CONTRACTORS ONLY!

At DrywallTalk.com we cater exlusivly to professional contractors who make their living as a contractor. Knowing that many homeowners and DIYers are looking for a community to call home, we've created www.DIYChatroom.com DIY Chatroom is full of helpful advices and perfect for DIY homeowners.

Redirecing in 10 seconds
No Thanks
terms of service

Already Have an Account?