Replies

1. 
   Longhair | May 21, 2004 12:48am | #1

   we only use them on the horizontal dont think i have ever seen it used on the vertical but hey who knows

2. 
   WayneL5 | May 21, 2004 12:56am | #2

   You should space the trusses to exact dimensions, that is, if it calls for 24" center to center spacing, you should do just that.

   The little metal things you call spacers may be edge supports.  Are they shaped like an H?  If so, they are only used on horizontal joints.  All the vertical joints must land on a rafter.  Their purpose is to clip the plywood on both sides of a horizontal joint together so you don't have one piece flapping independently from the one above or below.  It makes nails go in a bit better and the roof less bouncy when you walk on it, and less chance of nails popping.

3. 
   hammer1 | May 21, 2004 02:11am | #3

   Sheathing plywood today is generally sized for spacing. It says so right on the sheet. The metal clips are not used for spacing on the ends, they are used to support the horizontal edge between the trusses. Trusses are placed at 24" OC so the unsupported plywood from truss to truss can move up and down. The clips help them move together. When doing your layout for the trusses the first mark from the outside of the framing, not the sheathing is either 23 1/4" or 24 3/4", your choice. The X is placed on the 24" side of the mark. After the first mark you can move your tape and mark every 24". This is how you get the sheets to land half way to the trusses. The space between sheets as they meet on the truss is done by eye usually, but as you suspect too big a space is cumulative and you can lose the center on a long run. When I frame long walls I will sometimes start the first layout mark at 23". The first sheets are not dead center but they gain as you go. We also mark the centers on the leading edge of the plywood as we go to keep the trusses straight. I don't nail the gable ends until last, that way I can go down on the ground or sight up the gable to make sure they look straight. If the framing is 16" OC or the sheathing is T&G we don't use clips. Of course you can cut a sheet if you lose your centers. On some framing jobs you can see where an extra stud has been added due to poor layout, you don't want to add an extra truss though. Do you know how to brace and space trusses as you are putting them up? People get hurt and projects are destroyed by improper or inadequate bracing. Just another heads up. If this a weekend project don't completely sheath one side and leave the other for next week. Heavy wind can turn your roof into a kite, better to place a couple of rows each side.

1. 
   AndyEngel | May 21, 2004 03:19am | #4

   Although I've seen the writing, I've never measured a panel that was truly sized for spacing. The only solution I know is to butt them tight, then run a saw kerf down the joint.

   AndyArguing with a Breaktimer is like mud-wrestling a pig -- Sooner or later you find out the pig loves it.

4. 
   Sphere | May 21, 2004 03:38am | #5

   don't delete it, you got it!  Now explain to him about the rake lookouts..step down trusses or notch for a flat 2x4?

   yur on a roll..can't give up now

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5. 
   JimJ | May 21, 2004 08:36pm | #6

   Thanks to all who replied.

   I didn't know the little 'H' edge supports were for Horizontal support, not vertical.

   Since I'm doing this project TOTALLY alone, I had planned to layout the Truss spacing as everyone described. But to keep them straight when the crane lifts them into place, I had planned to nail a little metal bracket to the plate top to guide the truss into place; then nail a cross piece to hold them vertical until the roof sheeting goes over. I know I have to put a 'catwalk' across the bottom chords and some form of 'X' bracing between the trusses to support them vertically. If the Trusses are 'X' braced, won't they hold their 24" center spacing? Once braced, they would be hard to move - or should they be braced AFTER the roofing is put on so that they CAN be moved a little to keep them aligned with the plywood? From Butch's description, I deduce that he is allowing 1-1/2" overhang past the bottom end of the Truss to accommodate a facia board and the 'snap' line is to allow for small variations at the ends of the Trusses (?). I'm laying metal roofing over the plywood and it is recommended that it extend 1 " past the plywood edge. This, plus a drip strip (?) will keep the water away.

   I appreciate all of the feedback. What the heck is 'rake lookouts' or 'stepdown trusses' or 'notch for a flat 2x4s' ?

   
   

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   Edited 5/21/2004 1:55 pm ET by J-J

   
   

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   Edited 5/21/2004 1:56 pm ET by J-J

1. 
   CapnMac | May 21, 2004 09:39pm | #7

   What the heck is 'rake lookouts' or 'stepdown trusses'

   Rake Lookouts are "stub" rafters perpendicular to a gable wall that support an overhanging roof over the gable end.  They are used when the roof overhangs more than just the fascia.  They get a bit more impressive with Greene&Greene-sized overhangs in the 3-4' range.  Then, you need a cantillevered (or "ladder") rake rafters.

   Step Down Trusses are for hip-gabled roofs.  They occur "after" the end of the ridge beam.  Thus, they have a 'flat' across the top, instead of coming to a point.  They can be very labor saving, as they eliminate the need for traditional hip rafters and roof framing.Occupational hazard of my occupation not being around (sorry Bubba)

2. 
   WayneL5 | May 22, 2004 01:06am | #8

   You do have to x-brace as soon as the trusses are up.  Otherwise, they are unstable, and can all just fall over like a stack of dominoes.

   It really happens.  One day I drove by a building where they had nearly completed placing all the trusses for a roof.  Next time I drove by they were all toppled over in pieces on the floor.

   For safety, you have to cross brace before the plywood goes on.  Once the plywood is on, the system is stable and you can remove the braces.  In high wind areas special bracing is needed for the gable ends.

1. 
   tenpenny | May 22, 2004 02:00am | #9

   I'd be careful saying "Once the plywood is on, the system is stable and you can remove the braces." with Boss Hog around.  He is the expert on trusses and bracing; just wait till he shows up.

1. 
   Snort | May 22, 2004 02:10am | #10

   Well just in case Boss doesn't show up for a while, after the plywood is on, you can permanently brace your trusses...crosswise,bottom chords, gables and else whatever else your truss man specs. Wayne musta been thinkin' of concrete forms<G> Don't worry, we can fix that later!

   Edited 5/21/2004 7:11 pm ET by bucksnort billy

2. 
   Sphere | May 22, 2004 03:54am | #12

   most places I've been building ( about 4 states) bracing is CODE required..with or with out sheathing..

   I diagonal brace the underside of the top chords AFTER sheathing..ceiling chords need a gable to gable runner both sides..1/3 span.

   Use a T dead man on the first gable ( allow for gable sheathing thicness when ya plumb the truss)

   look outs are for supporting the rake subfascia/fascia..do not be tempted to just let it hang, unless the overhang is less than 10 inches..even then a nailer for soffit might be handy.

   throw 1x3 temp braces ABOVE the 46.5 area..as you set the trusses TACK into them..this will allow you to stabilize the structure prior to actually sheathing..

   it takes two ( at least) to do a proper and safe erection..no joke.

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3. 
   Sasquatch | May 22, 2004 02:28am | #11

   Before you proceed, find a local framer who will help you get started.  For about $150.00, you should be able to find someone who can be with you throughout the process.  This is not something you should be doing alone for the first time.  You will save more than the labor costs you.  It sounds like you have a good start on the textbook side of the project; however, you need someone with experience to save time ($ crane and operator $), prevent a loss of material, avoid personal injury, and place trusses and braces correctly.  Go to some local job sites and ask the folks working there if they know someone who would be willing to help you set some trusses.  Anyone who has done this before, even if they are not the best, will be better than you doing the project alone.  Heed this advice!

4. 
   RalphWicklund | May 22, 2004 04:06am | #13

   As well as providing the technical package for the trusses, your truss supplier should also be including a safety and installation, which includes bracing, package, which normally accompanies the delivery.

   Your structural engineer should also verify and specify attachments as well as bracing. Most plans (at least the ones I do) are required to have the permanent bracing included, however........

   The following attachments - HIB-91 cover pic and a few select drawings should help you understand. It would be a good idea to get a copy of the HIB-91. The package that comes with the trusses contains copies of portions of this booklet (or should).

   Proper bracing, starting with the first truss set, will save you many headaches.

   I also recommend that you get ALL your bracing and blocking and uplift connectors in place before you haul up the first sheet of ply. It's literally a real PITA to have to crawl around under the lid if you don't.