Replies

1. 
   MasterCarpenterAce | Jul 11, 2012 08:04pm | #1

   Like this

   Bill you have to be a bit more exact, truss packages are not a complete roof. You cannot epect to be able to set them on and they have valleys and hip blocking. " 80 % of home additions and remodels are done wrong! You have to

   1. Find your center line and snap it clear threw your addition.

   2. Then If the Ridges allign it is simple: Set all your trusses with matchin reveals on either side.

   3. Where the sheathing goes Nail 2x4X16  {at least 12'} every 5"..as you sheet you will love these.

   4. nail rat runs every 6' for ceiling sheathing/gypsum. Nothing like 75 lbs in the air and it dont fit....

   5. Before you even touch the house roof you sheath the bottom row and nail evey 6" it takes a lil longer but if you block the 4'seams you will increase the total streagth of the system. Also 6' minimum Angeld Bracin from your gable wall to the rat run.

   6. Transfer your Ridge from your trusses by running a string line from front of new to point of intersect in existing roof>>>note not once have i said demo the roof....check the weather listen to three different news channels and then make sure you have enough time to frame and sheet and dry in in one day and enough helpers to insure it gets done quick...more hands less time...key to roofing!!!

   7. From there its not rocket science. Asuming you did your job right and have the walls at the correct hieght..and level... then your tails on the trusses will tell you where to start your valley...Hear me out...unless you damn good im going to tell you the easiest way that is right... when you find you fascia point that touches the house. transfer the line to the old roof...from that point to the string line where your ridge goes snap a red perm line ....snap a line 3" away and cut your shingles thereall the way past the rigde to the point where both sides meet " point"

   keeping your line in placethis is where you plywood should plane into..

   8.  Set your Ridge 2x12x? where the ridge meets the truss i recomend plywooding that truss on both sides..typically building code requires you seperat the house and garage with  double 5/8 Gypsom. most people store gasoline in their garge...hmmmm

      ***the plywood triples the strength of the truss. this make so you have a solid hanger placement, with addition blocking underneath as well as the sides build to last"

   9.  where your new ridge meets a wall capable of handling a load add a stiff leg T from the top plate to >>

   10. now that your ridge is secure. begin layout pulling from the trusses

   11.. easist way to frame over a roof is to block from under the seathing on existing but this method is not worthy of a carpenters touch. Take and find you bevel and angle lay it in and check that it will allow 1/2 to plane out with line which is still there!!! if so take 1.5" off the angle and place a 2x10 up the eisting roof where the two meet continue layout to the peek and the rest is a cake walk i would hope...   .

1. 
   MasterCarpenterAce | Jul 11, 2012 08:08pm | #2

   p.s. if they are asking you to buy more standard trusses and cut them do not even think of this not a good idea...whenever you change a truss it loses it stamp for structural unless in your case your fortifiening it with plywood and or gypsom

1. 
   BSzydlo | Jul 11, 2012 09:08pm | #3

   Thanks for your reply

   MasterCarpenterAce,

   Thanks for taking the time to reply.  Maybe I was a little unclear.  The standard trusses I am using are 24', 2" OC with a 4/12 pitch.  The new addition will be attached perpendicular to a detached garage so the main part of the house will not be affected.  The ridge of the new addition will be equal in height to the existing structure forming a T.  Originally I had planned to use the trusses for the main part of the addition but then switch to 2 x sleepers with a ridge board tying the last truss to the existing roof with individual cut rafters from the ridge board down the sleepers.  A friend suggested I go with a manufactured trusses to join the new roof to the old.  Looking at the drawing of the graduated trusses I noticed (1) there is no ridge board, (2)  there is no "lay down" to replicate the sleepers.  I was always under the impression that the purpose of the lay down was to spread the load across the roof surface and to provide for a nailing surface for the sheathing.  

   With the roof trusses I am concerned that the ends to attach to an existing truss but rest on the sheathing.  When discussing this I was told that with the design of the truss it is not important since you can nail the truss along the length of the cross tie that runs along the bottom of the truss.

   Regarding the nailing of the sheathing again I was told that this will not be a factor that a bottom nailing surface is not required with modern trusses.

   Being sort of a perfectionist I do not want to do this with a chance of future failure.  I've seen enough poor construction and replaced enough to know that I want to do it right the first time.

   Am I missing something with the use of trusses over the existing roof or from the advice of various friends?

2. 
   BossHog | Jul 11, 2012 10:12pm | #4

   The type of trusses that go over a perpendicular roof are called "Valley trusses".  There is no need for a "sleeper" of any kind.

   When you stick frame a valley, all the weight from the valley rafters is on the low end of thw boards.  that's why a sleeper is oftn used there- To spread out the load.

   A valley truss typically had verticals abour 4' O.C.  The added verticals spread the load evenly over the roof below.  Hence no need for sleepers.

   If that explanation doesn't make sense let me know and I'll try to find some pictures for ya.

   BTW - I've been designing and selling trusses since 1984.  I don't recommend valley trusses for a couple of reasons.

   First is that since there's only one of each truss type they tend to be expensive. I don't think they're worth it.

   Second is that if you're going over a hand framed roof the picth may not be perfect.  If it isn't, you may have to slide the trusses one way or another to make them plane out.  If you do, that meses up the spacing for your plywood.

1. 
   BSzydlo | Jul 11, 2012 11:09pm | #5

   Thanks for the clarification

   From a cost perspective it appears to be a slightly more if I go the  trusse route but since time is a factor I am thinking it is worth to speed the project along.  I think the total cost for the set would be slightly under $200.  While I have framed a hip roof extension it was not a quick process and the ease of trusses is appealing.  

   If you don't mind I have a few items to clarify:

   1.  If I use the trusses I will not need to nail any type of filler (sleeper) to nail the sheathing to.  The trusses spaced 2' on center are sufficient.

   2.  It is not necessary to reinforce under the ends of the truss as the weight is distributed across the entire span.   I have read of some individuals nailing a 2 x 4 between the existing trusses to support the end of the new truss.

   3.  The roof I am attaching it to was built using trusses so the pitch is consistent.

1. 
   BossHog | Jul 12, 2012 06:29am | #6

   No reinforcement, fillers, or blocking needed. Just nail the valley trusses down and forget it.

   Here's a page with a lot of valley details from our engineering supplier:

   http://www.mitek-us.com/Valley_Details.aspx

1. 
   BSzydlo | Jul 12, 2012 07:07am | #7

   Thanks for the link - it answered all my questions.