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  1. #1
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    Default Take a look at these truss /rafter support

    Check this out and let me know if you have ever seen this. Manufactured trusses supporting rafters where the rafters were notched. I don't believe any engineer would approve this.
    Your thoughts?

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  2. #2
    Garry Blankenship's Avatar
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    Default Re: Take a look at these truss /rafter support

    Never have seen anything like that. It looks like a few of the mfg, truss components are like 3x4s, is that the case (?). The trusses ultimately are carrying the roof load, but those notched rafters, (?), look to be raising the roof base / OSB maybe an inch. That effectively is a 1" x 1 1/2" skip sheathing on roughly 2' centers. I do not see that surviving a good snow load or point load like an ex-pro football offensive lineman / inspector. I'd make it clear that I am not a structural engineer, question the application and leave it to the client to accept or investigate.


  3. #3
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    Default Re: Take a look at these truss /rafter support

    those look like the hip roof section, typically manufacturers here have the 2x4's installed perpendicular to the trusses on top laid flat but then you have to pull the hip in so it does not make the soffit on that end larger. these guys installed like rafters, you have to see what the truss company states to lock in the hip trusses

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    Building Forensic Specialist LLC

  4. #4
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    Default Re: Take a look at these truss /rafter support

    Gary,
    That 3X4 you see actually is 2/x4 with a 1X4 reinforcing. The buyer was a little uneasy with it and walked away. We don't get much snow load here in the Dallas area but it still concerns me with this set up. Here's another photo of the opposite side arrangement.

    Thanks everyone for the feedback.

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  5. #5
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    Default Re: Take a look at these truss /rafter support

    Somewhere, there is a plan that shows how the roof was supposed to be framed up.
    The hip end of a trussed roof often ends up looking a bit flaky, but the designers will explain that the actual load per sq inch is minimal.

    The truncated trusses are load bearing and the short 2X4's are usually just nailers. They are laid flat in many cases. What Joseph said.

    John Kogel, RHI, BC HI Lic #47455
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  6. #6
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    Default Re: Take a look at these truss /rafter support

    What on earth is going on with that grid-pattern framing in the 1st pic on the right-hand side? I can't see that having much structural integrity.

    "It takes a big man to cry. It takes an even bigger man to laugh at that man". - Jack Handey

  7. #7
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    Default Re: Take a look at these truss /rafter support

    Donnie,
    your lap isn't big enough to have this sitting in it ;~))
    let the engineer of record or other p.e. issue that letter stating all clear
    or maybe the owner has the original plan, probably not

    badair http://www.adairinspection.com Garland, TX 75042 TREC # 4563
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  8. #8
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    Default Re: Take a look at these truss /rafter support

    check records for permit and framing sign off.


  9. #9
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    Default Re: Take a look at these truss /rafter support

    I think this could be a lot of over reacting without know the design of the truss and the engineers intent. If a buyer walked because of it, it may have been unnessesary. It is a hip roof and the so called rafters don't appear to me to be much more than a purlin of sorts.... the load is being carried by the trusses. Not much of a snow load in Texas. Hunt down the truss drawings and design to verify.

    Randy Gordon, construction
    Michigan Building Inspector/Plan Reviewer

  10. #10
    TCattell's Avatar
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    Thumbs up Re: Take a look at these truss /rafter support

    Quote Originally Posted by Door Guy View Post
    I think this could be a lot of over reacting without know the design of the truss and the engineers intent. If a buyer walked because of it, it may have been unnessesary. It is a hip roof and the so called rafters don't appear to me to be much more than a purlin of sorts.... the load is being carried by the trusses. Not much of a snow load in Texas. Hunt down the truss drawings and design to verify.


    I Agree!


  11. #11
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    Default Re: Take a look at these truss /rafter support

    The trusses fit where the engineers designed them. Rafters can be nailed to other rafters. The framer who put notches in those boards did it because he wanted consistency. The fact is nobody likes (especially the framers) how hip trusses are designed (because of all the blocking) but you got to work with what they give you. Some of the newer designs on the trusses like that are actually stepped down on the top chord so that the 2x's lay flat on top which is much stronger and easier to work with.


  12. #12
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    Default Re: Take a look at these truss /rafter support

    Sure is funky-looking. Can't blame the buyer for walking. And I suspect wind loading in Texas is always more of a factor than snow loading. If the seller is really serious about selling the place, he/she needs to invest in the services of a licensed P.E., who could evaluate the entire attic's framing system and sign off on it if everything is found to be structurally adequate.


  13. #13
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    Default Re: Take a look at these truss /rafter support

    I agree with Garry that the notched "rafters" offer no appreciable structural support other than that equivalent to skipped sheathing. That could be remedied by adding joist hangers at each location to support the bottom of each notched rafter. Also, I don't think the trusses were manufactured under any quality control process as required by the IBC (IBC Section 2303.4). Check the trusses for stamps that indicate the manufacturer name and "TPI 1" to verify.

    Thom Huggett, PE, SE, CBO

  14. #14
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    Default Re: Take a look at these truss /rafter support

    Quote Originally Posted by Door Guy View Post
    I think this could be a lot of over reacting without know the design of the truss and the engineers intent. If a buyer walked because of it, it may have been unnessesary. It is a hip roof and the so called rafters don't appear to me to be much more than a purlin of sorts.... the load is being carried by the trusses. Not much of a snow load in Texas. Hunt down the truss drawings and design to verify.
    Anything said about any truss installation could be said to be 'over reacting without knowing the design of the trusses and the engineer's intent', however, that is not, to my knowledge, an acceptable way to notch and lay rafters/framing nor to attach said rafters/framing to the trusses as that is basically 'end notching' and there are limitations of such. Those could split at the notch, thus those rafters/framing members may only be equivalent to 1x2, if even that.

    Let the engineer make the call - not much cost for a whole lot of relief (if the engineer says no problem) or by-passed grief (if the engineer ways WTF?). Either way, the client knows the answer.

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  15. #15
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    Default Re: Take a look at these truss /rafter support

    Quote Originally Posted by Ray Thornburg View Post
    The trusses fit where the engineers designed them. Rafters can be nailed to other rafters. The framer who put notches in those boards did it because he wanted consistency. The fact is nobody likes (especially the framers) how hip trusses are designed (because of all the blocking) but you got to work with what they give you. Some of the newer designs on the trusses like that are actually stepped down on the top chord so that the 2x's lay flat on top which is much stronger and easier to work with.
    It appears to me that they were dropped 1.5 inches, but the framer didn't lay them down and nail them on top, but ran them vertical and notched them. Is it a problem?, doubtful it my eyes, but I'm not qualified to make the call...

    Randy Gordon, construction
    Michigan Building Inspector/Plan Reviewer

  16. #16
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    Default Re: Take a look at these truss /rafter support

    http://www.alpeng.com/images/stories/pdfs/BGT_BOOK.pdf


    I belive this is a hip set that uses "hip cats" as seen on page 13 of this guide the midwest hip is what it is referred to.


  17. #17
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    Default Re: Take a look at these truss /rafter support

    But, they didn't cut the trusses.

    The above statements are expressed solely as my opinion and in all probability will conflict with someone else's.
    Stu, Fredericksburg VA

  18. #18

    Default Re: Take a look at these truss /rafter support

    Quote Originally Posted by paul hardy View Post
    http://www.alpeng.com/images/stories/pdfs/BGT_BOOK.pdf


    I believe this is a hip set that uses "hip cats" as seen on page 13 of this guide the mid-west hip is what it is referred to.
    Paul
    Good resource, thanks.

    I have installed many of that type of configured roof assembly. We generally put it together on the ground and craned it in place. In the photos it looks as if the purlin frame is missing.

    Before purlin frames were available we blocked in at 24" O.C. This was the way it was done and still very strong. I don't' have any pics of us lifting the trusses in on assembly but do have of a roof demo.
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  19. #19
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    Default Re: Take a look at these truss /rafter support

    The framer put the notches there simply so he could line them up with the roof angle easier .....they are not meant to be structural but they do hold up the plywood at that point. The framer could have just put a plumb cut on those blocks but it's hard to gauge when you're two stories up in the air. The trusses that are designed so that the 2x lays on top have a notch at the hip so there's no way to switch it up....plus there's the layout issue. If you move the truss the hip doesn't line up.


  20. #20
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    Default Re: Take a look at these truss /rafter support

    Quote Originally Posted by Ray Thornburg View Post
    The framer put the notches there simply so he could line them up with the roof angle easier .....they are not meant to be structural but they do hold up the plywood at that point. The framer could have just put a plumb cut on those blocks but it's hard to gauge when you're two stories up in the air. The trusses that are designed so that the 2x lays on top have a notch at the hip so there's no way to switch it up....plus there's the layout issue. If you move the truss the hip doesn't line up.
    Ray,

    That framing is structural. That framing is not there to just "hold up the plywood at that point", that framing is there to support the roof sheathing at the required support spacing the entire length of those framing members.

    *IF* those framing members had been installed as "The framer could have just put a plumb cut on those blocks", then the truss top chords would serve as the required support for the roof sheathing, provided the truss spacing is within the span rating of the plywood.

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  21. #21
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    Default Re: Take a look at these truss /rafter support

    That's what I said .....trusses hold up sheathing ......and so does the blocking.....but the blocking only holds up the sheathing......well maybe a little lateral support....that's the way they designed it......if there is a better way to lay plywood on those cheap hip trusses I'de like to hear it.....otherwise leave the poor framer alone.... he's lucky they gave him enough 2x4's to block it with.


  22. #22
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    Default Re: Take a look at these truss /rafter support

    Quote Originally Posted by Ray Thornburg View Post
    That's what I said .....trusses hold up sheathing ......and so does the blocking.....but the blocking only holds up the sheathing......well maybe a little lateral support....that's the way they designed it......if there is a better way to lay plywood on those cheap hip trusses I'de like to hear it.....otherwise leave the poor framer alone.... he's lucky they gave him enough 2x4's to block it with.
    The problem is that he no longer has 2x4s to hold up the sheathing, at most he as 2x2, and with those ends notched like that, they may well split such that there is even less than 2x2 remaining ... what he effectively has is the sheathing holding up that framing ... and that is the opposite of what it was design to do ... provided that was the design.

    Typically, in a design like that, the 2x4s are laid flatwise on top of the truss top chords, and that is likely the intended design.

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  23. #23
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    Default Re: Take a look at these truss /rafter support

    Quote Originally Posted by Jerry Peck View Post
    The problem is that he no longer has 2x4s to hold up the sheathing, at most he as 2x2, and with those ends notched like that, they may well split such that there is even less than 2x2 remaining ... what he effectively has is the sheathing holding up that framing ... and that is the opposite of what it was design to do ... provided that was the design.

    Typically, in a design like that, the 2x4s are laid flatwise on top of the truss top chords, and that is likely the intended design.
    Like I said ....you can't get the two different truss designs mixed up because there is a specific layout and the hip would not line up if you slid the truss over enough to accommodate the thickness of a 2x.....those kind of trusses have a dog eared at the hip and the top cord is dropped the proper thickness for the 2x. So blocking it like he did was his only option. Blocking is a lot more work so if he could have done it the other way he would have. I say let's blame the engineer who designed it.... but for some reason engineers always come out smelling like a rose huh......


  24. #24

    Default Re: Take a look at these truss /rafter support

    Ray
    It look as if the purlin truss is missing The notched out blocking is raised above the trusses enough that it looks like the framer could have laid the 2x's on top of the trusses flat.

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    Default Re: Take a look at these truss /rafter support

    Quote Originally Posted by Mark Parlee View Post
    Ray
    It look as if the purlin truss is missing The notched out blocking is raised above the trusses enough that it looks like the framer could have laid the 2x's on top of the trusses flat.
    It only looks that way Mark.....the roof looks to be fairly steep... a 12/12 would have 1.5" on the high side and 0" on the low side height above the truss for instance. The top chord of those trusses would have been 2 1/8" lower measured vertically from the plane of the roof to the top of the top chord on the low side for a 12/12 for instance. That's almost 4 1/4" on the side we're looking at had the trusses been designed that way. The roof looks to be at least an 8 pitch so that's a pretty big drop anyway you look at it. Does that make sense?


  26. #26
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    Default Re: Take a look at these truss /rafter support

    I believe this is what you would find if you had a cross section of the connection. The 2x4 should just be blocking supporting the sheathing but it should be also nailed to the truss properly (I only see one nail).

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    Last edited by paul hardy; 06-26-2012 at 09:42 AM. Reason: fix grammar

  27. #27

    Default Re: Take a look at these truss /rafter support

    Ray
    In looking back at the pictures I see that is a 2x4 block not a 2x6. I thought the framer had notched a 2x6 and left material in the top side to make up for the flat 2x framing.
    These are just blocks with a pitch cut between the trusses and the framer left a little tail that went over the top of the truss to zero.
    I think that is what you were trying to tell me.

    This block in method is one that was used for years, no joist hangers needed. We just cut the mini rafters and nailed them between the trusses. No problems with code we had the drawing packet that came with the trusses and it was stamped by the truss companies engineer.

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  28. #28
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    Default Re: Take a look at these truss /rafter support

    Quote Originally Posted by Ray Thornburg View Post
    It only looks that way Mark.....the roof looks to be fairly steep... a 12/12 would have 1.5" on the high side and 0" on the low side height above the truss for instance. The top chord of those trusses would have been 2 1/8" lower measured vertically from the plane of the roof to the top of the top chord on the low side for a 12/12 for instance. That's almost 4 1/4" on the side we're looking at had the trusses been designed that way. The roof looks to be at least an 8 pitch so that's a pretty big drop anyway you look at it. Does that make sense?
    Sorry....I have to correct myself after thinking about it.....12/12 top chord would drop 3" if it was designed to be nailed on top...I was thinking about the LOR but you get my point.


  29. #29

    Default Re: Take a look at these truss /rafter support

    Paul you posted as I was replying.

    That is exactly how we did it but did not notch in the material over the lower truss, we just left the bottom edge high in plane. As Ray noted it would be 1.5" high if a 12/12 and 1" high if an 8/12.
    These boards were end nailed through the trusses and that was all that was required.

    Mark Parlee
    The Building Consultant www.thebuildingconsultant.com
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  30. #30
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    Default Re: Take a look at these truss /rafter support

    Quote Originally Posted by paul hardy View Post
    I believe this is what you should find if you had a cross section of the connection. The 2x4 is should just blocking supporting the sheathing but should be nailed to the truss properly (one see one nail).
    Good drawing Paul....thanks...


  31. #31
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    Default Re: Take a look at these truss /rafter support

    As has been said this hip set was designed to be framed in with small rafters between the trusses. Normally not notched (birdsmouthed) over the truss but is acceptable. Been framing for thirty five years this way. Nothing wrong here.


  32. #32
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    Default Re: Take a look at these truss /rafter support

    It appears from the photos that the short rafer blocking are not nailed properly to the truss top cord. They should have some 3 to 4 toe nails into the trusses top cord. The roof sheathig has to resist, uplift, gravity loads, and lateral loads. All of these loads are tranfered through the connections to the top cord of the truss.

    I believe a PE needs to evaluate this and provide a fix.


  33. #33
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    Default Re: Take a look at these truss /rafter support

    probably face nailed....or nails on the other side where you can't see.....trust me....nobody's going to want to walk on those things if they're not nailed.


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