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Old 09-18-2013, 06:13 PM   #16
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Roof truss tie plate


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Originally Posted by GBrackins View Post
yes a gable end wall truss have vertical members usually at 16" o.c. for attachment of wall sheathing.

if you go with outriggers (2x members that go back to the 2nd truss) then the gable endwall truss is shorter than the inboard truss
How do you figure at what size to make the drop truss rafter? I assume it would 3.5" shorter in height?

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Old 09-18-2013, 06:26 PM   #17
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Roof truss tie plate


if using a 2x4 then it would be 3.5" shorter as measured perpendicular to the roof pitch
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Old 09-18-2013, 07:46 PM   #18
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Roof truss tie plate


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if using a 2x4 then it would be 3.5" shorter as measured perpendicular to the roof pitch
So im using a 7/12 pitch do I just make each top cord 1.5" shorter in length?
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Old 09-18-2013, 10:54 PM   #19
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Roof truss tie plate


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if using a 2x4 then it would be 3.5" shorter as measured perpendicular to the roof pitch
Is it ok to use mending plates that you can get at home depot/lowes for the truss connections for a shed?
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Old 09-18-2013, 11:03 PM   #20
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Roof truss tie plate


I do not know what mending plates are. they may work fine but I can't say, hopefully someone will answer that question for you
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Old 09-19-2013, 01:56 PM   #21
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Roof truss tie plate


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Originally Posted by detroittigerfan View Post
Is it ok to use mending plates that you can get at home depot/lowes for the truss connections for a shed?
Like everything else in this biz, these things have multiple names: "mending plates", "gang nail plates"

The Simpson ones I've seen at the box stores warn they should not be used for assembling trusses.

The thing with these plates is that they're tricky to install. Truss fabricators use an industrial-strength press to sink them into the wood in one quick and smooth motion. Installing these things on the field without compromising the plate and connection is no small challenge. Banging away at various points with a hammer is going to mangle the thing. Eventually you might sink it in, but it won't look good. But that's the least of your worries. The metal's strength is likely compromised as it's beat up, and some of the teeth may bend, to boot.

If it's a small plate, you might get away with using some sort of clamp. But then did you use too small a plate to pull this off, and thus compromise the design strength of the truss?

I would personally avoid using a plate and go with a plywood gusset on both sides of the joint, with a 3" nailing pattern.

But that's just me.
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Old 09-19-2013, 03:42 PM   #22
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Roof truss tie plate


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there are two ways of doing an extended rake, one as shown on page 43 of this link

in my area most are ladder framed (2x4's or 2x6 so they look like a ladder) and attached directly to the gable end wall studs.

either way works
GBrackins, the ladder frame approach is a bit frightening to me. You basically have a cantilever with zero counter support (rule of thumb is 2:1). As if that wasn't precarious enough, the cantilever is hovering 8' to 20' above grade, and is part of a platform that is sometimes walked on. So, the "either way works" description scares me a little. I'd like to throw some criteria into the mix:

use the ladder frame approach only
(a) if the extension is minimal (certainly no more than 1' from the gable wall)
(b) if the outside run of the ladder frame is supported at both ends. At the top, it should be fastened to the extended ridge board/beam. At the bottom, supported by the sub-fascia.
(c) in climates with little or no snow loads
(d) with roof pitches exceeding 3/12

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Old 09-19-2013, 03:50 PM   #23
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Like everything else in this biz, these things have multiple names: "mending plates", "gang nail plates"

The Simpson ones I've seen at the box stores warn they should not be used for assembling trusses.

The thing with these plates is that they're tricky to install. Truss fabricators use an industrial-strength press to sink them into the wood in one quick and smooth motion. Installing these things on the field without compromising the plate and connection is no small challenge. Banging away at various points with a hammer is going to mangle the thing. Eventually you might sink it in, but it won't look good. But that's the least of your worries. The metal's strength is likely compromised as it's beat up, and some of the teeth may bend, to boot.

If it's a small plate, you might get away with using some sort of clamp. But then did you use too small a plate to pull this off, and thus compromise the design strength of the truss?

I would personally avoid using a plate and go with a plywood gusset on both sides of the joint, with a 3" nailing pattern.

But that's just me.
What about a mending plate that has predrilled holes in it for nailing?
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Old 09-19-2013, 03:55 PM   #24
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What about a mending plate that has predrilled holes in it for nailing?
That's perfectly fine. Lower profile than plywood gussets, much less work, and may perform better, too.
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Old 09-19-2013, 03:59 PM   #25
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That's perfectly fine. Lower profile than plywood gussets, much less work, and may perform better, too.
In your opinion wouldn't you think a metal plate would be stronger than plywood gussets? Oh and how much of the plate should cover where the vertical stud meets top chord and where bottom chord meets top, etc?
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Old 09-19-2013, 04:14 PM   #26
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Roof truss tie plate


Depends on the thickness of the metal. Downside to metal is it's a lot harder to customize. I'll cut plywood over metal any day ;-) But if you find plates that are the size you need, and you're comfortable with the thickness, go for it.

As for size and placement, that's not something I or anyone here can easily answer. There is no prescriptive code for putting together an arbitrary truss (not that I know of, anyway). Lots of data and math goes into truss design. It's not for the faint of heart. One option is to follow someone else's lead in a comparable project. For example, you might want to go into a box store model shed of your comparable design and take some notes, maybe some pics. They almost all contain roof trusses.
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Old 09-20-2013, 12:32 AM   #27
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Roof truss tie plate


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Originally Posted by cortell View Post
GBrackins, the ladder frame approach is a bit frightening to me. You basically have a cantilever with zero counter support (rule of thumb is 2:1). As if that wasn't precarious enough, the cantilever is hovering 8' to 20' above grade, and is part of a platform that is sometimes walked on. So, the "either way works" description scares me a little. I'd like to throw some criteria into the mix:

use the ladder frame approach only
(a) if the extension is minimal (certainly no more than 1' from the gable wall)
(b) if the outside run of the ladder frame is supported at both ends. At the top, it should be fastened to the extended ridge board/beam. At the bottom, supported by the sub-fascia.
(c) in climates with little or no snow loads
(d) with roof pitches exceeding 3/12
Thank you for expressing your concerns, however it truly is not so frightening.

Ladder framed extended rakes have been installed in my area for over a 100 years. Our ground snow load is 30 psf. Ridges are commonly around 33' to 35' here. Roof pitches range from 6/12 to over 12/12 commonly and our basic wind speed is 110 mph.

Like a lot of things we have not seen before there is always concern. When I first moved here builders were concern in using LVL's and I-joists. Now they are common place. Plumbers swore that PEX tubing was from the devil.

This is allowed under the American Wood Council's Guide to Wood Construction in High Wind Areas (110 mph) as shown in Figures 15 & 16 on page 15 http://awc.org/pdf/WFCM_110-B-Guide.pdf

also note these are allowed at no more than 12". You can actually go up to 24" when using the AWC's Wood Frame Construction Manual.

I agree that outriggers are a preferred way, however builders in my area have been using this technique for a long time with success and since it is allowed it is difficult to get an old dog to learn new tricks sometimes.
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Last edited by GBrackins; 09-20-2013 at 12:35 AM.
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Old 09-20-2013, 08:32 AM   #28
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Roof truss tie plate


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Thank you for expressing your concerns, however it truly is not so frightening.
[snip]
GB, if the assembly is supported at the top by an extended ridge beam/board and at the bottom by the sub-fascia, then indeed it is not alarming at all. In that case, the lookout members are merely blocking between two rafters...just so happens one of the rafters is located beyond the footprint of the structure. However, this was not detailed or implied in your description, nor in that awc document. As always, the devil is in the details. If the ladder frame is supported only by the screws fastened into gable wall studs, then that seems precarious to me. But who am I to question a practice that's been around for a century.
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Old 09-20-2013, 05:55 PM   #29
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Hi,

I have a small dilemma. Am building a small playhouse with trusses and using plates to connect the joints and chords. After there installed and I go to sheathe the end gables do I just avoid nailing in the area of the plates and work around it?
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Old 09-20-2013, 07:18 PM   #30
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Roof truss tie plate


How thick are these plates your using? The ones from the truss company can usually be penetrated with a nail.

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