Help With Roof Issue

Originally Posted By: mlong
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http://www.nachi.org/bbsystem/usrimages/P/P1010013.jpg ]


Thanks.


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Mark Long
Peace of Mind Home Inspections
http://www.pomhi.net

Originally Posted By: lkage
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Mark, I built many homes with porches like that (some engineered, some not) but normally we would lay a 2 x 12 on the flat, perpendicular on top of the trusses, to set the upper porch rafter cut onto. It spreads out the weight of individual rafter loads.


With that said, I don't think I would worry about your photo's setup too much either, but I'm not an engineer.


--
"I have never met a man so ignorant that I couldn't learn something from him."
Galileo Galilei

Originally Posted By: jnosworthy
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Mark,


I have to agree with Larry on the flat 2 x ledger detail offering spread out loads. If it makes you rest any easier, look at all the top chord lumber over pretty closely for any signs of stress, any splitting of grain, loose knots, etc. Look the gusset plates over to convince yourself there is no movement where braces meet chords. Maybe stringline the lower edge of the top chord and compare that measurement to the opposite side of the roof top chord, measured in the same place. Unless their is measureable movment, serious deflection, or signs of stress, I don’t know that I’d recommend anything. If I talked to anybody it might be the guys at the local truss fabricator.


Originally Posted By: mlong
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Thanks for the the input Larry and John. I too have used the 2" x 12" ledger, and have seen it used in situations like this in order to spread out the load, so to speak. And I too thought that something like that should have been done here. My problem is, that I can’t put my hand on any specific rationale for doing that, other than that’s the way I was taught to do it when I was young and was learning to build houses.


My dilemma here, (I hadn't really given the whole story), is that a building contractor was in the attic before me looking at some other issues, and he is the one that originally brought it up, that the point where the porch roof rested on the house roof wasn't adequately supported. I was brought in to render a second opinion. So whatever my opinion turns out to be, I want to be able to give some rationale for it. And if I have to refer to an engineer, I will, but even though it might have been better supported, I really don't think that it's a big deal. I see no evidence of sagging, stress, cracks, etc.

If it does in fact need more support, all it would take, I think, is installing some upright braces from the exterior wall up to each porch rafter to take the weight off of the house roof. It would be a fairly easy and inexpensive fix. But I really don't want to recommend even a simple fix, if in fact there is nothing to really fix. I was hoping to be able to put my hands on some charts, data, or something that would back up my recommendation one way or the other.

Any other thoughts out there?


--
Mark Long
Peace of Mind Home Inspections
http://www.pomhi.net

Originally Posted By: Steven Brewster
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John mentioned contacting a local truss mfger. That’s where I would start. I would have the basic info, span of building, span of porch rafters, type truss, pitch of roof, etc… They should be able to give you the info you need.


Originally Posted By: jonofrey
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mlong wrote:
I see no evidence of sagging, stress, cracks, etc.


This is the key. Nothing to report on really. Tell the client like it is.

mlong wrote:
If it does in fact need more support, all it would take, I think, is installing some upright braces from the exterior wall up to each porch rafter to take the weight off of the house roof. It would be a fairly easy and inexpensive fix. But I really don't want to recommend even a simple fix, if in fact there is nothing to really fix. I was hoping to be able to put my hands on some charts, data, or something that would back up my recommendation one way or the other.

Any other thoughts out there?


Sounds like your operating more in the mode of consultant on this one. Putting myself in your shoes, I would have no problem telling the client that there is no evidence of a problem, but in case your overly concerned, the fix is an easy one such as you've described above. I would hesitate to refer this to a SE.


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Originally Posted By: bking
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I think your location has a major bearing on the difference between borderline and wrong. I do not think trusses are designed for additional point loads such as this and when you add the snow load possible for your area you could have a failure easily.


I don't inspect roof structures for just obvious problems, I look for the correct design to handle worse case (snow) loads. Here in SC we had a recent snow storm that dumped 12 inches at my house and 16 inches about 8 miles away.

I would not recommend a SE but would recommend extra bracing by a licensed contractor familiar with roof structures and snow loads. Also would recommend re-inspection after work is complete.


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www.BAKingHomeInspections.com

Originally Posted By: mcyr
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icon_smile.gif icon_smile.gif


Mark; It is nice to see that you have received good advice here for what your picture indicates.

Larry is correct in saying a 2"x12" laid flat to distribute the load. I would also add that the roof sheathing should have been installed all the way down the rafters to the eave in addition.

John is also correct in talking to a Truss Manufacturer, because obviously, their truss was not designed for this overlay of another roof.

Bruce is correct in possible failure due to snow loads, because the point load as seen in your picture, dose not show additional chords on the truss design to compensate for the additional loading.

The bottom line would be I guess to write it as you see it, and appears you have done that.
Further evaluation is required by a prominent Framing Contractor is advised to assure capacities of roof trusses have not been exceeded.

Good job.

Marcel


Originally Posted By: mlong
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Thanks for all of the input everyone! I believe I’ve got it covered.



Mark Long


Peace of Mind Home Inspections


http://www.pomhi.net

Originally Posted By: pdickerson
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Mark,


Looks like you got it figured out. I agree with the others that the top cord of the truss appears to be improperly point loaded mid-span, which could result in a failure if the roof were to be fully loaded. We had 20" of snow here a few years ago. the next day it started raining at 8:00 AM, and the snow soaked it up like a sponge. It didn't start dripping into the gutters until noon. A lot of roofs in the area collapsed that day.

As a home inspector, I would be hesitant to come in and render a second opinion in a structural issue. It seems to me that if there is a question as to whether or not a structural issue exists in a home, the right person from which to get a second opinion would be a structural specialist (SE or truss designer), not an HI.