Originally Posted By: dbush
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Still Structure
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Dave Bush
MAB Member
"LIFE'S TOUGH, WEAR A HELMET"
Still Structure
"LIFE'S TOUGH, WEAR A HELMET"
Originally Posted By: pdacey
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Depending on the situation, there is more than one possible answer.
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Slainte!
Patrick Dacey
swi@satx.rr.com
TREC # 6636
www.southwestinspections.com
Originally Posted By: jpope
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Jeff Pope
JPI Home Inspection Service
“At JPI, we’ll help you look better”
(661) 212-0738
Originally Posted By: Guest
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There’s a “best answer” and it has to do with wall spread and roof sag.
Originally Posted By: pdacey
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There are two “best” answers, depending on the orientation of the rafters to the floor joists.
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Slainte!
Patrick Dacey
swi@satx.rr.com
TREC # 6636
www.southwestinspections.com
Originally Posted By: rmoore
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On a structure without ceiling joists, such as a detached garage, my first concern would be wall spread and therefore the bottom makes the most sense mechanically. On a normally framed house where the ceiling joists are already acting as collar ties I would suggest any additional ones be towards the top to “tie” the rafters to the ridge board or each other.
Tough question as it stands. Wouldn't want to see this on an exam without a better description of the framing methods and structure involved.
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Richard Moore
Rest Assured Inspection Services
Seattle, WA
www.rainspect.com
Originally Posted By: dbush
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Because this is a sticky question, I went to a PE to get the answer. Thanks Rob. Attached is his answer. This question has been seen as written on a couple of exams.
Maybe a better short answer would be that it depends on the framing, which is why it's so sticky as there is really not enough information to adequately answer the question. But I think there is a "best" answer.
For conventionally framed roofs (with ceiling joists or metal strap ties), the collar ties could be installed up higher, like 2/3 the way up, to not only help stabilize the framing, but also help keep the rafters attached to the ridge plate. But these are not really needed, or used with conventional framing these days, and the position is not really critical. Plus most people would probably think of collar ties as relating to cathedral ceilings.
For cathedral ceilings (how people typically think of applying collar ties) they should be installed as low as possible, because as they are moved up a larger roof rafter and heavier connection is needed. Typically the rafter sizes and connections are not adequate for cathedral ceilings with only collar ties installed up high, which can result in sagging ridge lines and deflected roof framing.
Therefore, I think the "best" answer would be as low as possible down near the bottom.
That sounds a little better ...
Robert O'Connor
Eagle Engineering ?
Eagle Eye Inspections ?
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Dave Bush
MAB Member
"LIFE'S TOUGH, WEAR A HELMET"
Originally Posted By: roconnor
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Richard hit the “nail” right on the head …
Very sticky question boys and girls, and even when I read the question I did a double take and had to really think about what I thought a "best" answer would be.
I can see why most answered up high, since that is usually where you will find them and it would help the rafter to ridge plate attachment. But I dont think thats the "best" location without knowing what the framing is.
I think Chad gave a pretty good hint and is on the same page as me ...
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Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong