# Cathedral ceiling



## MT323 (Nov 28, 2017)

Where in the irc can i find information on spanning of the ridge beam in a cathedral ceiling? For example in section R802.3.1 it says only that if ceiling joists are not provided the ridge should be supported by a wall or girder designed in accordance with accepted engineering practice.


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## cda (Nov 28, 2017)

Welcome?

So is this house in the Republic of Latvia??

May be a little hard to give a good answer.

Do you have a web link to the residential code used by the Republic of Latvia???


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## steveray (Nov 28, 2017)

LVL or engineered lumber company literature....You won't find it in the IRC


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## Pcinspector1 (Nov 28, 2017)

The WFCM (Wood Frame Construction Manual) has ridge beam capacity requirements for interior center bearing roof and ceiling, you'll need the snow load to use the table 2.16, engineering is advisable, you'll need fastener information and bearing requirements at the beams ends.


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## mark handler (Nov 28, 2017)

Accepted Engineering Practices consist of proven engineering methods, procedures, and practices that provide appropriate, cost-effective, and well-documented solutions to meet requirements and compliance with applicable regulations.


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## Mark K (Nov 28, 2017)

"accepted engineering practices" is vague.

I would say that this beam needs to be designed by a registered architect or engineer in accordance with the provisions in the IBC.


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## Pcinspector1 (Nov 28, 2017)

mark handler said:


> Accepted Engineering Practices consist of proven engineering methods, procedures, and practices that provide appropriate, cost-effective, and well-documented solutions to meet requirements and compliance with applicable regulations.



Mark, do you have a rubber stamp that sez all of that?  or the one that Mark K posted *"accepted engineering practices" *is vague.


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## conarb (Nov 28, 2017)

Mark K said:


> "accepted engineering practices" is vague.
> 
> I would say that this beam needs to be designed by a registered architect or engineer in accordance with the provisions in the IBC.


I've worked in an AHJ that not only requires an engineer's stamp but siesmic loads applied in 4 directions, then wind loads superimposed upon those siesmic loads, we don't have snow or I bet they would require snow loads apllied to those superimposed wind loads.  I've had them make me bring my engineer in with the engineering program he used and watched the plan checker SE make my engineer go thhrough the process.  At my next meeeting after he made changes they agreeed on she asked me: "Where did you find that guy?"


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## cda (Nov 28, 2017)

Pcinspector1 said:


> Mark, do you have a rubber stamp that sez all of that?  or the one that Mark K posted *"accepted engineering practices" *is vague.




Some people you have to spell out all the requirements


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## Mark K (Nov 28, 2017)

Conarb

Your plan checker who required both wind and seismic at the same time was wrong.  Asking the engineer to bring in the program is hard to justify.  Where did they find the plan checker?

The problem here is one where there is no clear solution in the IRC and thus you need to look to the IBC.  Also in California the licensing laws would require an engineer or architect to design the beam.


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## MT323 (Nov 28, 2017)

Pcinspector1 said:


> The WFCM (Wood Frame Construction Manual) has ridge beam capacity requirements for interior center bearing roof and ceiling, you'll need the snow load to use the table 2.16, engineering is advisable, you'll need fastener information and bearing requirements at the beams ends.


Once I know the capacity how do I determine the beam's size and spanning by engineering methods? There's also a table on ridge beam spans in the prescriptive part, which for some reason is not present in the irc. Should I better use that?


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## classicT (Nov 28, 2017)

Non-Prescriptive Construction => Follow IBC => Designed by an Engineer


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## conarb (Nov 28, 2017)

Mark K said:


> Conarb
> 
> Your plan checker who required both wind and seismic at the same time was wrong.  Asking the engineer to bring in the program is hard to justify.  Where did they find the plan checker?
> 
> The problem here is one where there is no clear solution in the IRC and thus you need to look to the IBC.  Also in California the licensing laws would require an engineer or architect to design the beam.


Mark:

The home was designed using a German engineering program, I asked her if she had it and she said yes, she is a SE.  She finally admitted that she didn't have that program but that she had used it in a prior jurisdiction, so she asked that my engineer provide nodal points so she could transfer it to her program, finally she admitted that she couldn't transfer the nodal points and didn't have that program and asked me to bring my engineer in with the program loaded on a laptop so they could go over design forces together.   I agreed and stood over them while he animated the program, he was bringing forces from two directions so she sent him back to redo it with forces from 4 directions, once he started animating the seismic forces she then demanded that he superimpose wind loads from all 4 directions, I stood over them and watched the whole procedure.  I must say that these computerised animated design programs are impressive to watch, as forces are applied you can watch the frame flex throughout the structure, in this case my customer was educated as a mechanical engineer and had no problem with the added requirements or the additional costs assoicated with complying with them, but not everybody can afford this kind of design, one column to beam change agreed upon ended up costing an additional $44,000, when I told the customer he merely asked if it would make his house stronger?  When I said yes he readily agreed to pay the additional amount.


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## Francis Vineyard (Nov 29, 2017)

The following definition from the 2015 Residential Code Essentials is the same found in the (2015) IBC commentary:
*accepted engineering practice *– Engineered analysis based on well-established principles of mechanics and conforming to accepted principles, tests, or standards of nationally recognized technical authorities.

IRC commentary explains one of the reason for accepted engineering practice  "it is difficult to accurately and fully present all of the support methods in one set of prescriptive provisions." 

R301.1.3 also provides for an engineered design in accordance with the IBC is permitted (not prohibited) and the AHJ or state law may determine the when a seal is required. Some states may allow manufacturers documentation of their specifications, or the plans signed by the individual (not company) responsible for the design, including the individual's occupation and address. 

http://www.southernpine.com/app/uploads/SS_15-20L.pdf


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## cda (Nov 29, 2017)

MT323 said:


> Once I know the capacity how do I determine the beam's size and spanning by engineering methods? There's also a table on ridge beam spans in the prescriptive part, which for some reason is not present in the irc. Should I better use that?





So is this house in the Republic of Latvia??


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## MT323 (Nov 30, 2017)

cda said:


> So is this house in the Republic of Latvia??


Yes it is.
No inspectors will check it, i just need to make sure it is safe.


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## conarb (Nov 30, 2017)

cda said:


> So is this house in the Republic of Latvia??



Be sure to comply with ADA, you may have imbeciles moving in there.


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## cda (Nov 30, 2017)

MT323 said:


> Yes it is.
> No inspectors will check it, i just need to make sure it is safe.




Ok send the plane ticket and hotel room

Will be there


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## JBI (Dec 4, 2017)

Theoretically, you could use the beam tables in Chapter 5 of the IRC and base it on the applicable loads the roof is likely to have applied to it... 
Kudos for wanting to do the right thing MT323.


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