If you were Registered and logged in, you could reply and use other advanced thread options
|
Posted by Wayne Whitney on July 10, 2007, 2:10 pm
Hello,
I've noticed that in my 1908 wood frame house, the roof rafters do not
bear directly on the exterior wall top plates. Instead, a 1x4 is run
along the top of the 2x6 ceiling joists, and the roof rafters bear on
this, usually over a ceiling joist. Is this a currently acceptable
framing practice?
I'm adding a (very) small addition with a separate roof, and I'm
wondering if I should use this detail. Repeating it would likely
facilitate matching the overhang, soffit and freize board details of
the original house. FWIW, the basic wind speed at my urban site is 85
mph, the design earthquake load is 0.17 W, and all roofs are 8:12
slope and hipped.
Thanks, Wayne
|
|
Posted by RicodJour on July 10, 2007, 3:16 pm
> Hello,
>
> I've noticed that in my 1908 wood frame house, the roof rafters do not
> bear directly on the exterior wall top plates. Instead, a 1x4 is run
> along the top of the 2x6 ceiling joists, and the roof rafters bear on
> this, usually over a ceiling joist. Is this a currently acceptable
> framing practice?
Very little of a 1908 house would conform to the current code.
They're still standing 100 years later, but they don't fit the code.
> I'm adding a (very) small addition with a separate roof, and I'm
> wondering if I should use this detail. Repeating it would likely
> facilitate matching the overhang, soffit and freize board details of
> the original house. FWIW, the basic wind speed at my urban site is 85
> mph, the design earthquake load is 0.17 W, and all roofs are 8:12
> slope and hipped.
There's not reason to use such an odd detail. Any engineer or
building inspector would have you doing so much extra work to approve
that detail that it would cost you far more than any perceived
benefit.
Place the rafter/truss on the top plates, raise the wall height if
necessary to match roof and soffit lines, build the ceiling and
soffits down to match existing.
R
|
|
Posted by Wayne Whitney on July 10, 2007, 3:19 pm
> Very little of a 1908 house would conform to the current code.
> They're still standing 100 years later, but they don't fit the code.
Right, that's the reason I'm asking. :-)
> Place the rafter/truss on the top plates, raise the wall height if
> necessary to match roof and soffit lines, build the ceiling and
> soffits down to match existing.
Thanks for the advice.
Cheers, Wayne
|
|
Posted by Alan on July 11, 2007, 2:01 am
The recommendations about the code issue is correct, but you can bring
it to code with Strongtie metal connectors easily enough. If the
ceiling joists are blocked on the ends, then really it will probably
satisfy the inspector for the seismic requirement, though not for the
wind. I would beef up the standards for the wind to 125mph
regardless. 85mph is just too low anywhere, really. I live in
California where wind requirments are low, and just two winters ago we
had storm winds as high as 65mph. I would feel uncomfortable with
just 85mph here. You certainly want to match the architectural
details of the original house to keep your property value high,
whichever way your plan the framing.
>
> > Very little of a 1908 house would conform to the current code.
> > They're still standing 100 years later, but they don't fit the code.
>
> Right, that's the reason I'm asking. :-)
>
> > Place the rafter/truss on the top plates, raise the wall height if
> > necessary to match roof and soffit lines, build the ceiling and
> > soffits down to match existing.
>
> Thanks for the advice.
>
> Cheers, Wayne
|
|
Posted by Chuck on July 11, 2007, 3:56 am
>> Hello,
>>
>> I've noticed that in my 1908 wood frame house, the roof rafters do not
>> bear directly on the exterior wall top plates. Instead, a 1x4 is run
>> along the top of the 2x6 ceiling joists, and the roof rafters bear on
>> this, usually over a ceiling joist. Is this a currently acceptable
>> framing practice?
>
> Very little of a 1908 house would conform to the current code.
> They're still standing 100 years later, but they don't fit the code.
>
>> I'm adding a (very) small addition with a separate roof, and I'm
>> wondering if I should use this detail. Repeating it would likely
>> facilitate matching the overhang, soffit and freize board details of
>> the original house. FWIW, the basic wind speed at my urban site is 85
>> mph, the design earthquake load is 0.17 W, and all roofs are 8:12
>> slope and hipped.
>
> There's not reason to use such an odd detail. Any engineer or
> building inspector would have you doing so much extra work to approve
> that detail that it would cost you far more than any perceived
> benefit.
>
> Place the rafter/truss on the top plates, raise the wall height if
> necessary to match roof and soffit lines, build the ceiling and
> soffits down to match existing.
>
> R
R
Is correct, raise the wall plates to the height of the ceiling. I would
recommend that you use manufactured roof trusses in lieu of conventional
framing. This way you won't have too many connections to be concerned with.
It will be cheaper and the trusses would be installed in one day. Make sure
you have a good, preferably, plywood sheathing for the roof so you can
develop a diaphragm to resist lateral forces i.e. wind and earthquake.
Don't worry about the 85 mph many code areas are using this value but you
need to follow the ASCE7-02 loading criteria which increases loads based on
location. The wind forces get greater the higher the structure, at corners
of buildings edges of roofs etc. This is required by the IBC 2003 building
code. You need to have a detail so that the sheathing can transfer the
lateral wind/eq force to the sheathing on the walls ( shear walls ). If
you are getting a local authority permit for this construction you will have
an inspector. Hopefully the inspector might not recognize a lack of
connection of the existing roof diaphragm to the exterior walls. But he/she
might, then, you will have to fix all edges of your roof. Luckily there are
exceptions to this. How is the connection between the roof sheathing to the
exterior walls in the existing construction? Blocking would do it which
would be at the ends of ceiling joists nailed to the joist plates and to the
roof sheathing. If, you don't have blocking at the ends of the ceiling
joists you might be able to fix your whole roof system by adding blocking
all around nailed to the existing wall plates and the sheathing ( if you
have any ) to take the wind/eq forces to the walls. Do you have wall
sheathing on the existing walls? Where are you located?
If you are going to need foundations for your project I guarantee you that
the permit authority will require a structural engineer to design foundation
and do the seismic and wind load design. If this does happen you should have
the engineer check your roofing sections and details so the permit process
will be smooth and easy. At this point you should check your costs and see
if it all is in your means.
Sorry, that this has taken so long but these are things that engineers and
architects go through quite often on many projects.
Hope this helps.
CID...
|
| Similar Threads | Posted | | Question about roofing | July 23, 2007, 11:23 pm |
| Question: How To Stretch Lifespan of Tin Roofing | November 25, 2006, 9:08 pm |
| Garage Framing Question | August 21, 2008, 3:54 pm |
| Question on Framing Exterior Corner | May 28, 2007, 2:52 pm |
| Slab on grade framing question... | July 26, 2007, 10:54 pm |
| Roofing | February 17, 2007, 5:25 pm |
| Re: roofing types | July 15, 2006, 4:20 pm |
| stucco before roofing? | September 16, 2006, 12:47 am |
| going rate for roofing? | September 26, 2006, 2:36 pm |
| spray on roofing | April 8, 2007, 11:24 am |
|
|
Yahoo! 
Google 
Windows Live 
del.icio.us 
digg 
Netscape 
XML Sitemap