# Truss or Conventional Frame??



## mbaybut (Dec 20, 2012)

Hi,
I have an upcoming project where I want to extend my roof to cover a porch. I'm just trying to educate myself here so I can follow what's being proposed by contractors. I did have one contractor suggest a flat roof but I'm inclined for a low slope. 12:1 or 12:2 ? Would this job suit truss or a conventional framing job? Any other advice would be truly appreciated.
Thanks,
Mike


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## AnyMonkey (Nov 26, 2012)

the biggest concern i have with your drawing is that you do not have a support post at the corner of your new almost flat roof. Cantilevered roofs should have a ratio of 2 to 1 which means that for every 1 foot of roof that hangs out it should be supported by 2 feet of internal framing. I am assuming that your rafter size ie 2x6, 2x8, 2x10 etc would also be determined by the amount of overhang you have but i do not know what the ratio of this could be. It is also likely that the current roof trusses were not engineered to support a cantilever design. This is not a project I would jump into if i were you without the right carpenters and advice


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## mbaybut (Dec 20, 2012)

Thanks,
Sorry about that. It was never intended to be a cantilever roof. I just posted the pic before I had the columns in. Any other suggestions now I've corrected my mistake?
Thanks,
Mike


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## AnyMonkey (Nov 26, 2012)

myself i would consider making a flat roof and then puting a 2% sloped ISO insulation on it and putting a torch on roof in this section as per my drawing


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## mbaybut (Dec 20, 2012)

Thank you.
Is that an easier, better way to achieve that look. What pitch does a 2% come out at? How does the cost compare with conventional framing?
Thanks again for your time and help,
Mike


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## AnyMonkey (Nov 26, 2012)

well the problem that i see doing it with carpentry is that you would have to do it truss style rather than straight rafter because with rafter style the existing shingle fascia would be visible from the bottom... cost wise it is probably not much different but with the insulation all you need to do is remove the shingles to accomodate the torch on but if you do it with carpentry you will most likely need to remove the shingles and plywood in that area to tie things in nicely. just my opinion of course. myself i would have probably just considered a metal awning instead.


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## AnyMonkey (Nov 26, 2012)

2% is not much as far as slope goes but it is the amount that plumbers and road builders use to get water to move which is ultimately the goal you are trying to acheive. 1 in 12 is approximately 10% slope to give you an idea.


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## shazapple (Dec 3, 2010)

It really depends on your span. A little chat with a truss company should point you in the right direction. 

Personally I'd go with a "flat" roof. Shingles on anything less than a 3:12 is asking for trouble.


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## mbaybut (Dec 20, 2012)

Thanks. That's the way it's looking.


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## ckakarate1 (Mar 19, 2013)

Hi,

I am trying to find out if there is a rule of thumb for using roof trusses instead of convention framing. Is there a break even point? 

I will be managing a job that is a 15X30 one story ell addition coming off the back of a house, so there will be valleys, etc. There is a 13X30 one story ell there already, so we will be stripping off the existing roof and adding to the width. The old exterior walls will be kept, so there may be a bearing wall in place already. (I've never been to the site, which I deem a mistake on my employer's part, and no one else has the gumption to go into the crawl space under the existing ell to see to what extent the existing has rot, that's why I say "may be".)

The in-house designer is calling for trusses, and I am wondering if this is really the best way to go. Considering every truss package we order comes through will some type of foul-up, I can't see there is a time benefit.

So there's the question. When does conventionally framing the roof make sense, and when do trusses make sense? It's 23 pairs of rafters plus the tie in.


Thanks.


__________________________________________



San Jose Karate
Sunnyvale Karate


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## roofermann (Jul 7, 2012)

New construction, trusses win. Remodels where things might not be square/level/plumb? Stick build it. Use engineered lumber where possible. Enjoy!


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