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As an M.Arch student, a friend of a friend hoped I could assist in drawing up plans for a new roof pitch on their home in Los Angeles. They will be contacting a Contractor to do the work. What do I need to provide, what can I legally provide, to assist them?
not sure about the code in LA, but generally if the roof can be conventionally framed, you are not on the hook for anything. If the roof is designed by structural analysis then an Arch or Eng needs to stamp it. I'm assuming your friend is looking for you to produce drawings for permit. This can go a million different ways and your liability can be extremely limited. Don't put your name on it. Sell drafting services only. Most importantly be extremely clear about the service you are providing for your friend up front. Good exercise in code research and contracts. Again I do not practice in California and am making assumptions about the laws in your State. You need to research them.
That being said, I have no idea why anyone would propose the change you have shown. Doesn't look like anything other than a waste of money. How does this change in roof slope improve the home? Why are they doing it?
maybe they are changing the flat ceiling to the new vaulted ceiling / roof
that would really open it up
can they gable the flat roof 90 degrees to the existing gable so there are two valleys where the new gable meets the old gable gable matchy gable?
If they were going to vault the ceiling in the manner that is being depicted, it would cost twice as much as simply ripping off the entire roof and starting over. It also would required structural analysis. If that is the case, they want a vaulted ceiling, better to start from scratch and not restrict yourself to the existing roof profile.
Based on the climate of Los Angeles, compared to other cities in a similar climate like Pheonix, San Diego, Tuscon and Las Cruces, I'm going to guesstimate that a 50-year rainfall event is probably around 6-8" over 24 hours. So, it's not completely unlikely or impossible, for LA to have a 1-2" an hour thunderstorm.
And the original roof would likely fail and leak in the event of a rare, but possible, heavy thunderstorm. The new proposed roof would give the occupants peace of mind in that regard.
Also, the new roof slope would allow for more insulation to be added which can have a significant impact on cooling costs if the flat roof gets a fair amount of sun.
why are they doing this?
clearly we need to know
Send the sketch and back away - this is going to be a very complicated/expensive endeavor and it's best not to be around to suffer the blowback if you don't also have the experience to clean up the mess.
Keep in mind that sometimes the best projects are the ones that you aren't involved in!
In California if this is type V construction you do not need any licence or calculations, you can simply download guidelines for type V submission and follow them.
to obtain permit without involvement of structural engineer you will have to produce structural drawings as well as architectural, attach type V standard sheet ( which provides standard calculations, you can obtain it in Building and safety), but all this makes you responsible. City will review and will make you change plans several times before releasing permit, that is how they make their salaries. it is a lot of hassle. if you are doing this as a favor it does not worse it.