my house is wood, two story, sloped roof with a wood, one story , almost flat roof addition.
because of annoying leaks on the flat roof i want to build a sloped roof on top of the flat roof.
it will be exempt from local codes because the house is grandfathered. it was built before there was a town.
my question is, is there an easy way to figure out if i should use 2x4, 2x6, etc. based on the length of the lumber i use ? the flat roof is 29' long by 9' wide. i am thinking of useing a ledger to attach it to the side of the house. like a deck. it will be about 3' off the flat roof on the house side and lay on top of the flat roof on the other side. leanto style. i guess the new roof will be about 12' wide.

/\ house
l l
l l- flat roof
l l l


this is what i have.


/\
l l
l l \ sloped roof
l l l

this is what i want to build. roughly.

 

Get some help figuring the spans, I did a similar job and the building inspecter helped me. Your lumber yard will also help. I would check with the city or county to assure that no permit is required, I have never heard of that. I got rid of my flat roof on my old house, best thing I ever did.

 

thanks for the advice on going to a lumber yard. i knew i could do that, i was just hoping there might be a formula i could work out on my own.

as for no permit required, my house is a " non-conforming house " built before the town had zoneing laws. which means i am grandfathered. they cant force me to bring the house up to code, which would be impossible anyway, and i dont have to follow current codes. as long as i dont put on an addition. since i am only repairing a leak, i am exempt.

in case your wondering, the town does not like it. i know they are praying for a fire or earthquake to seriously damage the house so they can condem it and have jusidiction over the new house.