what is the hourly wage for a good construction assistant these days in southern California.? Used to be about $17.00 per hour for fer a guy what can run saws ,measure and assist in all phases and that was back in the 80's. That is what you call a good all around helper worth keeping. So ,say on a such a deal he ,the helper excepts $600.00 ,there, there abouts. 2nd story deck is a two people operation every step of the way.I never knew 8 hour days in all my years in construction. More like 10 or 12 in the field than paper work at home or in an office.
So the question is, does your builder friend/neighbor have nothing better to do ,semi retired ,just happens to be around a lot, I dono. !
And since your are bumping it out, I assume you are going to go with permits.And so what is your builders plans on all that, will it be free standing ?
And it seems like you are telling your builder friend how much time you will allot in time is money. Remember your builder friend is no used car salesman ! And you cannot control the clock. 6 to 10 days to do it tells me he doesn't see it as a cake walk if you know what I mean.
If I were you I would present that offer to the tune of ,would you except $3,000.00 and I'll help you.
It seems to me you might be a bit too far on the low end.Earth quakes and all the SHED,you are looking tword your builder friend because you know he is real builder right? So you want it done right,right? You want to go ahead with it knowing somebody really knows what he is doing,right?
Pitch your offer,see what he comes back to you with. Or,correction, that's your carpenter friend.
That or keep getting estimates.
Good luck- with your project-your deck will no doubt be very cool.