New deck w/ screened porch & roof


Corporate Member
I have had an engineeer spec the joists, girders, rafters, etc. and now have contractors saying "you can't do that by code"..
That's probably more of the contractors know how to do it one way, the way they've always done it, and don't want to follow what the engineer says as that's usually more complex. I would show what the engineeer says how to do it to the county and get them to pre-approve and sign off on it, and then find a contractor willing to do it the way the engineer says. It takes a 5 hour class to become a contractor, but many years of study to be an engineer. I'd rather an engineer sign off on how to do it than a contractor.

As for the septic, if it's that old don't touch it. Don't let anyone drive on it or dump supplies on it when you're building. Repairing old systems can get very expensive. Had a property being sold that the soil engineer solution to failed septic was going to cost about $20,000 to get working, and required a lot of hauling in stone and dirt. House next door was condemned by county because nobody could figure a way to repair its septic.


Corporate Member
A Deck like this is simple, design for 50 lb per sq ft load. That is the same as most floors. The real concern are couple other things the support and the water proofing to the home.

The support foundation should have enough depth into the ground. Me? I would make them out of 12" round 18-24 " into the grade. Make sure the post to beam have correct metal brackets to support. The framing needs to be independent enough so it is not dependent on the house, In a hurricane or earthquake the asymmetrical reaction force will cause them to move differently, if the deck is dependent on the building as a mean of support, it fails. Saw this alot in the Loma Preita earthquake. Look up floor joist spans for 12' @ 24"centers, my guess it would be 2x10. One other thing, if you use a composite decking, I would go 16", this prevents any kind of sagging due to extreme heat and weather.
The other thing is the connection to the home, what has been the standard the last 10 years is using Ice and water shield (bithuthene) and a z- type flashing. Then, they usually go with a 2-3"wall side up with a 1/4-1/2"90 bend kerfe'd into the building set in a Low modulus (Sika 15lm or equal) caulking.
See the attached photo. I have done this detail at least 2000 times. Seems like alot, but this been the standard in the west coast for a long time. Mostly done on Apts or Condos, .


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