What is the code-required lap joint overlap needed on a 2/12 roof?
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I HAVE A 2/12 (permitted) LEAN-TO STYLE ROOF IN TAMPA, FL. JOISTS ARE 16 O.C. THEN PLYWOOD AND CLIPS, THEN 30 WEIGHT FELT PAPER WITH THE STANDARD 3 INCH LAP JOINT. FELT IS NAILED OFF 6 INCCHES O.C. ON THE LAPS, AND 12 INCHES O.C. IN THE FIELD. I PLAN ON INSTALLING 5V CRIMP 26 GAUGE METAL IN ONE PIECE FROM RIDGE PEAK TO TAIL ON BOTH SIDES OF THE ROOF. THE INSPECTOR SAID THAT HE THINKS WHAT I HAVE ON THE PRINTS WILL PROBABLY BE ALRIGHT, BUT HE NEEDS IT IN WRITING BEFORE HE CAN PASS ME. CAN YOU PLEASE SEND THE THE FL # OR SPECS THAT I NEED? THANK YOU, JON BRIGGS (407) 301-4527
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I don't see any way this can meet code. 5-V needs more than a 2/12 pitch, so it's only listed to keep the sun off a waterproof substrate in this application which your 30 lb paper fails to provide. You'll need to upgrade that to a hot mop or possibly a roll roofing double lapped with full asphalt adhesion. At this point the tin is just a shading strategy and should be furred up on strapping and you would want to address the holes where the strapping is attached.
Good luck with it. I think roll roofing without the tin is likely your best bet.
White roll roofing in your climate.