cantilevered front enterance landing?

[ovidgsd]

the floor of my single floor cabin will be about 3 feet above grade.  Instead of using a ledger to attach an exterior exposed landing for the front enterance, I was thinking of doing a cantilevered landing - 4 feet wide and 3 feet out from the building. This way I don't need posts on the ground at the outside of the landing where the stairs begin.  The landing will be protected by an overhang above, and walls on the sides, but the opening will be exposed - no door - so some snow and rain will get in - not likely much

Considering that the landing will essentially be the same level as my floor, if it is weather proofed on 3 sides and protected by flashing at the joint with the building, will that be enough waterproofing?

My stairs hang off the end of the cantilever - my floors are 2x10's.  I'm thinking of using 10 foot long 2x10's to create the cantilever - 7 feet under the floor inside the building and 3 feet cantilevered outside?  Will this be sufficient support for the overhang, 2x4 walls for the overhang and the stars hanging off the end of the cantilevered landing?   (the building walls are 2x6)

[MountainDon]

Is this projected   cantilever coming off a long side as a continuation of the main floor joists? Or off an end where it would be constructed as a sub structure under the main joists?

I'd want to be careful about making a pathway for liquid moisture to be drawn back underneath with the possibility of damage to the main joists, subflooring or beams.

[ovidgsd]

MountainDon,

Yes, the moisture question is my primary concern.  I was hoping that if it is protected on 3 sides and from above, and then substantial flashing and silicone caulking at the transition, would be enough...?

This "proposed" cantilever would be a continuation of the main floor joists.  The main floor joists are to run perpendicular to the roof ridge and are 16' long 2x10's at 16" o/c.  The main floor joists will sit on top of 3 thick built up 2x12 girders.

[MountainDon]

All I can say is I considered the same thing as you during the design stages of our cabin. After much back and forth and input from PEG I decided it was a bad idea, or at least an idea that could have bad results at some future point. Perhaps overly conservative. 

[John Raabe]

Some of the problems you have in an exterior cantilever:

• 
  Your decking usually pushes the floor level on the outside above the floor level on the inside. This invites water problems. An exterior deck should be about an inch lower than the interior floor to allow for the threshold, weather stripping and drainage to work properly.
  
• The joists and all decking material should be PT or they won't last. If the deck joists are continuous with the interior floor joists, and they start to rot, you will have a nasty problem and probably have to replace some of the interior floor.

[ovidgsd]

Well, looks like the thing to do is make this "exterior" cantilevered landing and interior one........this way I have my landing and I have it weatherproofed to thwart all the water infultration issues. 

the building is a 16x16 square - gable end roof 2x6 walls.

The main building walls are 12 feet high.  The Cantilevered landing will be on the roof end pitch side, not the gable end side.  I'll run 4, 2x10's with the main joists that are 12 feet long sticking out 42" and 16" o/c.  Then I'll frame off the little cantilevered landing with uninsulated 2x4 walls 8 feet high and a single pitch roof (matching red metal to the main roof  ).  Slap on a storm door and now my cantilever is water tight, and the "mud room" entrance I need   Siding to match the building.

Are these 4, 2x10's enough to support the 2x4 walls and the stairs ? or do I need to double up? (the stairs will rise 3' from grade, but will be long, not steep (I have an old dog with weak hips!))  I can frame the single pitch roof first to be all load bearing on the Main 12 foot wall.........