Building a sleeping porch fully under a roof?

[cre8tiff]

I am making a sleeping porch off an upstairs bedroom utilizing some unused space under our very high pitched roof. The end will be open to the elements, so I expect I need to pitch the floor, but I want the porch floor boards to run perpendicular to the building, NOT what rafters are dictating. Also, the sleeping porch is over a veranda, so while I don't want water coming down there, I don't have drywall to protect, either. So here is what I think my options are:

A) DARN your wants and put those things across the existing rafters, and like it!

B) Build a cross framework to put the boards on, Bob Vila!

C) Put down plywood subfloor then run the boards whichever way you want.


Now I prefer C) but am concerned the subfloor might cause problems with the opening to the elements. Would I need something like marine plywood $$$$? How about tar paper sandwiched between the subfloor and pine flooring (well painted, of course)?...what do you suggest?

BTW the rafters are 16" on center 2 X 10's.

Thanks Loads!

Darin

[homebild]

What you can and cannot do dictated by your local building codes and overall building's loads.

None of which you supply.

You also do not tell us how this sleeping porch is being supported.

Will it be cantilevered into the existing floor joists?
Supported free standing?
Bolted to the house using a ledger board and support columns?
Other?

What are you spans?
What size lumber, species, and spacing on center?

How high from the ground?

Answer a few of these unknowns and we may be able to help.

[cre8tiff]

The porch is within our posted zoning requirements either way I do the flooring. They are more concerned with rails and stairs. As long as I have the 2x10s as supporting members, they have indicated it would be fine.

You asked for a few specifics, here they are:

The porch is already built into the house framing. It was an unused attics space in the second floor.

The floor is 12' X 18', with the 12' being the span of the rafters.

It is tied into the house framing (load bearing wall) on one side.

The other side is supported by 4x4 pillars at 5 foot intervals. The way the porch is set up, three of these pillars are supporting the are in question, one in the middle and two five feet away to either side.

The lintel that rests on these posts is doubled up 2x10. The rafters running from house out to this lintel are made of (I presume) pine and are 2 x 10's, 16" on center. Some are sistered, but for what purpose I don't know as they are not cracked or warped, and I would not be against sistering the rest if you think it would help.

The porch will be the same height off the ground as our second floor ~8-10 feet.

Does that help?

Best,
Darin

[cre8tiff]

Man, was it something I said? :wall: