Open air under cantilever

[brnhornt]

Hi all,

I'm having a patio replaced at my house and came across one small issue.  There is a section of the kitchen that is cantilevered out from the foundation.  It's just a section of french doors...so say 10 feet wide, and 3 feet away from the house.  The plywood underneath (above the ground) has fallen away and the insulation has fallen.  No brainer to get under there, clean it all out, maybe spray some clorox cleanup just to kill any type of mold that might have found it's way, add more insulation and then screw on a new piece of 1/4" ply.  My question is about vapor barrier.  I'm thinking I will paint the bottom side of the ply with any latex I happen to have laying around the house...but think it's worth putting some poly on the ground itself?  

Second part....the large wide portion of the front of this space will be closed in with a set of stairs...leaving just 3 feet of the left and right.  Previous owner (or builder) had that closed off with some 1x12s.  Would it make sense to cut in and install a louvered vent on the left and right so that air can move thru that space?

Thanks for any input!
Kevin

[EricU]

So it's less than a foot above the ground?

I don't know if a poly barrier on the ground is going to do anything, but around here, we would have varmints under there.  I think I would lay down a couple inches of gravel to keep that from happening.

[brnhornt]

So it's less than a foot above the ground?

I don't know if a poly barrier on the ground is going to do anything, but around here, we would have varmints under there.  I think I would lay down a couple inches of gravel to keep that from happening.

Yeah...I didn't take a measurement last night but it's 1 to 2 feet.  The steps on the front face and the boards on the left and right side would seal the space off from animals getting in...

[Roly]

So it's less than a foot above the ground?

I don't know if a poly barrier on the ground is going to do anything, but around here, we would have varmints under there.  I think I would lay down a couple inches of gravel to keep that from happening.

Instead of plywood I would use a pvc panel.  That would eliminate the painting and rot.   Wall type latex paint will not prevent anything,  If anything a acrylic house paint or other enamel would be better.  Around my house the skunks would setup  housekeeping under there.   Agree with blocking it off but allow ventilation.  Roly

[EricU]

our varmints are pretty adept at digging, thus the gravel.

[brnhornt]

our varmints are pretty adept at digging, thus the gravel.

I see your point...the left and right boards will end on plane with the concrete slab that will be poured.  Meaning the new pavers will butt up against...hence preventing any kind of digging.

[crokett™]

pictures would help

[brnhornt]

pictures would help

Good point...I don't have anything specific to the area exactly...but this crop of an overall shot shows it:
[attachment=11255]

The red circle is the area beneath the french doors in question.  The discoloration of the bottom two courses of siding under the doors are from the previous steps...so the new steps would cover entire door-wall to the same level.  The PT wood would need to be up/under the left/right sides.  Sealing the whole thing up.

[brnhornt]

...also to add...the diagonal line visible under the space now is the fallen 1/4" ply.  That would be removed, and new fiberglass insulation put up with a final piece of new 1/4" put back.  If I seal it all up as well as I am imagining...that becomes a stagnant air that would love to get moist and cause mold/rot.

[crokett™]

Why doesn't the plywood cover the area under the steps/doors? Unless I'm mistaken, I'm thinking the plywood is attached to the edges of the joists underneath the overhang to cover the insulation. I would use PVC sheets or something that doesn't rot. As long as the stairs and the 1x12s or whatever seal that area up, yes you need to add some sort of vents to allow airflow through it. I don't think you need vapor barrier on the ground.