[qslim]

I've noticed over the past week down here on the panhandle of FL that the concrete floor in my sunroom is steadily accumulating moisture. We had some decent rain about a week ago, and since then it's been humid as with temps around 70. There is a small circle right in the center of the room with small beads of water, and the same thing around edge of the floor at the bottom of the exterior walls. The room is a concrete slab, painted by the previous owner and set about 10" below the bottom floor of the house. The walls of the sunroom are brick, about 3' high with windows going the rest of the way up to the ceiling. There are no visible cracks in the floor.


The house was built in '80, and I just installed gutters last month. I've noticed the water on the floor a couple of times, but it hasn't been this bad before (I just bought it in Sept). I don't know a lot about this sort of stuff, whether this could be fixed by simply sealing the concrete or if it is a symptom of something else requiring repair. Thanks for reading here's a pic if it helps:

 

[joecaption]

Post a picture of the outside.

 

[qslim]

Thanks for the quick reply. Here's a shot of the long wall, you can see the trench the lack of gutters carved out over the years about two feet out from the wall:

And here's a shot of the other far wall making the corner that has the most moisture right now:

And if it matters I'm on the Panhandle of Fl, about 60 feet above sea level and my yard is very sandy and soft.

 

[joecaption]

Is there any heating run under that slab?
Make a guess as to how much higher that slab floor is to the outside grade.

 

[qslim]

No, no heating. The whole house sits on a slab and the hvac system is in the attic.

There is about a 3" drop at the threshold where the slab stops and the exterior walkway starts.

 

[jomama45]

It clearly looks to be "sweating", or condensating. Usually happens when warm, humid air hits a much colder surface. Not much you can do to "retrofit" a vapor barrier under the slab, and I'd be wary of anything than claimed to serve as a VB from the top. You may just have to get a little more air movement in the room........

 

[joecaption]

Or a dehumifier.
Around here were required to is a vaper barrier and foam under a slab to prevent what you see happening.

 

[Gary in WA]

http://www.buildingscience.com/documents/insights/bsi-037-mold-in-alligator-alley

Fig.2; http://www.buildingscience.com/documents/insights/bsi-059-slab-happy

Fig. 6-9; http://www.buildingscience.com/docu...nvestigating-and-diagnosing-moisture-problems

Gary
PS. your fence and shed appear to slope toward the house... run the splash-blocks farther away.Check for termites/add f.b. or a french drain perimeter.

 

[stadry]

there are epoxies that will resist up to 30# rising moisture/wtr iirc,,, they can be colored or quartz/vinyl chipped,,, might be hydraulics as ' decent rain ' is a clue,,, 1 can have retrofit vapor barrier installed by pumping expanding foam grout thru the slab from inside,,,we don't often do that but sometimes its the only way to resolve issues

 

[jomama45]

Or a dehumifier.
Around here were required to is a vaper barrier and foam under a slab to prevent what you see happening.

That's great, but this is in Florida, and it's 33 years old. First, VB's weren't common under floors back then, and second, you'll be hard pressed to find foam insulation under a floor in Florida, even in new construction today........

 

[qslim]

Thank you for the input. Joe, I think you're on the right track with the humidity. Just a few months ago I replaced all the flooring throughout the house, and there wasn't any evidence of water having come through the interior house slabs at all.. And just last night it rained like hell and brought in a lot of cool dry air, and this morning the Florida room is bone dry (even during the heavy rain). Maybe I was associating the wet floor with the rain before and not thinking about the humidity.

GBR, thank you for those links, there is some good reading in there.