"The floor was raised to the house level with a wood frame and plywood on the slab. The floor was removed this last weekend (horrific, moldy, disgusting mess, "

before you move forward you need to understand the
reason this happened.

when you build a house on a slab, plastic vapor
barrier is installed on ground, then the concrete is
poured. without this vapor barrier, moisture migrates
from the ground into the slab. concrete absorbs
moisture.
for garages porches & patios this extra step
of adding a vapor barrier to the ground just isn't done.

your problem isn't uncommon for garages, patios
porches turned into living space. unless contractor
has put vapor barrier under these non living spaces..
they will absorb moisture. not a problem if you aren't
turning the space into an enclosed living space.

so what to do?
vapor barrier on slab (felt would also work) sleepers
then sub flooring. otherwise the flooring will rot again.

what is your location?

best of luck.

Thanks for the info! I am in SE Louisiana so water is a huge issue.

Would it be acceptable to just use a masonry waterproofing like drylock (or any others??) on the floor? I really don't want to put a floor over the slab, I was just hoping to stain/paint the concrete.

use only water based products.
this will allow moisture diffusion into the
garage area, if you use products that
don't allow this diffussion then the products
will fail as moisture from the slab/ground
is trapped.

I'm sure you've seen signs of trapped
moisture behind paints, the moisture collects
and the paint bubbles.

you mention a dehumidifier, once the
floor is stained/painted the dehumidifier
would stay in this room to remove moisture.
as you do the renovations see if you can
locate the dehumidifier where it can be
plumbed in to drain. maybe through wall
to outside.

is this area insulated in walls & ceilings?
if not it will be difficult to heat & cool.
any pics to share?

best of luck

Poly on top of the concrete floor will trap moisture between the floor and the plastic, feeding mould growth. It just won't be as severe as with all that wood food. Instead, treat the garage floor as if it were a basement floor, allowing the moisture to move into the living space where it will be dissipated. XPS and plywood or Delta FM or equivalent will work well.

Maintaining the garage door(s) while finishing off the space is a ruse I've seen used to meet zoning rules requiring a garage. The first time I came across this reuse, the only entry from the main house was from the finished basement. I wasn't told about it and when I walked up into the former double garage converted to a family room with a wall of glass to the back garden I was completely disoriented, as if I had come upon a hidden world.

This post was edited by worthy on Fri, Nov 29, 13 at 18:54

Thank you both for the information - It is extremely helpful!

I am not sure if the outer wall is insulated. I would guess no, but we have not looked yet. Behind the wood paneling there is sheetrock. The outside of the house is brick.

The ceiling is somewhat insulated; we will be adding some insulation to the attic soon, though.

I am more concerned with cooling the room in the summer as opposed to heating it in the winter (we are from the North East - we can handle a little cold!! :-D). Moving a portable heater won't be an issue; just getting the cold air in will be. We were looking into adding some duct work for that area. The A/C unit should be able to handle it - the house is open to it now anyway, we don't run the A/C too hard, and when we came to look at the house several times over the summer, it was always about 60 degF inside! We keep it about 78-80 degF.

Worthy - I think this was probably a permitting and/or laziness issue as opposed to zoning! I have seen several other converted garages in the neighborhood. Since the door is in the front of the house, I don't want to put windows or a door in (looks silly to me), and like I said, I'd like to be able to eventually sell it with the option of turning it back into a functional garage :-). I would love to have the wall of glass though!

In this picture, you can still see that there is a little moist concrete spot - that used to be literally half the floor about a week ago.

Here is the inside of the door - there is some insulation between the soundboard and the door. This is right inside the front door, off the living room. The floor the previous owners had installed was level with the slab for the living space. In the whole house, there is/was linoleum glued directly to the slab - we have been working to pull all of that up and will eventually install a (probably floating) wood or bamboo floor.

knowing sq ft of house (including garage as you
plan to condition it) and size of hvac system
will give us a rough idea of the existing
system being able to handle added garage/living
space.

type of ducts & pic of plenum also helps.
is all of house including garage under
the same roof? or is garage under lower
roof?
you'll have to have access from one
attic to another to add ducts.
and depending on where the supply
plenum is & distance to garage you'll
probably have to upsize the duct to
move the air a long distance.

ok...the garage pics...
the paneling wall...is there a gap between
the bottom of the paneling & the slab?
moldings at wall @ ceiling?
that there is sheetrock behind it is
a good thing.

in second picture to the right
is that the inside of the garage door?

the key to cooling is to make the space
to be cooled air tight. you won't make it
100%, don't worry. but stopping summer
heat gain & air infiltration will go a long
way to reducing the amount of a/c
the space will require.

are you diy-ers?

and totally off topic but how did you
get from north to La.? oilfield?
where (generally) in se La are you?

as always I have more questions, but need
to get back in the yard to haul the stuff I've
cut down to the burn pile.
the few nights of frost have provided fuel
for the bonfire I've planned tomorrow night.
just need to get it from here to there!

We moved here for my job - chemicals :-). We're just west of New Orleans and the "suburban" towns. I love it, it's very quiet and small-townie, somewhere between suburban and rural. We're close to the river, within walking distance to the levees. It's wonderful!

The whole house is under one roof. I will have to get some information on the A/C and the attic - until recently it has been wayyy too hot to do much up there! Our winter project is to go up there and remove whatever the previous homeowners have left behind (of course!!!).

The sq. ft. of the house is just under 1700 including the garage. There is a small gap between the sheetrock/paneling and the slab - that is throughout the house under the baseboards so I assume that has to do with needing space between the wall and the concrete for moisture? The second picture is the inside of the garage door.

As far as DIY, I'd say that we can do the basic to intermediate (with some practice) projects. When I was younger, my dad was really big into DIY and remodeling houses, so I have done a lot of work on water pipes, electric, flooring, etc. I have enough knowledge to know what I am comfortable doing and what I will need help with from someone more experienced. There are a lot of people I know around here willing to help out with the more "advanced" projects. That's what friends are for, right?

Thank you for all your help so far! The bonfire sounds wonderful! Would've been nice the last few nights around here - finally starting to feel like Autumn!!!