Chris Lewis wrote:
According to D K Woods :
wrote:
D K Woods wrote:

Chris Lewis wrote:

You're probably looking at several days for curing. Likely weeks
(or even months) before covering with wood flooring over fresh concrete.

Ugh.

Umm, AFAIK, this is untrue. Let it cure for a day or two and you could
throw down a vapor barrier and go to town.

Hi John,

Thanks for the second opinion. According to the Quikrete website the
'fast-settings' version should be good after 24 hours (and it even
mentioned that you can walk on it after 6!). But I figured that must be
a best-case-scenario for outdoors work. I'm sure being inside will slow
down the curing -- but weeks sounded a bit much.

Do realize that Quickrete's numbers are for setting of the material so
that you can walk on it. Ordinary concrete achieves about 95% of
its strength in a few days (less with quickset types), but the curing
process continues for much longer. Ie: a month.

Even longer still: concrete never stops curing, but the amount of
increased strength gets infintesimal after a while.

I'm referring to the amount of time you may need to wait before
_finishing_ the floor, not how long you need to wait to walk on it.

Take a look at the instructions for painting concrete and you'll see
what I mean.

Painting is another matter and you're quite right: you probaly should wait
a month for that. But laying a laminate floor atop the floor could be
done as soon as it's safe to walk on.

Fresh concrete is often a difficult surface to paint/bond to. Due to the
concrete itself (eg: base pH), and/or due to the the fact that concrete
continues to outgas moisture for a fair while while it finishes off
final cure.

The latter is _especially_ an issue with hardwood flooring.

Which is why you put down the vapor barrier, since you don't want the
water evaporating for good strength of the concrete.

The former is why you often have to use muriatic acid to prep concrete
for painting.

Of course, if Chris' goal was to frighten me away from the project, well
consider the warning heeded. It's looking more and more like something
that will be done sometime over the next few years instead of next few
weeks.

I didn't mean to do that. It just sounded like you had a generally
uneven (rather than spot-uneven) floor, where at least hearing what a
couple of contractors who actually _saw_ your situation would suggest
would help you decide what to do. If it's just a few square feet you
need to level, that's a different ballgame.

My remarks about long wait times is meant in this way: you get the floor/spots
releveled. You'll be able to _use_ the floor in a day or two at most. But
I recommend waiting a month or more before putting a floor covering on it.

If you're talking paint or stain, I'd agree, but laminate flooring should
be able to go down as soon as you can walk on it, provided you put down a
good vapor barrier to isolate the moisture.

But then I wouldn't bother with a cement fix at all, I'd do it with lumber
as I already suggested.



John
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