Okay, I know this is probably a stupid question with an obvious
answer, but...How do I tell if my concrete basement floor is level or
not? It's not so bad that it's obviously wavy, but I don't want to
plan on finishing the basement with an engineered wood floor only to
find out that it's slightly out of level. I've heard as little as 10
mm over a 3m length will cause problems, but I am not sure how to
detect this amount of dip or rise. Thanks for any help!
On Thu, 11 Oct 2007 13:41:43 -0700, firstname.lastname@example.org wrote:
Level or flat?
For level, fill the room full of water and measure the depth at
For flat use a long straight edge that you have verified is straight
by putting it against something else that is flat.
Okay, thanks to everyone for the advice. What I'm really after I
think is that it's flat. I don't actually want it level, since it
currently slopes a little down toward the sump pump, which I think is
The concrete is 10 years old, and even with the super heavy rain
storms this past year, we have NO water in the basement. The original
owners installed a "Tuff-N-Dri" waterproofing system, including a
"Warm-N-Dri insulating foam on the outside of the poured concrete
walls, so even they aren't really as cold in the winter as some
basement walls I've felt. So I'm fairly confident that the basement
will remain dry, unless our water heater blows up.
So, basically I want to put down engineered hardwood flooring (DIY, I
hope). My plan is to put down the Delta-FL underlayment, then the
moisture/sound barrier, then the flooring. I figure the Delta-FL will
do double-duty, one as insurance against some water eventually coming
in (or from the water heater in case of catastrophe), and it should
help make the end floor not so "hard". Several people have noted
that the Delta-FL makes the floor "softer", more like a framed
Anyway, in reading forums on this, several people have mentioned
needing to level the floor with leveling compound, but all those posts
seem to indicate a visibly uneven floor, whereas mine looks pretty
good to the naked eye, even putting my face to the floor and
scanning. But I'll take the advice here and try a bowling ball,
marble, and water test. If anyone has any other advice based on this
new info I've provided (on the even-ness of the floor or otherwise),
it is all very much appreciated.
On Oct 11, 4:41 pm, email@example.com wrote:
Concrete specs frequently call out for (I'll let you do the
conversions) the slab to be level within 1/8" within 10'. That's
what's spec'd, not necessarily what they give you. That flat of a
slab in a residential basement would be a minor miracle.
The easiest thing to do is to plan on patching the floor with
compound. You can use a straightedge, say 6' or so, to locate the low
spots. Then use self-leveling compound which pours on like soup and
seeks its own level - you'll want to feather out the edges and move
quickly. If you use a regular floor patching compound you can use the
same straightedge as a screed to level off the patching compound.
Make sure you wipe off the edge of the screed frequently. You may
have to use latex bonding agent before applying the level compound
depending on what's on the slab now.
You should also insure that you have a dry basement, and still take
precautions against moisture wicking up through the slab. Verify that
your intended flooring is approved for below grade installations. A
significant number of them are not.
The flooring won't care if it's level or not, within reason. It
does need to be sound, dry, and flat. If you can't see a
significant problem with a 8-10ft straight edge, or a ball,
or water, you're unlikely to have any issues.
Since this is a basement, you need to pay attention to the
moisture issues. Is it dry now? If not, correct that problem
before installing a floor. Include a moisture barrier and
follow ALL of the manufacturer's recommendations during the
actual installation of the floor.
Oh, and I assume this concrete floor is "mature" and fully
cured. If this is newly poured concrete there are quite a
few additional issues to consider.
| Malcolm Hoar "The more I practice, the luckier I get". |
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