I am going to put some cushioned vinyl flooring on a concrete slab that has
saw cut contraction joints in it. What should I use to fill these joints so
they will remain a bit flexible, yet be firm enough to support the flooring
so the joint does not show through. The flooring store told me to go to HD
and get something that mixes with a Latex additive. No one there knows what
I am talking about. Any suggestions?
LePage Construction Adhesive (PL Premium).
Squeeze it into the joint, use a plastic trowel to smooth it, then after
24 hours go over it with some rough sand paper (because it tends to
expand when it cures). Don't get the stuff on your skin (it's a bitch
to clean off). It looks like caramel when it's being squeezed out of
the caulking gun.
It will be about as hard as plastic when it's cured (but with some small
air bubbles in it) - so over time it won't sag and form a crease that
you will see through the vinyl.
If you use anything else that's softer (like a latex or silicone calk)
it will be too soft and the edges of the concrete will form a crease
that you will eventually see through the vinyl.
The PL-Premium won't affect the functionality of the saw-cut joint in
the concrete (the joints are not meant to allow the concrete to flex
along the cut - they're meant to allow the concrete to BREAK along the
If this concrete was poured with the intent to cover it with vinyl then
there was really no reason to put cut-joints in it in the first place.
I just read something about this the other day, regarding driveways.
They recommended strips of wood.
I knew that wouldn't work in my joints, they're too rough, so I moved
on and didn't make note of the details or where I was reading it.
Might work for you.
There is a powdered cement crack filler, off hand I can't recall the
name. It appears to be made of powdered plastic and cement. Mix it with
a bit of water and trowel it into the crack. Next day sand it smooth and
level. It may take two coats to get it perfect as it will slump a little
while drying. It makes a *lot* of dust when sanded so use a mask. I
filled some cracks in my basement slab before painting years ago and the
cracks haven't reopened. In fact with care you can make them totally
disappear. A belt sander (medium to fine grit) in one hand and shop vac
hose pulled along in the other make quick work of smoothing the surface
while keeping the dust at bay.
Using a concrete caulking will work but getting it smooth is very
difficult and it doesn't sand well, if at all.
The room is in a pole barn. Finished a room, insulated it real well and now
my wife wants a kitchenette in it. the room has heating and cooling in it,
however HVAC will only be used when the room is in use. I plan to just put
the vinyl down and only glue one edge as the cabinets will be on the other
three sides. Appreciate all the suggestions, but only one person has
indicated a specific product to use. I know all about why the joint is there
and how it works, I just need to know what to put in them. They do have
cracks in the bottom of them now but they are pretty stable and not heaving
of cross cracking. The vinyl I am using is a cushioned vinyl that does not
You're worried about the cut-lines showing through a vinyl floor put
down inside a pole barn?
Are you kidding?
Is the housing and mortgage situation so bad in the US that people are
having to convert their garages and out-buildings into homes?
I gave you an answer (PL-Premium).
If the cut-lines are wider than 1/4" then you should probably use mortar
mix (leveling compound is unecessarily expensive for this use).
And - are these really cut-lines, or are they expansion joints?
NO I'm not kidding. Who the hell are you to make a judgment call on what I
do with my money. And all I know is that when they laid the floor a week or
so later, the came back with a saw and made cuts about 1/2 to 3/4" deep
about every 25 feet or so apart.
Additionally, thanks for the PL premium tip, I was considering that from the
beginning but did not know how it would work.
FYI, tried the PL and it just is not going to work. I only got about 3' out
of a 10oz tube. Then it sank down and looks like it just seeped through the
cracks in the joint. Wonder about a Bondo polyester product which will set
Just use mortar. It's made for this. If you don't have pointing
tools, or the cracks are too narrow, first mix a thin batch to pour in
the cracks, then a normal batch and use a putty knife to smooth it.
I don't get it.
The OP says the joints are cut down to 1/2 or 3/4". I would assume a
1/8" concrete disk made the cut.
Yet he claims he only gets 3 ft out of a (small?) tube of PL. A small
tube ought to go a lot further than that.
If the gap doesn't extend completely through the concrete, I don't see how
it can be an "expansion" joint. It could be a "separation joint," that is,
giving the slab a place to crack if necessary. Sort of like scoring a piece
of glass prior to breaking.
If the latter, filling the crack with anything, including cement, would
But, then again, who knows?
Good point..... partial depth cuts are NOT for expansion, they are
crack controll cuts.
Concrete is gonna crack unless you;re very lucky or the stab is post
The cut "encourages" the crack to occur in the cut so as to provide
visually pleasing results.
Your suggestion of a cementiuos filler makes sense.
when putting down ceramic tile theres a product used, kinda a plastic
open weave clothe that prevents cracking into the ceramic tile.
a family member bought a home with a slap crack that went across the
house. kinda unslightly, but home was cheap saved big bucks buying a
structural engineer said if they decide to replace the ceramic tile to
se that material......
Good idea. I assume you're talking about the stuff that's a heavier version of
the nylon mesh tape used for sheetrock joints. It's used to "tape over" the
joints in Hardi-Backer, too.
The question is whether to try to hold everything together or let it move.
With ceramic tile, there isn't much choice - it's not going to move (without
cracking). If the surface has some give (vinyl, for example), I'd be tempted
to use an elastomeric filler.
I figure it settled down through the cracks in the bottom of the cuts. Maybe
Bondo will work, it stays a bit pliable and sets up a lot faster and can be
sanded even to the edges. I only have to fill about 20 feet in the area I am
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