Filling contraction Joint

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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?
Thanks,
R
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Roanin wrote:

Don't ask. Look at the buckets of stuff for the word "Latex."
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Go back to the flooring store and ask again.
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Roanin wrote:

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 joint).
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.
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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. -----
- gpsman
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On 7/5/2012 9:17 PM, Roanin wrote:

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.
John
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Those all have a "joint" periodically to allow for the movement of the floor as it varies with temperature changes. The OP didn't say where his floor was located so we are all guessing at best here.
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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 require gluing.
R
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Roanin wrote:

You're worried about the cut-lines showing through a vinyl floor put down inside a pole barn?
A kitchenette?
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?
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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.
R
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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 up quicker.
R

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wrote:

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.
--Vic
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On Sat, 07 Jul 2012 18:43:06 -0500, Vic Smith

suggestion, but you need a "backer rod" to stop the PL from dissapearing. A jute cord might work, or a foam "spline" as used for mounting screen in aluminum frames.
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snipped-for-privacy@snyder.on.ca wrote:

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.
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snipped-for-privacy@snyder.on.ca wrote:

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 work.
But, then again, who knows?
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HB-
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 tensioned.
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.
cheers Bob
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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 foreclosure...
structural engineer said if they decide to replace the ceramic tile to se that material......
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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.
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Roanin wrote:

25 feet *between* cuts?
How much vinyl are you putting down?

Is that the small tube (300 ml) ?
Even a small tube should get you at least 10 feet if the cut is 1/8" wide and 3/4" deep.
Something doesn't sound right.
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Guy at Home wrote:

Barn is 40 x 60 and cuts are about 1/4" wide

12 x 12

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 concerned about.
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