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Unread 03-13-2007, 08:00 AM   #2
Chris the Rep
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Join Date: Aug 2004
Posts: 705
Expansion Joint Caulk

Sorry for the delay, sometimes things come up. Here is my long winded response, probably more than you ever wanted to know on the subject.

The urethane referred to for expansion joints is a type of caulk. It's usually in the caulk aisle, but I have seen it in the professional contractors section of some stores, or it'll be near the concrete stuff. Urethane caulk suitable for floors will be marked with minimum Shore A Hardness 35, which denotes traffic grade sealant. You may find it in large 30 oz. cartridges, which are usually pourable/self-leveling versions.

Unfortunately, your chances of finding it in anything close to a red are pretty unlikely. Limestone or gray are pretty much the standard colors available in traffic grade sealants.

Now, if you're willing to venture beyond the local big box store, you can probably get a urethane in a red color. There are two part urethane caulks available in almost any color you want. Some manufacturers will even color match for you, never hurts to ask. The supplier carries the main unit, (base and catalyst) and stocks color packs for the most common colors. They can usually can get a color pack for unique colors on short notice. (A color pack is usually about 4-8 oz. of a special pigment that is added when the whole thing is mixed up.) Typically, these units are one and a half gallons of mixed material. You have to mix the whole unit at once, there is no measuring out partial units. A unit this size will probably do a couple hundred feet of joints that measure 1/4" x 1/4".

My local yellow pages has a heading "Caulking Materials and Equipment". You can also check under "Contractors Equipment and Supplies", or "Concrete Accessories". Sometimes ready mix concrete suppliers carry these sealants. Wherever you get the caulk will also carry the backer rod you'll need. Between the yellow pages and the web, you shoudn't have any trouble finding a source of supply.

The "compressible backing strip" is more commonly called backer rod. It is usually in the the caulk aisle as well, sold in a small coil in a bag. It's kind of like a foam rope that is put into the joint so you don't use too much caulk. There are different diameters available, and two types.

There is open cell foam, often called "denver foam, and is a lot like the foam used in a furniture cushion. If you can stuff a 1" diameter piece of denver foam into a 1/4" joint, it'll work fine. Open cell works great for indoor use, and if you cut it or tear it while your installing it, it won't matter. Open cell foam will wick water, so it is usually used indoors and occasionally on vertical applications.

Closed cell foam does the same thing, but is a little more unforgiving when you install it. The "closed cells" contain nitrogen gas, and if you pierce the cells and then caulk, the gas works it's way to the surface and causes bubbles in the surface of the caulk. The same thing happens of you try to compress too large a diameter rod into a joint too small. Buy closed cell foam close to the size of your joint as possible. Closed cell foam won't wick water, so it is often used on horizontal surfaces. If the caulk is damaged, the closed cell foam acts as a secondary water stop. You want to make sure that you have backer rod in every gap where you're going to pour in sealant, other wise the sealant will flow through or beyond any gaps. And it's a real PITA to clean up if it goes where you don't want it to go.

Why go through all this?

1. You can probably get the color you want.

2. You can get this caulk in a pourable, self leveling formula, which will go in a lot faster, and will cure a lot faster than a gun grade material. Install the backer rod, mask all of the joints, mix the caulk, pour it into the joints. Tooling is a lot easier and faster too. To make pouring easier and more precise, bend a small coffee can to create a spout, and pour from that. I think that's a lot easier than crawling around with a caulking gun.

3. You'll get a joint that is tough enough for a shopping mall floor that will last many years without tearing or shrinking, in a color you wanted, not one you settled for.

Some of the brand names you might look for are Tremco, Vulkem, Sonneborn, Sika, or Bostik Chem-Calk. They're all good ones.

Ok, I'm done.


Last edited by Tiger Mountain Tile Inc; 11-28-2016 at 12:06 PM. Reason: remove dead links
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