View Full Version : pre-epoxy prep: filling a control or expansion joint


gotta56forme
08-28-2008, 04:35 PM
I'm doing the preplanning for my Rustoleum Pro epoxy floor. I have cuts in my concrete that are less then 1/4 inch wide, that a Rustoleum tech support person said is a 'control' joint, not an expansion joint. I asked what I should fill them with prior to the epoxy floor and he said not to fill them. I understand why they are there, but I should be able to fill them with a flexible material... yes/no? I've read numerous threads here and saw the PL self levelling material associated with a Rustoleum floor. Should I feel confident using that in my 'control' joints?

Question #2: If I can fill the joints with something like the PL product, do I want to do it the last thing I do before applying the epoxy?

Thanks in advance for the info...

Scott/Gotta56forme

akdiesel
08-29-2008, 05:01 AM
Would the reason you want to fill the cuts for asthetic reasons?
Personely I feel they are there for a reason. Maybe using a flexible filler might do the trick but it could be water run off as well.
I am not sure what the difference is between a "Control Joint" or an "Expansion Joint" or if there is a difference.

gotta56forme
08-29-2008, 11:29 AM
Both for aesthetic reasons and so I don't have to clean junk out of the cracks. My joints already have cracks in the bottom of them, so I'm thinking they may have already done their job. Also, I'm not talking about using a rigid filler but a flexible filler that I can epoxy over.

JoelS
08-29-2008, 11:55 AM
you'll need some "backer rod", which is foam product that you can push down into the crack with a thin bladed tool. just leave it about 1/8 from the surface and then caulk the remaining smaller void with flexible concrete caulking. without the backer rod, the caulk will just drip down into the crack

ansehnlich1
08-29-2008, 03:21 PM
you'll need some "backer rod", which is foam product that you can push down into the crack with a thin bladed tool. just leave it about 1/8 from the surface and then caulk the remaining smaller void with flexible concrete caulking. without the backer rod, the caulk will just drip down into the crack

I have the same size control joints in my garage. When I epoxy my floor I am going to fill the joints AFTER I lay the epoxy with a color match caulk.

PoorOwner
08-29-2008, 09:14 PM
I used GE extreme silicone XST to fill my joints afterwards. But it is paintable so you could do be before the epoxy. It stops ants from coming up and also if I spill some fluid it does not go into the ground below the slab. Mine was 1" wide in some spots and I used backer rod as needed, make sure you tool it really nice with alcohol as lube because I didn't know how to do it back then, and the rough finish trap in alot of dirt working on cars.

1/4" will be very easy to tool so you get a nice smooth look especially if you paint over the caulk, not all silicones are paintable so choose carefully but I am sure you will be fine with this product.

WolverineCoatings
08-30-2008, 09:55 AM
ALWAYS ALWAYS ALWAYS... Ask the manufacturer of the product you intend to use! Some cheaper products can not handle the expansion and contraction of a filled joint. If you want a smooth (monolithic) floor without cuts/control joints/expansion joints in it, you'll have to choose a system where the coating can handle the filled joint expansion and contraction. OR, fill it (after the floor is coated) from time to time (depending on the abuse you give it) with a cheap caulk material. I would NOT recommend using ANY caulk below the coating that the manufacturer does not say is compatible with the coating you are using!

'the epoxy floor guy'
08-30-2008, 11:31 AM
I 100% Agree with filling in the control joints and coating them.

A few points:

#1 NEVER use a silicone BASED product they are NOT well suited for concrete. use a GOOD urethane caulk. What ever you use make sure it is PAINTABLE.

#2 Make sure your 'filler' is CURED before you coat it. Most caulks will state the paintable in (x) hours.

#3 There are some Epoxy 'flexible' coating products available that are two part POURABLE that will fill the joint, remain flexible, and be 'hard' enough to stand up to some abuse.

I see floors with a GREAT epoxy coating then leave the UGLY, Dirt filled 'cracks' untreated.:headscrat

#3 option I have sources for product, NOT cheap but IMO the best solution.