Moisture test how long?

[Mustangjim]

I am getting ready epoxy paint my new concrete floor. I saw some posts about doing a moisture test. I duct taped down a 6 mil garbage bag, about 2'x2'. How long should I let it go before checking? The floor is 2 1/2 months old.

Thanks, Jim

 

[Winmon]

24 hours will do it....Good luck!

 

[JBL]

FWIW I had mine taped down for over a week and saw nothing. I utilized clear plastic so that I could see it without taking it up. Despite this and the manufacturer puttin g the floor down for me I have blistering. Caveat emptor. If in doubt have it polished!

 

[Winmon]

Mine also passed the moisture test (which I did twice) and I have blistering. I am in the process now to see if I can fix it.

 

[bmwpower]

Just curious...did either of you guys put down a vapor barrier under the slab? I wondering if the water "comes and goes" with the weather and maybe you tested on a dry day? I dunno...

 

[Winmon]

I have a vapor barrier under the slab. I have now heard of several guys who have experienced the moisture blisters with a vapor barrier installed. I am thinking (hoping) my moisture may be due to either A) When I removed the sealer, the concrete was then able to "breath" so the moisture was able to now escape. I put the epoxy down about 2 weeks after I stripped the sealer. Maybe I should have waited the normal 30-35 days the concrete curing takes.
Or B) I used a pressure washer to rinse during the cleaning and etching process and maybe the pressure washer got water into the pores of the concrete. I had the nozzle set on the highest pressure setting instead of the "fanned out" setting of the spray. I was really trying to make sure I got all the cleaning and etching residue off. I gave the floor a full day to dry. Maybe I should have given it more time then that.

 

[boiler7904]

I taped clear plastic to my slab in a couple of areas at 11:00 on a Friday night and let it sit until early afternoon on Sunday. No moisture. I cleaned my slab in this order:

- Scraped construction adhesive and drywall compond and dry swept entire floor.
- Vacuumed entire floor.
- Washed with 4:1 ratio of water and simple green. Let dry while I ate dinner
- Washed entire slab with 4:1 ratio of water and muriatic acid. Garage slab is split into 4 quadrants. Each quadrant was washed twice and rinsed 4 or 5 times.
- Rinsed entire slab and squegeed to remove standing water.
- Rinsed entire slab and vacuumed to remove all water.
- Let dry from Sunday evening until the following Friday night when I filled divots with filler. The first coat of EpoxyShield Pro went down on Saturday morning.

I didn't use a high pressure setting on my hose nozzle. Instead, I used a setting meant to flood the surface. Volume of water is more important than pressure when trying to dilute and neutralize the acid.

I'll have to wait and see how things turn out since I just put the clear down today. I'm staying off of the floor now until this friday when I'll start moving stuff back in.

 

[Mustangjim]

Well I let it go 48 hours and it passed. I was nervous because I do not have a vapor barrier. I also have a high water table. About a week after I poured the floor I put a piece of OSB in the corner to put my lawn mower on just in case it leaked oil, I didn't want it to stain the new floor. I moved the OSB a couple weeks later and there was a dark spot where moisture obviously was stuck under the OSB. The dark spot has mostly faded, hopefully once I paint it won't be seen.

I bought the Rustoleum Professional epoxy in the 5 gallon bucket (not 5 gallons of paint). The label says it should cover 500 sq. ft. Is that fairly accuract or should I buy more? Is one coat enough?

Thanks, Jim

 

[boiler7904]

I bought the Rustoleum Professional epoxy in the 5 gallon bucket (not 5 gallons of paint). The label says it should cover 500 sq. ft. Is that fairly accuract or should I buy more? Is one coat enough?

Thanks, Jim

Depends. How big is your garage? I bought the Rustoleum Professional in the two gallon kit (boxed). I want to say that it said it would cover 300-400 square feet. My garage is 420 square feet. I used a Wooseter epoxy safe roller with 1/4" nap to apply the epoxy. I had about an inch or so of material left in a five gallon bucket when it was all said and done. I would have probably had less left if I had used 3/8" rollers like they suggest.

For the clear, they say one kit will cover 500 square feet of a floor that has the epoxy on it. I would say that's accurate based on the fact that I had a little left over when I finished my floor.

 

[Winmon]

there was a dark spot where moisture obviously was stuck under the OSB

I hate to say it, but that is a bad sign.

The label says it should cover 500 sq. ft. Is that fairly accuract or should I buy more? Is one coat enough?

My Rustoleum went farther then advertised, and I put it on thick. I also bought it in the 2 Gal. Kit. I would recommend putting down 2 coats. The 1st coat does not look nearly as nice as the 2nd coat does. The 1st coat looks alot like a primer.