Friday, October 16, 2015

The Concrete Garage Floor: Tiles, Epoxy, or Sealing? Densifier and Penetrating Sealer.

The floor after densifier and penetrating sealer.

My garage floor is new 3000 PSI concrete and it is 4 months old.

I spent a lot of time trying to decide how to finish it and was helped by many people on the Garage Journal forum. I also got 3 quotes from respected local vendors.

Originally I had intended to merely spray the concrete with a densifier and to declare it done. But the garage remodel ended up being more extensive than I expected and the workers got overspray and drywall mud on the floor that needed to be at least cleaned off somehow for me to be happy.

Things I considered: Plastic tile (Racedeck), epoxy (various products, polyaspartic (HP Sparta-Flex), polishing and sealing (local vendor), densifier only, densifier and coating, densifier and penetrating sealer.

My requirements:
I want a coating to protect and seal the floor. Easy cleanup is desired. Non-slip is desired. maximum durability is desired. I like how cement looks, but am ok with coatings too. No special appearance is desired. No color or color chips.

I’m a motorcyclist and vintage car fan. I have a bunch of motorcycles and a motorcycle lift. Some of the bikes have worn, rusted and sharped edged center stands. I am not going to use pads to protect the floor from the stands or lift.

I am open to doing the work myself it is easy. I would much prefer to have a professional do the work if I can be confident of the quality of the results. But I would be upset if I paid a good amount to have the floor professionally coated and then to have it chip, crack, bubble, scrape off or otherwise fail.

Plastic tile:
I got a sample of RaceDeck and parked my 150cc vespa scooter on it. It scuffed the first time I parked on it. I continued to use it for 3 months and it looks like battle zone. Rejected.

Epoxy / Polyaspartic:
I really wanted this to work and I have good friends who swear by it. But I was really concerned it would scrape up. When the cement was 30 days old I called 3 epoxy vendors. One of the three seemed very knowledgable, did polyaspartic coating, had excellent yelp reviews, and said I should wait much longer before coating the floor. I waited 3 months and called him back. He said it was still early but he would come take a look. He put a meter on the floor and said it was still pretty wet: he said he could do it, but he would need to use a special primer. But then when he bid the job, next to the 15 year warrantee he hand wrote: “5 years for moisture”. Hmm, not encouraging. He also had a nice sample tile with the finish on it, and when I went to put the scooter on it, he said, “Oh, that will scratch it!” And it did immediately scrape the clear coat off the chips on the sample.

Then my buddy sent me some pictures of his 6 month old epoxy floor that he loves… and I saw a crack in the epoxy running all the way across the floor. I said, what’s that? Apparently he hadn’t noticed. I hadn’t realize that cracks might propagate through the epoxy. And given the floor is new, who knows how it will settle. There are some small cracks in it already. So, between the moisture concerns, center stand scraping and cracks: I rejected the epoxy / polyaspartic option.

(Note: If I was doing the epoxy myself for a modest price, I might be ok with some scraping and cracks. But for a $1800 pro installation on a 300 square foot floor, and concerns about moisture… ah... No.)

Polishing and Sealing:
I had a well known professional come and quote polishing and sealing the floor. This firm does many of the local restaurants and bars. I was concerned about this from the beginning, as a polish is really just a cosmetic process and it is fairly easy to mar polished concrete. So again, this ended up being about the top coating. I ended up having many of the same concerns about the clear top coating as I did about the epoxy coatings, as discussed above. I saw many beautiful surfaces in local restaurants with polished concrete floors, but I also saw many that were peeling and a mess. Additionally, the cost was high, at least from this vendor. But these discussions pushed me toward doing the floor myself.

Sealers and Coatings:
When I looked at sealers and coatings, I quickly learned that many sealers would not hold up to chemicals that I commonly spill in the garage. I want a sealer or coating to protect the floor. I definitely do not want to have to protect the sealer or coating from spills. So I learned to find the “chemical resistance” data sheet for the various products. Some coatings are great for resisting various chemicals, others are not. For me, resistance to gas, oil, alcohol, brake fluid and acetone were very important.

My Choice: Sanding, Densifier and Penetrating Sealer
At this point I decided I wanted to do the job myself, and I wanted to end up with a plain cement surface that would continue to breath and dry over the coming years. I still had the paint and drywall stains to deal with. Scotty of Legacy Industrial suggested renting a floor polisher and “screening” the floor. I decided I could try that.

I knew I would use a densifier after sanding as that would result is a stronger more dust free surface. But should I add a penetrating sealer top of that? Most of the penetrating sealers I found didn’t have a “chemical resistance” specification. I was very interested in Ghostshield Siloxa-Tek 8505, but that company could not provide any real chemical resistance test data.

I looked around and found that I could get the Prosoco Consolideck products locally and so I checked them out. Their tech support was excellent, and they have a product called “Concrete Protector” that is a penetrating sealer, allows vapor transmission (breathability). And the Consolideck Concrete Protector comes with this chemical resistance spec that looks very good to me. The one concern is that a penetrating sealer like this could make putting a future coating on the concrete more work (or perhaps even a problem) as they might impede the coating from adhering. But since I like the appearance of cement, I don’t think this will ever be a problem for me.

How I did it:
  • I bought a respirator mask. 
  • I rented a floor sander at home depot and bought a supply of 100 grit and 150 grit screens. (I tested the screens by hand earlier in the week with a drywall hand held sanding pad. On my steel troweled concrete they worked well.) 
  • I bought a new powerful wet dry/vacuum cleaner, a microfiber mop with several pads, a few 1 gal concrete/masonry pump spray jug. I heard the jugs were unreliable so I bought a couple with plans to return the extras. 
  • For my 300 square foot floor I bought 2 gallons of Consolideck LS (densifier) and 2 gallons of Consolideck Concrete Protector from a local distributer. (I ended up only needing less than a gallon of the Concrete Protector.)
Before Sanding:
Note the overspray and marks.

Day 1: Sanding
Note: I wore the respirator mask and safety glasses whenever sanding or vacuuming. There is a lot of dust generated in this process. Less gets in the air than you would expect, but you do need a good mask.

My floor is about 300 square feet and is divided into 4 quadrants of about 75 square feet each by the control joints. I went one quadrant at a time with the floor sander. For each quadrant I used a fresh screen. First I made 10 passes with a 100 screen. I’d stop and vacuum occasionally to see how it was going and I used a hand sander to to get tough spots of paint or drywall mud. I also changed direction by 90 degrees occasionally. Then I made 5 passes on each quadrant with a 150 screen (with a new screen for each quadrant). And finally I made two passes over the entire floor with the 150 screen.

After the sanding I vacuumed repeatedly and then my wife mopped with a dry microfiber mop and I vacuumed the dust she pushed up. It took quite an effort to get the floor mostly free of dust.

The result was a clean and nicely smooth, but not “polished floor”.
I’d guess this took me about 4 hours of cautious sanding and vacuuming.

Day 2: Apply Prosoco Consolideck LS Densifier
It was a hot day planned in San Diego so my wife and I got up early, watched some densifier application videos and got to it. It is important that it isn’t too hot as you don’t want the densifier to dry too quickly, you want it to have some time to be absorbed into the concrete. I sprayed and she mopped. We put on one fairly heavy coat of Prosoco Consolideck LS. This was absorbed fairly quickly (minutes) so when we finished we immediately started over and applied a second coat. This time the densifier covered better so we used less. It took longer to dry, the desired 5 to 10 minutes. There were a couple spots that seemed to pool a little bit and I lightly blotted them with a microfiber cloth to prevent too much of the chemical from puddling.
This took about an hour of spraying and mopping. The two coats used about 1.5 gallons of the Consolideck LS densifier.

Some pictures after the densifier dried:

Day 3: A day off and extra time for the densifier to completely dry

Day 4: Apply Consolideck Concrete Protector
Again, a hot day was forecast for San Diego, so we started early. I sprayed the Consolideck Concrete Protector and my wife mopped. We found the concrete to be less porous after the densifier and so we didn’t need too much, I’d call it a “medium light” coat. The Concrete protector needs to dry for an hour before putting on a second coat. After about an hour and 15 minutes the concrete was dry and we applied a second coat. The second coat really didn’t need much of the Concrete Protector and we applied it very lightly. A couple hours later the surface was dry, but the directions say the the concrete needs to be protected from water for 12 hours and that it takes 48 hours for the Concrete Protector to gain it’s oil resistant properties.
Not counting the drying time between coats, this took less than an hour to spray and mop. We only needed about 0.5 gallon of the Consolideck Concrete Protector and I was able to return the extra gallon that I had purchased.

Some pictures of the finished floor:

Things I learned:
  • The chemicals and stuff costs real money. I probably spent $300-400 on the chemicals, sander rental, sanding screens, mops, sprayer and other stuff. 
  • Sanding was easier than expected, but the floor sander was darn heavy (about 120 pounds) to load in my truck) 
  • I like the smooth floor that sanding created. All the little ridges and ripples from the steel troweling are gone. The floor is smooth but still high traction, it is *not* polished. 
  • Spraying and mopping was straight forward, but was best done with two people.