Waterproofing of garage floor — concrete petroleum stain Ask MetaFilter

Waterproofing of garage floor

Impermeabilization/Waterproofing of a garage concrete floor. I have seen garages covered with goey smelly petroleum based substances that couldn’t be properly cleaned as the substanced penetrated somehow into the floor (guess it’s years of percolation ?). What paintable product could I apply. Please try referring to a specific kind-of-product rather then a brand.

What you want is an one part epoxy floor paint. Readily available at the soulless big box vendor near you in the paint section.

posted by Mitheral at 5:16 AM on September 30, 2005

Note that if you are already dealing with oil stains, epoxy paint won’t really be able to grab, and you’ll need to deal with them first. If the slab is new and fully cured, then epoxy paint is A) exactly the right answer and B) nasty as hell. Wear the right protective gear — namely, a true fliter mask, not a dust mask, with the right filters installed.

Ideally, you want the concrete as clean and dry as possible — the winner day to paint is Saturday after no rain and lower humidity for a few days.

Most paints, including these, don’t cure well in the cold. So, if you’re in the 40s already, you may want to boot the job until Spring, and use tarps and/or trays to keep the garage until then. Read the directions, follow them carefully — epoxies are miracles when used properly, and sticky, smelly messes when used improperly. By the way, forget cleaning brushes — buy the 2nd cheapest rollers and brushes, and toss them (the absolute cheapest won’t last long enough to do a good job.)

Finally, if you already know where the wear spots are, double the coatings there, unless the paint says don’t do that.

posted by eriko at 5:44 AM on September 30, 2005

I used the Rustoleum product on my garage floor. Pain in the rear to put down, but is now beautiful and easy to clean.

As an alternative to epoxies, you may want to consider a custom installed tile floor. One of my neighbors is a car guy, and has a showroom type floor. The durability is amazing, and the looks are great. It’s at least as durable as the epoxy, and probably much more.

One caveat is that I have no idea what it cost.

YMMV.

KFJ

posted by kungfujoe at 6:23 AM on September 30, 2005

eriko writes nasty as hell. Wear the right protective gear — namely, a true fliter mask, not a dust mask, with the right filters installed.

Water based epoxys are both a lot less smelly and also go on thinner allowing more of the traction properties of the concrete to come thru. I don’t remember the stuff I used being worse than a low VOC oil paint.

posted by Mitheral at 6:50 AM on September 30, 2005

You might want to throw down some sand, lest the floor be too slippery. I found a really, really badly-formatted but informative page about epoxy floor finishes —they’re selling a specific product (that I can’t vouch for (or against)), but the advice looks good.

posted by MrMoonPie at 8:36 AM on September 30, 2005

Elpapacito, you didn’t actually say what your goal was: to cover up an already messed up floor, or to waterproof it. Which are you after?

For waterproofing, the going wisdom (here in the rainy Northwestern United States anyway) is that applying a product to the concrete won’t actually solve your waterproofing problem. It will simply transform it into a water pressure or treatment failure problem. For waterproofing, the best idea seems to be interior perimeter drains. Not really a do it yourself job unless you like using a jackhammer, but very reliable.

posted by daver at 8:42 AM on September 30, 2005

The floor is six months old concrete, -2 underground level with just a little dust over it. The place is abundantly drained around all the perimeter and heavily vented as it’s the floor closer to earth ; indeed all the 2nd box have a big venting opening that I manage to shield with a perforate plastic sheet so that rain/sand particle don’t enter the box yet air is able to circulate almost freely.

Basically my point is trying to do preventive maintenance and conservation work.

Oddly enough Goop and other similar hand cleaners will remove (to a degree) oil stains on concrete.

When I painted the floor of my recently-made woodshop, it involved cleaning off mineral deposits with muriatic acid, hosing down, drying, priming, then painting. It took two days. The big box stores have all in one kits, but I found it more cost effective to get the individual components. You will definitely need to clean your floor with the acid.

It’s made to handle the evils that a garage offers, and so far it’s done a fantastic job. I’m sure there are competitive products, but I’m a fan of garage tiles.

As for cost, I paid about $4/sq. ft.

Step 1: Muratic Acid + Power Wash

Step 2: Sherwin Williams Tile-Clad Epoxy (2 part system, available in water based iirc)

good suggestions above on the throw-away rollers!

the stuff is a bit pricey, but far superior to big box store coatings. If you have a friend who is a contractor they can get you a substantial discount over retail. if you don’t have a contractor friend, just ask for a discount @ the store. You may want to look for one of the sherwin williams commercial stores to purchase. the one by the mall may only have a limited supply and no 5 gallon pails of this stuff.

full disclosure: i worked at a paint store 15 years ago :)

posted by freq at 1:50 PM on September 30, 2005

Very good answer, I wish to thank you all for clearing up my ideas and offering interesting advice.

So from what I can understand it seems to me:

1. I must de-grease my concrete well, to insure a good cohesion..even if my concrete is quite new even a mild degreasing will help

2. I could find benefit from using water based epoxy as my experience lying down thick epoxies is = 0. I hypotize the more viscous the more problems I’ll have to face..so maybe two layers of thin-water epoxy will forgive me more then one layer of thicker epox

A third problem occourred to me while reading: could it be a good idea to leave part of the concrete exposed so that it’s allowed to transpire. I hypothize my concrete is sitting on compressed earth (?) or on some kind of foundation. but it is certainly a layer that is subject to more water then the -1 layer..I was wondering, maybe coating only a portion of my floor could be more beneficial then coating all of my floor..so that some perspiration still occours. am I making nonsense hypothesis ?

It is fairly likely the concrete slab is set on a thick layer of gravel, which allows for evaporation, and some actual water flow (like a hard rain.) It’s the standard way of doing it. The slab should breathe from the bottom, not the top.

Thank you all guys for your help !

Waterproofing of garage floor

Impermeabilization/Waterproofing of a garage concrete floor. I have seen garages covered with goey smelly petroleum based substances that couldn’t be properly cleaned as the substanced penetrated somehow into the floor (guess it’s years of percolation ?). What paintable product could I apply. Please try referring to a specific kind-of-product rather then a brand.

What you want is an one part epoxy floor paint. Readily available at the soulless big box vendor near you in the paint section.

posted by Mitheral at 5:16 AM on September 30, 2005

Note that if you are already dealing with oil stains, epoxy paint won’t really be able to grab, and you’ll need to deal with them first. If the slab is new and fully cured, then epoxy paint is A) exactly the right answer and B) nasty as hell. Wear the right protective gear — namely, a true fliter mask, not a dust mask, with the right filters installed.

Ideally, you want the concrete as clean and dry as possible — the winner day to paint is Saturday after no rain and lower humidity for a few days.

Most paints, including these, don’t cure well in the cold. So, if you’re in the 40s already, you may want to boot the job until Spring, and use tarps and/or trays to keep the garage until then. Read the directions, follow them carefully — epoxies are miracles when used properly, and sticky, smelly messes when used improperly. By the way, forget cleaning brushes — buy the 2nd cheapest rollers and brushes, and toss them (the absolute cheapest won’t last long enough to do a good job.)

Finally, if you already know where the wear spots are, double the coatings there, unless the paint says don’t do that.

posted by eriko at 5:44 AM on September 30, 2005

I used the Rustoleum product on my garage floor. Pain in the rear to put down, but is now beautiful and easy to clean.

As an alternative to epoxies, you may want to consider a custom installed tile floor. One of my neighbors is a car guy, and has a showroom type floor. The durability is amazing, and the looks are great. It’s at least as durable as the epoxy, and probably much more.

One caveat is that I have no idea what it cost.

YMMV.

KFJ

posted by kungfujoe at 6:23 AM on September 30, 2005

eriko writes nasty as hell. Wear the right protective gear — namely, a true fliter mask, not a dust mask, with the right filters installed.

Water based epoxys are both a lot less smelly and also go on thinner allowing more of the traction properties of the concrete to come thru. I don’t remember the stuff I used being worse than a low VOC oil paint.

posted by Mitheral at 6:50 AM on September 30, 2005

You might want to throw down some sand, lest the floor be too slippery. I found a really, really badly-formatted but informative page about epoxy floor finishes —they’re selling a specific product (that I can’t vouch for (or against)), but the advice looks good.

posted by MrMoonPie at 8:36 AM on September 30, 2005

Elpapacito, you didn’t actually say what your goal was: to cover up an already messed up floor, or to waterproof it. Which are you after?

For waterproofing, the going wisdom (here in the rainy Northwestern United States anyway) is that applying a product to the concrete won’t actually solve your waterproofing problem. It will simply transform it into a water pressure or treatment failure problem. For waterproofing, the best idea seems to be interior perimeter drains. Not really a do it yourself job unless you like using a jackhammer, but very reliable.

posted by daver at 8:42 AM on September 30, 2005

The floor is six months old concrete, -2 underground level with just a little dust over it. The place is abundantly drained around all the perimeter and heavily vented as it’s the floor closer to earth ; indeed all the 2nd box have a big venting opening that I manage to shield with a perforate plastic sheet so that rain/sand particle don’t enter the box yet air is able to circulate almost freely.

Basically my point is trying to do preventive maintenance and conservation work.

Oddly enough Goop and other similar hand cleaners will remove (to a degree) oil stains on concrete.

When I painted the floor of my recently-made woodshop, it involved cleaning off mineral deposits with muriatic acid, hosing down, drying, priming, then painting. It took two days. The big box stores have all in one kits, but I found it more cost effective to get the individual components. You will definitely need to clean your floor with the acid.

It’s made to handle the evils that a garage offers, and so far it’s done a fantastic job. I’m sure there are competitive products, but I’m a fan of garage tiles.

As for cost, I paid about $4/sq. ft.

Step 1: Muratic Acid + Power Wash

Step 2: Sherwin Williams Tile-Clad Epoxy (2 part system, available in water based iirc)

good suggestions above on the throw-away rollers!

the stuff is a bit pricey, but far superior to big box store coatings. If you have a friend who is a contractor they can get you a substantial discount over retail. if you don’t have a contractor friend, just ask for a discount @ the store. You may want to look for one of the sherwin williams commercial stores to purchase. the one by the mall may only have a limited supply and no 5 gallon pails of this stuff.

full disclosure: i worked at a paint store 15 years ago :)

posted by freq at 1:50 PM on September 30, 2005

Very good answer, I wish to thank you all for clearing up my ideas and offering interesting advice.

So from what I can understand it seems to me:

1. I must de-grease my concrete well, to insure a good cohesion..even if my concrete is quite new even a mild degreasing will help

2. I could find benefit from using water based epoxy as my experience lying down thick epoxies is = 0. I hypotize the more viscous the more problems I’ll have to face..so maybe two layers of thin-water epoxy will forgive me more then one layer of thicker epox

A third problem occourred to me while reading: could it be a good idea to leave part of the concrete exposed so that it’s allowed to transpire. I hypothize my concrete is sitting on compressed earth (?) or on some kind of foundation. but it is certainly a layer that is subject to more water then the -1 layer..I was wondering, maybe coating only a portion of my floor could be more beneficial then coating all of my floor..so that some perspiration still occours. am I making nonsense hypothesis ?

It is fairly likely the concrete slab is set on a thick layer of gravel, which allows for evaporation, and some actual water flow (like a hard rain.) It’s the standard way of doing it. The slab should breathe from the bottom, not the top.

Thank you all guys for your help !


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