Thirty years of paint/coatings experience has helped me to break down painting a garage/concrete floor into four simple questions:

1) How old is the floor?

2) Has the floor ever been painted before?

3) Is the garage a "working" garage or is it a basic "storage/car-park" garage?

4) Will you D-I-Y (Do It Yourself) or will you contract out the work?

Let's tackle these one at a time.

1) How old is the floor? If your floor has just been poured or it is less than 90 days old, bookmark this guide so you can come back to it after the 90 days have passed. Plenty of literature will tell you 28 days is sufficient but don't believe it. This short period only applies to the most ideal of conditions and it is rare, if ever, that a concrete garage floor has not been exposed to rapid or extreme changes of temperature and humidity within 28 days.

Simply stated, floors that are less than 90 days old are still green and as such are not fully cured. The Ph level (degree of alkalinity or acidity) of the concrete is far from balanced and any coating applied during this first 90 days will have a very short life expectancy; if you're lucky, maybe 6 months. Floors between 90 days and 10 years of age will likely require an etching with muriatic solution to balance the Ph level. Muriatic acid is commercially available and a mix ratio of 4:1 (a large paint pail with 1 gallon acid and 4 gallons water will do one standard garage bay) is a good strength to effectively etch your floor. (Note: If the floor is more than 6 years old, purchase a Ph Testing Kit as the floor may not require etching due to the conditions of your area. You are looking for a reading between 6-8, 7 being exactly neutral.)

Old floors will have a balanced Ph level and will probably only require a good cleaning. DO NOT USE SOAP! There are many commercial cleaners available that rinse clean and will not react with the paint you apply. A citrus cleaner, preferably one that is a degreaser as well, will give you excellent results.

2) Has the floor ever been painted before? It helps a great deal if you know the type of paint that is already on your floor. If you're not sure, the paint is still holding well and you don't want remove it, your options are limited as to what you can apply over it. Most latex (water-based) P/F (porch and floor) enamels will work well as they do not react with existing paints. Clean the floor well; if the existing paint has any shine, lightly sand it before starting. If you are aware of the type of paint, it's in reasonably good shape and  you don't want to remove it, repainting with the same type is logical. That is to say latex over latex, alkyd (oil-based) over alkyd and epoxy over epoxy.

When repainting a floor because the original coating is peeling, chipping or simply very worn, removal of the paint is crucial to the success of your new paint job. This can't be stressed enough, particularly when painting with epoxy. Epoxy floor coatings are tough and long-lasting which is why they are the common choice for most commercial concrete floors. Many large paint retailers have specialized divisions and/or stores that deal primarily with industrial coatings. These are the locations you would do well to seek out. They will have the expertise and familiarity with various situations and it is likely that whatever yours is, they've come across it before.

3) Is the garage a "working" garage or is it a basic "storage/car-park" garage? It is very easy to get caught up in high-end products available that claim to be the answer to all your problems. Garages that simply hold storage and cars with otherwise little or no activity don't necessarily require an expensive epoxy paint. Many P/F enamels available will provide a good, serviceable finish at a very reasonable cost. However, if your garage is regularly used for automotive maintenance and/or is a business facility, the choice of an epoxy coating is an intelligent one. There are several grades of epoxy coatings available and when the correct one is matched to the working/business environment, it will likely be roughly 5 years before any repainting is necessary.

4) Will you D-I-Y (Do It Yourself) or will you contract out the work? Any of the above coating choices can be handled by the home/business owner. With good advice from your local paint salesperson, you should be well-equipped to D-I-Y. Some, however, will prefer to have a commercial contractor handle the job. There are positives and negatives for both scenarios.

Your paint retailer may be able to provide you with the names of several contractors that handle this type of work but don't ask for recommendations for one over another. This would represent a conflict of interest to the retailer and is generally frowned upon by most companies, so check out any references available. A reputable contractor will readily provide you with references and an itemized quote for your job. Contractors generally charge per square foot and the price is conditional on several factors: physical size of the job, preparation required, travel time to and from the job site and type of coating chosen. Another factor may simply be how busy the market is due to the time of year or other circumstances. Contractors will have the necessary application supplies, knowledge of the procedure and be aware of the safety measures required. Some will allow you to visit their paint vendor and purchase the product yourself so that you may simultaneously choose the color; others will bring a color fan for you to choose from and handle all purchases themselves. D-I-Y means that you can choose when the job is done according to your own schedule; contractors will advise you when they are available, making it necessary for you to conform your schedule to fit theirs.

*** PLEASE NOTE THAT I HAVE MANY OTHER GUIDES THAT DEAL WITH PAINT AND PAINTING PROBLEMS --- SOME OF THESE MAY ANSWER QUESTIONS THAT ARE NOT SPECIFICALLY DEALT WITH HERE ***

***Pros/Cons for Different Floor Coatings***

Latex (Water-Based)

PROS

• easy to apply
• fast drying (usually 2 hours between coats)
• very low odor
• reasonably priced
• wide color range
• can be applied to a damp floor
• can be applied over existing paints
• water clean up

CONS

• short life expectancy
• light traffic/activity only
• minimum air temperature of 50F/10C required for application
• one coat application not recommended
• should not be washed/scrubbed within the first 30 days

Alkyd (Oil-Based)

PROS

• easy to apply
• mid-range odor only
• can be washed within days of application
• reasonably priced
• wide color range

CONS

• requires solvent (usually varsol) for clean up
• lacks flexibility; can chip
• floor must be bone-dry before application
• slower drying time (usually 6-8 hours between coats)
• cannot be safely applied over unknown paint types

Epoxy Floor Coating

PROS

• very hard finish 
• thick, long lasting paint film
• wide range of chemical resistance
• can be applied in one coat (2 coats recommended for commercial environments)
• wide color range
• available in different gloss levels (high/medium/low)

CONS

• more complex application; most products are 2 parts requiring measuring/mixing
• high odor; breathing respirators required for application
• high-end (expensive) product type
• requires special epoxy solvent for thinning and clean up
• some safety clothing/equipment recommended

Your local paint salesperson will be able to help you decide which coating is right for you. Be sure to get a contact name and phone number from your salesperson for any further questions, a copy of the product specifications and MSDS (material safety data sheets) at the time of purchase.

Best of luck with your project!