Do I Need Primer To Paint Concrete? (12 Questions Answered)

I’ve just finished painting the concrete floor in our new workshop – and boy should I have done more research first. It turns out I didn’t use enough primer and the whole thing took ages to get right with four topcoats of garage paint.

You should always seal concrete and masonry floors with primer before painting them. The primer acts as a bond between the concrete surface and the paint, making sure it sticks properly to create an even, durable and long-lasting finish.

Let’s consider this topic in more detail, and discover how to use primer correctly when painting concrete floors – so you don’t make the same mistakes I did…

Do I Need Primer To Paint Concrete?

Can You Paint Straight Onto Concrete?

Well you can – but not if you want your paint to stick. We’d always recommend using a proper primer before you start painting. This may make the job a longer one, but trust us, it’s worth it. You’ll get a long-lasting effect that won’t peel or crack, and will look fantastic.

What type of primer do you need? An acrylic primer bonds well to concrete and gives you a great painting surface. If you’re working outdoors, try a silane penetrating sealer, which is water-resistant.

For a heavy-duty finish (if you’re painting a floor in a commercial area, for example, use a tougher primer like an epoxy. Finally, if the area you’re painting is messy and stained, a PU (polyurethane) primer will help to get the tricky surface ready for that first coat of paint.

Do You Need Primer Before Masonry Paint?

Yes, you do need to seal and prime masonry before you start painting. It’s a porous surface, so the paint will take far better if the masonry has been printed first, even when you’re using the perfect type of paint.

Masonry paint has two roles: it has to make the exterior of your house, garage, garden wall, or outbuilding look fantastic. Even more importantly, it serves to protect the brick, concrete, or plaster from the elements. So, it’s super-important that you don’t cut corners when painting the masonry. 

What Happens If You Paint Concrete Without a Primer?

We’ve heard lots of scare stories about what happens if you paint concrete without first having primed it. The job of the primer is to get the surface ready to take the paint.

Without this step, the paint may not adhere to the concrete, so you won’t get that lovely, lasting finish. Primer is the bonding agent between the surface and the paint, making sure that the paint stays on the concrete.

You won’t get that smooth effect if you skip the primer stage, either. It evens out blemishes and fills cracks, and can help a poor surface become the perfect base for the paint. In short: if you don’t use primer, the paint won’t look as good, and probably won’t last very long.

How Do You Get Paint To Stick To Concrete?

Concrete doesn’t naturally take paint very well, which is why you need to use a primer first. The layer of primer acts as a bond between the concrete surface and the paint, making sure it adheres.

It can even be used to help the concrete accept a paint that isn’t actually meant for concrete (although we’d still always recommend using a proper masonry paint).

Is Painting Concrete a Good Idea?

Yes, it certainly is. Concrete is easy to use, cheap, plentiful, strong, durable, long-lasting… but one thing it doesn’t tend to be is pretty. A lick of paint can make all the difference to the appearance of a concrete floor or wall.

Whether you’re painting your new backyard boundary in a fetching shade, or want to give your basement a livelier look, painting concrete is a great way to transform it.

Paint also masks stains and marks on concrete surfaces, and helps to prevent any further damage. A properly primed and painted concrete surface is tougher and more mark-proof than an unpainted one.

How Do You Prep Concrete For Priming?

Of course, before you brush on that primer, you need to prep the concrete surface first. Here are the simple steps you need to take to get the concrete ready for the primer:

  1. Remove any old paint from the concrete. This is a pressure washer job if it’s outside, or a good old wire brush for indoor projects
  2. Give it a good clean with something that removes dirt and stains. Trisodium phosphate will work, but you may prefer to use something more eco-friendly, like Krud Kutter’s products
  3. And there’s another stage before the primer – the sealer. Because concrete is so porous, it needs a sealer before it will take the primer. This is essential for indoor jobs, otherwise moisture can seep into the concrete.
  4. And finally, you can prime… Yes, we appreciate it’s a long-winded job, but it will definitely be worth it!
Painting concrete floor

Is There a Spray Paint For Concrete?

You can get spray paint for concrete, by trusted spray paint experts Rust-Oleum. It’s great for painting fiddly areas (it gets used a lot for garden statues), although it’s not really a cost-effective option for large surfaces.

What Paint Is Best For Concrete?

In general, you need masonry paint for concrete surfaces. Before heading off to Home Depot or Lowe’s, have a good think about what you need the paint to do as there are different types of concrete or masonry paint.

Does it need to be waterproof or water-resistant? Is it for the floor or walls? If the former, does it need to be slip-resistant? Will you have to clean it? Could it fade in the elements? How easy is it to apply? And of course, what color do you want?

Pick up the sealer and primer at the same time. There are different varieties for indoor and outdoor use, and an epoxy-based primer is the best for heavy-duty use (such as in commercial premises).

How Long Does Painted Concrete Last?

We’ve read that it generally lasts up to 5 years before you need to paint your concrete again. This is if it’s been correctly prepped, primed, and painted. If it hasn’t, you may see signs of flaking pretty soon after painting…

Most concrete paints will show how long it should last on the tin or in the manufacturer’s instructions. Generally, the better the quality of the paint, the longer it should last (of course, there’s a financial element to this…).

When it’s time to repaint, we’d suggest sanding back the old paint and starting again. You’ll get a much better result, and hopefully five more years of a beautifully painted concrete wall or floor. Because the surface has been protected by the paint, at least you won’t have grease or dirt stains to deal with… 

Can You Paint Concrete Without Etching?

Etching concrete is the process of applying an acid (such as hydrochloric acid) to the concrete then rinsing it off, in order to create a better surface for painting. As you can imagine, this isn’t regarded as good practice these days, but you can get eco-friendly versions from brands like Rust-Oleum.

The primer or paint needs a surface it can adhere to, and this etching stage certainly creates this, by making the concrete rougher and easier to stick to. Is it essential? The jury’s out on this one.

Is It Better To Paint Or Stain Concrete?

Neither is better than the other: it depends on what effect you want. Painting your concrete walls or floor will give you a more solid color. It’s a great look if you want a striking effect, and you get a great choice of shades.

Staining is more subtle. You’ll get a more translucent effect, but it really soaks into the porous concrete for a lasting effect. It’s not the best approach if the concrete is stained or messy looking, as it doesn’t mask imperfections in the same way that paint does. However, it won’t flake like paint can eventually, so arguably, it could look tidier in the long run.

Do I Need To Prime My Garage Floor Before Painting?

Yes, you need to prime any type of concrete before painting, otherwise the paint won’t adhere as well to the surface. This is true of a garage floor, which will take some heavy-duty impact, so will need to be tough.

You could use an epoxy primer for its reliable robustness, as a garage floor is such a hard-working area. If the surface is stained with oil and grease, a PU primer is the best choice. Take a look at this short film about prepping and painting a concrete garage floor (and we love that Aussie accent…). 

So, as you might have guessed by now, our response to any question about priming before painting concrete is yes, do it! You’ll get a better looking and longer-lasting finish, and while it will make the project longer as you have to apply the primer than wait for it to dry and cure thoroughly, it really is worth the extra effort.

Summary

I’m finally happy with the job I’ve done on the concrete floor in our workshop – but I wish I’d saved days of time by properly applying the primer first.

I’m quite impulsive sometimes and all that prepping seems like overkill, however, it really does make sense to correctly prepare the concrete floor space first before you get down to painting.

Oh well – we live and learn! Best of luck with your floor painting. 🙂