We are repainting a number of rooms in our home, do we need to put primer over the existing paint?

Are there any other gotchas that we need to prepare for before repainting the walls?


9 Answers 9


No, in general, you don't need to prime existing paint, but there are exceptions.

To prepare for repainting:

  • wash the wall to remove any grease.
  • fill any holes and cracks with suitable filler, possibly using flexible filler for longer cracks. Unless you're an expert you won't get the filler flush with the existing wall so you'll need a filler you can sand.
  • sand and prime the filled areas - priming will seal the filler and keep it in place. If there are a lot of filled areas, you might want to sand and possibly prime the whole wall to avoid a patchy look.
  • repaint the wall with at least two coats of your new colour.

If the cracks are large you might want to check there's not a current movement problem. New houses will settle quite a bit when first built and there'll even be some movement in older homes. If there is current movement then you'll be seeing new cracks appear and older cracks getting longer and/or wider.

If you are painting over a dark colour with a light colour you might need more than 2 coats to stop the previous colour showing through. If that's the case then using a primer or basic white matt emulsion for the first coat (or two if it's really dark) is a more cost effective option than using the more expensive coloured paint for all the coats. Unfortunately you don't always find that out in time.

Paint in full daylight - especially for the final coat - so you can see where you've been and be methodical.

  • 7
    I've found that priming can also help when going from dark to light colored paint.
    – Niall C.
    Aug 21, 2010 at 17:08
  • @Niall C. True - it's an extra layer of cheaper paint that'll help cover the dark paint up. I'll update the answer.
    – ChrisF
    Aug 21, 2010 at 17:09
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    If you fill holes/repair cracks, it's a good idea to prime the entire wall (not just patches). If you only prime the patched areas, you could end up with a splotchy looking finish.
    – Tester101
    Feb 8, 2012 at 17:16
  • 1
    A tinted primer when going from light to dark paint also seems to help. We put a thick forest green type color over a pale yellow in two rooms. The first was just painted over, took 4 coats! The second with a tinted primer coat took just 2 coats of paint. Feb 8, 2012 at 18:29
  • 1
    If there are stains on the wall, or if you're painting over a dark coloured paint it's best to prime the walls with a pigmented sealer/stain blocker undercoat first. This stops the existing paint showing through and means you will use less topcoat to get a good consistent colour.
    – hookenz
    Jul 28, 2013 at 20:57

If you want a really nice job, get a drywall pole sander and give the wall a quick going over with 200-250 grit paper before priming, and before your final colour coat.

Remember to wipe with a damp rag (use the pole sander if you like) before applying any paint/primer.

Drywall pole sander


Priming is best. If you have to do two coats of paint to cover the old color, why not use a good primer or primer/sealer and one coat of a good paint? Most people will say otherwise, but primer will stick to old paint a lot better than new paint will.

I recommend wiping the walls down with a damp cloth first, but it's a lot of work, and I've never done it to a wall that wasnt't obviously filthy.

Use one coat of primer and one coat of paint.

Never ask a paint to do a primer's job!

  • 3
    The problem is that one coat of the good paint may not be enough: the primer may shine through. Aug 23, 2010 at 18:26
  • 2
    Perhaps. Primer is usually clear or white. If it's white, a light color shouldn't give you any trouble. If the paint is decent, a dark color should be able to cover it as well. I guess the success depends on the paint color and quality. Worst-case, you need a second coat of paint- but many times, you won't.
    – nstenz
    Aug 24, 2010 at 20:32

There's one tip that was completely missed, and should have been at the start:

When painting over a surface that has had to be repaired or was very dirty (scrub it clean first), get both the paint and the primer tinted to the same color. As long as you buy the paint/primer in the same brand and they are both the same base, you will have exact match.

This one tiny little tip guarantees a perfect job with only one coat of primer and one coat of paint.


TSP and a sponge mop. Wash the walls once with a TSP solution, then again with clean water to remove any soapy residue. This stuff really works, so that means if you've sensitive skin, wear those big rubber cleaning gloves.

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You can mix some of your paint with the primer to tint it to the final color hue. This has always worked for me. This is a good method if the paint change is a drastic one.

  • 2
    In fact, you can get you primer tinted the same as your paint.
    – Matthew
    Feb 23, 2013 at 23:52

Ok. What I've found when transitioning from one wall color to another is not tinting the primer to the top coat but rather tinting the primer to neutral gray. I've done it both ways and, for some reason, (probably what parts of the spectrum gets reflected, what gets absorbed) the neutral gray (photographers among us, think 18% gray card...) allows fewer top coats. It seems counter-intuitive but, trust me, it works!


At Home Depot I always have them tint the primer the same color as the paint. They do that at no cost. Also after caulking or drywall repair is dry I paint those areas with one coat of paint or primer before starting on trim cut in work . When I paint body .It is dry. The paint is always blotchy if those areas haven't had an extra coat.


Personal experience about dark walls.

I painted a light yellow over a dark blue wall. I used Behr paint with primer added. After two coats the blue still showed through. Not sure if prior priming was necessary since paint contained it already. One of the walls was already white and one coat covered it up.

The third coat covered it up the last bits but what a pain.

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