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I want to paint a large external brick wall. The building is around 55 years old and the mortar between the bricks has recently been deteriorating fast due to excessive rain and wind, hence letting rainwater seep through the wall.

I am wondering what the most effective way of painting the wall is. Should I use brush, roller, sprayer, or a combination of them? I know this can be a matter of opinion but each method has its pros and cons that make it hard for me to decide. Spraying is relatively fast but the paint does not seem to penetrate the surface well. Rolling leaves a nice finish but works best on the surface of the bricks and not the mortar. Brushing is arduous and does not usually lead to a great finish.

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    Before you paint, fix the pointing between the bricks. If you paint without fixing, you're just hiding the problem.
    – FreeMan
    Mar 29 at 11:22
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    I'm no mason, but I'm going to say "no". You don't see silicone sealant used in the initial construction, so I'd venture a guess that it shouldn't be necessary in properly done repairs either. I'd wait for others more experienced than I to chime in.
    – FreeMan
    Mar 29 at 12:39
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    I would spray first because it's so efficient at delivering the paint to the surface, then back roll with a roller to get the finish you want and maybe penetrate better. Work a section at a time or it will dry before you have a chance to backroll. As we all know, a successful, long lasting paint job is all about preparation, make sure it's clean and as @FreeMan said, repair any damaged mortar between the bricks (pointing is masons terms). Mar 29 at 13:07
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    Frankly, fix the pointing and leave the brick. Unless you really don’t like the look of brick. Otherwise the paint becomes yet another maintenance item.
    – Jon Custer
    Mar 29 at 14:37
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    Painted brick invariably looks horrid. Please don't do that. Just fix the actual problem (re-pointing the mortar) Mar 29 at 17:00

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Paint on brick is a disaster. You need to fix the pointing, that's normal maintenance for masonry, and paint is not that, nor will paint replace that.

If you paint, you will be dealing with peeling paint until you or the next person finally sandblasts (or soda-blasts) the paint off. That can damage the surface of the brick (soda, less so,) but even damaged brick is less annoying to deal with than painted brick. The most you should even contemplate (and not rush into - there are cons as well as pros) would be a clear sealer / water repellent.

But you still need to fix the pointing first, and that's probably all you really need to fix, done properly. Loose and crumbling mortar is raked out of the joints, and fresh mortar is placed/packed in the joints, and properly dressed (shaped. Partly appearance, partly shedding water properly.)

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  • I do appreciate the advice. How about rendering the wall? I have fixed the pointing at numerous locations over the years. However, rainwater reinforced by strong sideways winds still manages to eat away/pulverize/crack more and more sections of the mortar, create new gaps, and seep through the wall. It is an ongoing annoyance. Wasps, bees, ants, and other creepy-crawlies also slowly but steadily damage the mortar.
    – Reza
    Mar 30 at 1:09
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    Sounds like it's been piecemeal pointing - and it sounds like the whole wall needs to be repointed. I'll let somone who's more familiar with rendering as a wall treatment tackle that option in a new answer - unless "render is stucco" and I'm not sure it is from my visits to the UK, it's uncommon in my part of the world, and I lack experience of it. I strongly suspect that not fully repointing will make the wall a poor base for it, but I don't know...
    – Ecnerwal
    Mar 30 at 1:15

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