Best way to flatten concrete walls outside of my house?

Submitted by Remy4409 t3_10oj6ym in DIY

Hi! I've looked many places, some say that you need a special concrete grinder, some say that an angle grinder can do the job, I wanted some opinions.

https://imgur.com/a/XNUlfrz

My foundation is made out of poured concrete. It's 60 years old, and back then they used 2x6s to pour the concrete, making it look like blocks, but it's not.

It will get waterproofing redone, drain and isolation this summer for the underground part. I wanted to grind, patch a bit the holes and paint back the rest. I'd like to grind the lines and make it as flat as I can.

Not looking for polished concrete or a perfect job, just wanted to remove this "block" looking pattern.

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Quallityoverquantity t1_j6g6dfe wrote

This is 100% not worth the time and the incredible amount of effort it would take. Do not attempt this idea

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HarlanCulpepper t1_j6f40p0 wrote

I saw the pictures and honestly don't see what the big deal is - unless you have money to burn and maybe a slight case of OCD?

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Remy4409 OP t1_j6fk7fq wrote

Yeah mostly, it's mostly personnal preference. I'm a first year home owner and I learned tons of stuff, I want to do it just to learn stuff.

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Quallityoverquantity t1_j6g63ao wrote

You won't be learning anything besides there are countless other things that are a better use of your time and effort.

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tackle_bones t1_j6i5wh9 wrote

Listen, you shouldn’t be getting downvoted for this. I am in a similar boat, and I just redid the surfaces and edges of a two-step concrete entrance to my back door. Similarly, I wanted to learn concrete repair, and I had some time while I was trying to figure out a different project on the house. It’s good you’re trying to learn.

That said, what others are saying here is true. The amount of effort it took me to even remove the paint and previous epoxy from what… 10 sq ft?… was freaking exorbitant. Grinding, chiseling, grinding again, chiseling again… it’s like… back breaking. It will take you way more time than you can reasonably anticipate or justify. And you have to do it if you at all want to actually repair the concrete. In your case, it might make more sense to use specific paints or epoxies that can be used on top of other coatings (i.e., the current paint) in order to smooth out some areas you don’t like. Do your research though and make sure you aren’t making bigger headaches for yourself.

If you in fact plan on repairing certain areas of concrete, I’d be happy to talk you through that. I’m pretty happy with my recent repairs and feel pretty confident now with the products to use.

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Ragidandy t1_j6ggqdl wrote

Yeah man, learning that way is the best. Just make sure you wear a mask. Grinding concrete sucks, but breathing it is worse.

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CharlotteBadger t1_j6jfmas wrote

And if it was painted before the 70s, very likely there’s lead in the paint, which will now be scattered into the ground around your house, and into your lungs if you’re not masked.

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Zomunieo t1_j6ggk0m wrote

You can get silicosis from a project like this. The lung damage is permanent and no joke.

Don’t do it. But if you do a job this size, get a respirator that covers your entire face, preferably with an oxygen tank.

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ADHDengineer t1_j6gn05x wrote

This is going to be the worst job you’ve ever signed up for. Don’t do it.

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GamerGER t1_j6f20p1 wrote

I used an angle grinder with a diamond grinding disk to flatten out an old wall but the concrete parts are tough and take some time.

You could also add a layer of mineral plaster to get a new texture and even out the pattern. Or a combination of both ;)

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Remy4409 OP t1_j6f2czd wrote

Thanks! Not a bad idea, but I should sand everything down anyway to remove the paint first, as it would not allow anything to stick correctly, so a combination of both would be best.

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VerbingNoun3 t1_j6gm0cr wrote

If your going the grinder route have someone lightly pouring water over it the whole time. Dont breathe the dust!

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GamerGER t1_j6f4r54 wrote

Yeah paint removal is probably necessary to get proper bounding of the layers. Maybe there is some kind of primer but that is dependent on the used paint.

For reference I used something the like of this: https://www.amazon.de/PRODIAMANT-Diamant-Schleiftopf-doppelreihig-Diamantschleiftopf-PDX829-025/dp/B00ECWRMRQ/ref=sxin_21_pa_sp_phone_search_thematic_sspa?content-id=amzn1.sym.b3c099a2-7e6a-4a1a-a4ce-a6664d93a79f%3Aamzn1.sym.b3c099a2-7e6a-4a1a-a4ce-a6664d93a79f&crid=31H826ZLPVMNE&cv_ct_cx=scheibe+f%C3%BCr+beton+glatt+schleifen&keywords=scheibe+f%C3%BCr+beton+glatt+schleifen&pd_rd_i=B00ECWRMRQ&pd_rd_r=1f678aa0-59d1-4cff-a672-ab42d2d97de4&pd_rd_w=mqj65&pd_rd_wg=IiuxU&pf_rd_p=b3c099a2-7e6a-4a1a-a4ce-a6664d93a79f&pf_rd_r=7D02EYS1CFND0XQB39S8&qid=1675030594&sprefix=Glatt+scheibe+%2Caps%2C147&sr=1-1-6e6ea531-5af4-4866-af75-1ef299d1c279-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9waG9uZV9zZWFyY2hfdGhlbWF0aWM&psc=1&smid=AHP4NSCWH5R9U

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g_st_lt t1_j6fos3b wrote

This may not be permissible in your area, but it seems like it would be much easier to add something to the concrete than to grind the concrete flat. In some of those pictures, it's not just seams, there are significant depth differences.

This is an incredibly silly idea.

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codyish t1_j6gkuem wrote

Others have said it but I'll agree - this is almost certainly not worth the effort. You'll have to put in a lot of effort to avoid inhaling fine concrete dust at best or lead at worst and the only thing you'll learn is that concrete that old is incredibly hard and that jobs like this eat through grinding wheels and are incredibly hard on your elbows, shoulders, and ears.

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didntfindmyfeet t1_j6fncll wrote

Do a lead test first please! If you grind that or sand blast that paint away the lead will be in your dirt on your feet. If there are little kids around it will get in their mouths and on their hands on their feet and then into their blood. Lead will be everywhere for a long time. Box stores have the tests.

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jeffersonairmattress t1_j6f706g wrote

Form fins? Knock them down with a diamond cup wheel in a 7” angle grinder. You will kill a 5” grinder and a 9” is too heavy to hump around a vertical wall. Get a LOT of tarps and have it wet sandblasted if you want a quality finish on it. Unless the paint has lead in it, in which case do nothing but encapsulate with a shellac-containing primer and paint. Do not grind or sand yourself if it contains lead.

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chicagoandy t1_j6gopfw wrote

That would not be worth the cost or effort to be.

Surely there are more important areas to spend your money or time?

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shifty_coder t1_j6hxk09 wrote

Fix the water and drainage issues, and then pay a mason or concrete worker to skim coat the foundation. Then just paint after, if you want.

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LetsBeKindly t1_j6j2rav wrote

You want to grind on your 60 year old foundation for aesthetic reasons?

Bro, go remodel the bathroom. Or the bedroom. Or finish the attic.

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zachariahd1 t1_j6fji2w wrote

Foundation plaster

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Remy4409 OP t1_j6flyhj wrote

Yeah, but I still have to strip the paint.

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zachariahd1 t1_j6fm3r2 wrote

Not it you roll on a concrete bonder first

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ifihadanickel t1_j6gogv5 wrote

You could try filling the gaps with some acrylic mortar repair sealant then painting over em.

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Larryloose t1_j6haf77 wrote

grind the high spots of then change the grinding blade for a wire brush attachment. Get all the paint off. Then you can parge the entire foundation with a cement sand finish float it off with a damp sponge and it will look beautiful.

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tackle_bones t1_j6i69zh wrote

And he’ll finish paying off his mortgage just in time to enjoy the fruits of his labor lol

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jimjamjahaa t1_j6hg55d wrote

hmmm you could angle grind some lines in to the concrete to create a key for a render to go on top. i think that would be 900 times easier than grinding it flat.

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Animade t1_j6j7gfb wrote

there is a machine u can rent that people prep epoxy garage floors with that shoots metal bb's at the concrete and vacuums up the dust. and I've personally just used an angle grinder with a diamond cup wheel for small jobs.

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Monkeybomber t1_j6jarot wrote

An angle grinder with a masonry grinding disc will do what you're looking for. Wear a P100 breathing apparatus and glasses. Silicosis from breathing in the dust will have you die drowning in your lungs own fluid.

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trippybike t1_j6k1m0h wrote

This sounds like something I would do... And I do lots of things that end of wasting huge amounts of time. Like many other people have said, this would suck to do and should probably be avoided.

Anyways, if you must do this, a high quality respirator is a must. You also must do something to control the dust. Even though it's outside this is critical to avoid putting yourself and others at risk. If you've never done this sort of work then you can't possibly understand how much dust it'll produce. You can't just wear a respirator while working. Unless you're very lucky with the weather, the dust will stick around and blow all over the place when it's windy. This could last days or weeks after the job is done.

You can grind dry with a pretty serious dust collection system or you can wet grind with a pneumatic grinder or a very well insulated electric grinder. I prefer the former, but if you must use the electric grinder to wet grind then plugging it into a GFCI outlet is essential...

But you really don't want to do this... If you just don't like the lines, maybe you could stucco the whole thing instead, I really don't know about that though.

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SpruceGoose133 t1_j6l78d6 wrote

I'd leave it alone. But if you want to change, I'd get a diamond cup grinder and grind away at the paint on the block edges. You might need to wash it with a muriatic acid to help with adhesion. Or maybe there might be a product to act as a primer to help with the bonding do a Google search.. Then I'd apply cement on the seems with a trowel. I'm just a gerry rigger but I think this should work fine. run it by a concreate pro. Probably paint it in a couple of days so it doesn't dry to fast.

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