How should I clean concrete balcony walls before painting?

Question

I have a huge balcony which has concrete walls on either end, and on the front balcony wall. My balcony is as wide as my living room and I see the balcony very clearly from the LR, DR & kitchen areas. The concrete walls need to be painted. Hasn't been done for six years. Paint has cracked & chipped in areas.Balcony ledges need some repairs too.What is the best & easiest method for a DIY to clean the concrete walls before I paint? Can anyone advise me the best cleaning solution to buy? Should I use a wire brush for washing the concrete? The walls are soiled from rain and soil and just being exposed to the elements, especially during the winter months. HELP! I need help please. Thanks!

Answer 1

Use a cup of laundry soap, a gallon of bleach and 3 tablespoons of TSP (tri sodium Phosphate) the TSP will keep the mildew off the wall for a longer period of time. Using a powerwasher will save your back, trust me. Concrete walls, don't pit as much as most think they do, so power wash away. Any small imperfection on a concrete wall will be fixed when you get the new paint on. Before you paint, use a concrete primer. It is thick, but it will bond to the concrete and the paint will bond to the primer. Seems thats the issue you have, they never primed. Paint without primer will not stick, it will cover but never truely stick, hense the peeling. Good luck

Answer 2

How To Clean Concrete Walls

Answer 3

If you do not have a power washer, rent one.
Use a mixture of bleach and water. About 1 gal bleach to 4 gal water.

Spray the concrete and wash down with clear water. Let set for a few minutes. Repeat if necessary. You can increase the pressure to remove any chipped paint. Be careful with the pressure, it can pit the concrete necessitating more repair.
You can use a wire brush if needed.
Any bleach/water that falls below, spray with clear water to wash away. That ratio with more water will not hurt plants/grass.
Make any necessary repairs and paint.

Professionals often use bleach and claim some magical ingredient. Had a friend who did this for a living.

Run clear water through the power washer to clean out the bleach, before returning.

Answer 4

Good thinking, when painting concrete know this. The paint will come off. What you want to do is control the damage. One error made by unprofessional concrete cleaners everywhere is that they only wash. If you do this, dust, dirt, etc. may turn into mud in very small trace amount. It is necessary(if you want high quality) to sweep, wash, and rinse, preferably with a high pressure hose. I'm not entirely sure, but I wouldn't use a strong acid. One could eat away deeper and lighter in different places of your concrete and make much more of it ready to come off. I would use a base, and maybe a light acid(rinsed off immediately after placed on) right before. Remember that concrete can absorb moisture and let it dry before painting. You might have known all of this but i hope it helps. -B

Answer 5

The best thing i can tell you to do is to rent a pressure washer. we have done it to our front porch and it workd great.