Filling In The Joints In A Concrete Block Wall

Let me suggest the following site, http://www.woodmagazine.com/ may be better informed to answer your question.

Ron,

They seem to be 100% wood oriented and my application is concrete block. Am I missing something?

Bruce

It seems reasonable that if you take the block down to bare surface, you could mix some quickcrete and fill them in. I used quickcrete to rebuild a block wall that had been hit by a car (not hard). I had to do a little at a time but it adhered pretty well.

If you're feeling brave, you could just go DYI stucco. Not a whole lot more work on block than filling the grooves would be.

http://vagrantviking.com/stucco.htm

Are there any reasons to use three coats (scratch, brown, final) other than thickness and strength? If stucco is being applied to block that is pretty smooth then why couldn't a single coat (over bonding agent) be used?

Hold on there just a second. The blocks are painted already?

Everything I just told you was for bare block..........including the little stucco link. Forget it if they're painted.

After washing, prime it with this. After that, get yourself some good elastomeric caulk. All available at Lowes or Home Depot. The reason for that particular primer, is that you're probably dealing with lead paint..........regular primers won't stick, and will peel. That is a good one.

Apply a bead of elastomeric caulk in the joints, (latex), not getting too far ahead of yourself. Get a bucket of water and a few of these to smooth out the caulk. After it cures, apply finish paint.

That stucco method won't work on a painted wall either, however, there are stucco textured elastomeric paints. They will provide a texture to your wall, but, it is difficult to get a uniform finish.

Thank you.

Yes, they have been painted many times. With the Florida sun breaking down the paint the block will look bare after pressure washing but the deep pores will still have paint in them and the joints usually tend to hold a little paint too.

Well, it won't cost much to do a test with either method. At this point, if you're just looking to make the joints less noticeable, I'd go with the caulk............with old paint still on it here and there, and temperature extremes, I think anything with concrete in it is going to end up separating and cracking from the joints.

With the caulking method, you can also come back and fill low spots with no problem, and, after curing, take a 60 grit sanding disc, fold it in half and use it to knock down any high spots.

[you're probably dealing with lead paint] Is pressure washing lead paint going to pose a hazard? and might it be illegal?

Maybe in some places. Lead paint is another one of those things that have been regulated to death. Don't grind it up and breath it, and don't eat it, and you'll be fine.

It's always struck me as funny that lead paint has been so demonized, while at the same time, any 12 year old kid can walk into Walmart and purchase a handful of pure lead fishing weights with no problem.

Thank you. That sounds good.

Even with a good pressure washing my 50 year old blocks will have some of 50 years worth of paint remaining and therefore they will not be as porous as new block. With a little luck my joints will blend in pretty well. I am surprised at how well the joints disappear in the one area on the back of the house where someone filled a few of them.

If I make them look better then that will be good enough for now. After I replace all the windows and do a remodel I can spring for a professional stucco job.

I have very little experience with concrete and tile. At their deepest I would probably only be adding 1/4" of thinset. With the Florida sun getting pretty hot this time of year do I really need several weeks of cure time before painting?

Thank you,

Bruce

Try to keep the thinset moist by misting it during the curing process for about 4 or 5 days. Use the polymer modified version of thinset. You really don't want to have the sun dry it out too fast. The hot sun is not good for the curing. It needs to cure slowly to attain full strength and bond. The suggestion to paint a bonding agent on the joints is worthwhile.

Thank you.

Thank you. I have never used "leveling concrete" and I had included it because I was taking a guess that it would stick better. It is helpful to know that it is not a good choice.

Hi Bruce

In S.A. we mostly build with blocks and there is a product we use for filling chased electrical channels. Clean an roughen your surfaces properly using good old sugar soap, you could even chip the surface with a small chisel. Dry the area thoroughly with a hair dryer, the additional heat will speed up the dying process, then just spray this http://building.dow.com/na/en/products/sealants/biggapfiller.htm

Allow it to set then just sand down and paint. It's waterproof and paint adheres to it perfectly

Barry

Thank you,

Bruce

You have some good information already but I would add... On block walls along the starter course (bottom row) you'll see almost no mortar between the joints. This is by design. The idea is should there be a load placed on either side of the wall there will be a place so water can escape and relieve pressure. You DON'T want to fill these.

What you're looking for is a vinyl skimcoat cement. Quickcrete, available at most hardware and Do-It-Yourself home repair shops, makes a great edition for small cracks and skim-coating. I used some almost twenty years ago, and it's still intact. The secret, as always, is a clean, damp surface. Use a small amount at a time because it starts to set in about 30-minutes. You'll like the results.

Tom

clean joints with high pressure only using water.

after dripping of apply with a paint brush a mixture of portland cement and water, the mixture must be as thick as paint, this will "burn in" your concrete joints for a better bonding.Let it set till its almost dryed up.

Make your cement mixture, 1 volume part portland cement, 2 volume parts sand, 1/4 volume part of mortar chalk (keeps the cement flexible) and of course water,The mixture should be as thick as toothpaste.

Fill your joints with this mixture, let it dry as far as: you can barely push your fingerprint in it, then use a sponge and a lot of water making circulair movements on your jounts, until you get the right smoothness, then use a spatel to make it straight, when neccesary repeat the last actions.

While it is drying keep the joints moisture by adding a verry thin waterspray on the surface.(cement hardening/drying is a chemical process, adding water will only slow the process avoiding cracks)

When your concrete bloks are verry dry, let it soak up enough water while you clean the bloks, when the bloks are to dry they will saok up to much water out of your filling, ending up in cracks in your joints while drying.

good luck

senor bruce

buenas tardes from Mexico. Iam an Architect by degree, have a company that

builds industrial buildings, industrial plants. look into a product named KRYTON

www.kryton.com

very good wterproofing product, mixes well with concrete mix. never worry again

on water penetration, mildue, excelent product, " try it" on a sample area

2x2 feet. then see results.

saludos from Mexico ARQ RAUL S VILLARREAL MONTERREY, NUEVO LEON, MEXICO