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Concrete Wall Repairs & Concrete Epoxy

Concrete Wall Repair Cements & Epoxies

The rain was pouring. It had been doing it for several days. However, at this particular moment, it was torrential rain. I was in the basement of a little house I had purchased. It needed some work and I thought I could fix it up and make a small profit.

I went into the basement to check on something and water was squirting out of a crack in the wall. Not only that, water was shooting four inches high up from a crack in the floor! I was panic stricken.

The house was in the middle of a hillside. Massive quantities of water were flowing above and beneath the surface of the ground. Needless to say, I had my work cut out for me.

Patching Cracks

Cracks in concrete or concrete block walls are very frustrating. I believe this is so, because both building materials represent permanence. It isn't unreasonable for these materials to possibly last 50 to 100 years. Cracks, however, transmit a failure sign. What's more, if the crack actually widens, it is a sign of a big problem. Soil movement, poor soil, or faulty design may cause expensive repairs to be undertaken.

Crack Repair Products

Years ago cement companies developed products that have the ability to fill cracks in concrete and block walls. These products worked so well that they were able to resist a hydrostatic head or the weight of a water column. These special cements expand as they dry. In contrast, ordinary Portland cement shrinks as it dries.

If you are willing to put a little work into a repair job, these materials are very effective at stopping leaks. The trick is to chisel the correct profile in the crack. You need to undercut the crack. This means that the the crack would look like a dovetail joint in a drawer when viewed from the side.

Making the crack into a simple V shape is the worst thing to do. As the special cement dries, it actually pushes itself out of the crack!

Super Glue!

Yes, there are glues for concrete. In fact there are many different types. You can bond old concrete to new concrete, old to old, and new to new. This is done by using special concrete epoxies.

These glues are similar to any standard household epoxies. However, they are formulated with special chemistry that allows them to bond to the concrete and withstand any chemical attack from the alkaline chemicals in the concrete itself. Some of these epoxies have tremendous strength characteristics. They can actually 'weld' concrete back together in certain situations.

These epoxies can be applied by serious DIY'rs or applied by professionals. Here in Cincinnati, there are several companies that will inject epoxies into cracked walls. They will even offer lifetime warranties in certain cases.

Brush - On Compounds

You have probably seen commercials about magic brush-on compounds that will make your wall leak problems disappear. Well, that may take some black magic! There are numerous brush-on waterproofing compounds in the marketplace. I have used many of them. In certain instances they can stop water. However, most manufacturers insist that they be applied on the side of the wall where the leak originates. This can be a tall order to fill, as often this requires an enormous amount of digging. In some instances it may be nearly impossible to excavate one side of a wall.

Furthermore, these compounds rarely have any give. If the wall crack opens or moves, the brush-on compound will crack.

On many of my jobs, we did successfully apply it to the inside of a basement wall or the outside of a retaining wall with great success. I'm convinced that this success was directly related to following the directions on the label.

Surface preparation is critical. Wall surfaces need to be squeaky clean and moist. The thickness of each coat needs to be closely monitored. Apply too much and it can pull itself from the wall. Often people want to glob it on a wall. Two thinner coats usually work much better than one thick coat.

These products also can be used as a decoration. If you are artistic, create a texture!

Column B119

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11 Responses to Concrete Wall Repairs & Concrete Epoxy

  1. we bought a house built in 1917 water comes into the basement starting about half way down the basement wall. there are some cracks in the joints of the block but are more like hair line cracks. would epoxy work to fill them by just brushing it on.

  2. I have a crack in a concrete block retaining wall, probably due to the settling of the soil. What is an easy and maybe not expensive way to deal with this problem?

  3. Hi, i bought my house about a year ago and notice that the basement does get damp at certain times in the year, heavy rains, spring and sometimes fall but overall not bad, also the house is over 100 and the original foundation was stone and brick, and i am not sure when but they poured about a foot and a half of cement around on the inside about 5 feet high (the total hight is 6 so i have about a foot of rock and brick that i see), now the cement walls are starting to have a little water come through. I was told there is no way to dig the outside without it crumbling the old rock and brick, but the cement needs to be repaired from the outside....any suggestions?

    • JT, your question requires lots of typing, plus I have some questions for you so I can give you the correct answer(s). I only do pithy answers here in the comment section. If you want to protect the investment you have in your house and not waste time or money *hoping* you make the right decision, you should talk to me on the phone for just 15 minutes. It'll be the best investment you've ever made in your home!

  4. WE ADDED A ADDITION ONTO OUR HOUSE WHICH INCLUDED A BASEMENT. THE JOINT BETWEEN THE OLD BASEMENT CONCRETE WALL AND THE NEW CONCRETE WALL HAS A GAP THAT A PIECE OF PAPER CAN SLIDE THRU. WHAT DO I NEED TO SEAL THIS GAP. THANKS, DOUG

  5. my house is being effected with damp ness in the external walls in this connection you are requested to which chemical is useful to apply for pressure grouting how to get solution to my problem to clear from dampness of walls.

  6. We have recently brought a new house around 50 years old which has cement rendered walls both outside and in. There is a several cracks where the floor meets the wall in the corner which is now leaking. What would be the best the product to fix this issue?

  7. 'In 2005 the previous owners said a guy patched leaking cracks in the basement's poured foundation with something he called "RTB". Does anyone know what that is? Can't find it on t...'

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