Basement Waterproofing with Epoxy Part 2A

September 15, 2014

Poured Concrete Foundation Waterproofing

This is number 2A of a 2 part series on basement repairs. In Part 1, we discussed waterproofing block wall foundations. In Part 2A shows how to identify leaks that need waterproofing in basement walls, and floors that are made out of poured concrete. Part 2B will deal with the actual repairs to poured concrete leaks.

In our last piece we discussed how many homes and businesses experience leaky basements year after year. The worse time is in the spring after winter accumulation of snow. There are a number of prudent things that you can do to improve drainage against your foundation like roof gutters, grading and improvement of drainage. The recommendations here do not replace that conventional wisdom. It is designed to augment and improve upon these conventional methods.

Identifying the Source of the Basement Water Leak

The nice thing about poured concrete is that it holds water back very well. The leak typically happens at a cold joint or in a crack or hole in the concrete.

Concrete Cold Joints

Fresh (plastic) concrete doesn’t bond to hardened concrete. The exception is when a special epoxy bonding agent like Epoxy.com Product #2007 – is used (this bonding agent will be discussed in a future article). When concrete has hardened or has started to harden and you pour more concrete against it (without the right bonding agent) you get what is called a cold joint. These cold joints are a common source of water leaks.

Virtually all basements are built with a giant cold joint – the cold joint between the floor and the wall. Typically there is some sort of water-stops material installed in these joints intended to stop leaking at this cold joint. These water-stops can fail. So the wall to floor joint in a concrete basement is a frequent source of water leaks.

You can also get cold joints in the middle of concrete walls and floors due to multiple pours. You can get cold joints if concrete is setting to fast and fresh concrete is poured against semi cured concrete. Sometimes saw cuts in the floor can be a source of leaks

Form Ties

Then there are the ties that go through the concrete to hold the forms together on either side during the pour. If these form ties are not installed perfectly or if the concrete is not totally vibrated around them, these ties can act as a conduit to let the water in.

 

Wall and Floor Cracks

When concrete cures it shrinks that is called “plastic shrinkage”. That plastic shrinkage can and usually does result in the concrete cracking. These cracks are one of the easiest ways for water to get into your basement. If the water makes it to the fill side of the tank (under the floor or against the wall) it will typically leak out into your basement. You should look carefully for these cracks when looking for potential leaks into your basement. If you are able to investigate into the water infiltration into your basement when it is leaking it will be easy to see. If trying to find the source of leaks when the basement is dry you have to look for water marks on either side of the cracks and beneath the areas that might be leaking.

Repairing the Basement Leaks with Epoxy

In the next installment on this topic, I will deal with how you waterproof the cracks while structurally repairing them with epoxy and similar materials.

For more information please contact me:

Norm Lambert
norm@epoxy.com
352-533-2167
www.epoxy.com

 


Basement Waterproofing with Epoxy

September 4, 2014

Many homes and businesses experience leaky basements year after year. The worse time is in the spring after winter accumulation of snow. There are a number of prudent things that you can do to improve drainage against your foundation like roof gutters, grading and improvement of drainage. The recommendations here do not replace that conventional wisdom. It is designed to augment and improve upon these conventional methods.

The following article will be 1 of 2. This one deals with Block wall foundations. The next one will deal with poured wall foundations.

Waterproofing Block Wall Foundations with Epoxy

One of the nicest features of most of our epoxies are that they are virtually 100% waterproof. Water simply cannot pass through a good healthy layer of properly applied concrete, block, wood etc. Epoxy also has an incredible bond to concrete, cement, wood and many other construction materials. The bond strength of epoxy to concrete and cement is greater than the tensile strength of the concrete. That means on properly prepared concrete, epoxy cannot be removed without pulling concrete with it. The same is true about wood.

Considerations in Waterproofing with Epoxy

All this gives you the perfect combination to make a block wall watertight. There are limitations however:

  1. In an ideal world the epoxy should be applied on the positive pressure side of the wall, the outside. This way the pressure of the water is pushing it into the wall. That helps to mitigate the likelihood that you get so much pressure on the concrete block that you fracture the block. Typically by the time you know you have a leak you are already backfilled and landscaped so 95% of the time it is not practical to do on the outside of the wall. So you do it on the inside instead.

    Water exerts a pressure of less than ½ psi per foot of water depth and most basement walls are only 8 foot high, so you would typically only see 4 psi. So it is unlikely that you have a pressure greater than the tensile strength of the block. So doing it on the inside is typically the only economical alternative.

  2. The Product #1W Epoxy is much more flexible than the concrete block and mortar, but if the mortar or concrete gets any significant cracks in it, it will crack through the coating. On the other hand, the system is very easy to patch if it does crack. We also make a wall grade version of our crack isolation membrane Epoxy.com Product #32 – www.epoxy.com/32.htm – which can reduce the potential for small cracks (which are the most common).
  3. A clean substrate is required for maximum effectiveness – www.epoxy.com/surfaceprep.aspx. For technical support contact me at norm@epoxy.com or 352-533-2167

Installation of Epoxy Waterproofing on Block Walls

Once the wall is clean, you need to point-up (fill) any cracks, bad mortar joints, and larger holes that are in the block. Some people use conventional mortar and wait 28 days for it to cure as per the American Concrete Institute. This is a very inexpensive way to do it, but can be affective if done properly. A more effective way to insure the right results is the use of Product #2005 Epoxy Gel Adhesive – www.epoxy.com/2005.aspx. That insures that you have a tight bond over the cracked areas and have already produced a tight waterproof seal in that area. Also the #2005 Gel Epoxy is semi flexible and allows more movement before cracking that conventional grout. The #2005 allows your coating to be installed the day after the #2005 is applied.

Once the cracks and holes are repaired, much of your work is done. You simply apply 1 coat of Epoxy.com Product #899 – www.epoxy.com/899.aspx – Epoxy Primer and allow to dry overnight.

After the primer has cured overnight you can apply the optional crack isolation membrane Product #32W – Wall Grade, or proceed to the coating below. If you do apply the crack isolation membrane 2 coats of the membrane are best. One advantage of the two coats of membrane is that typically you can reduce the number of coats of top coating that is required to seal the block. As you put on the membrane be sure to check to see that the holes in the block are being filled as you go.

Depending on the porosity of your concrete and if you used the crack isolation membrane above you will want to apply 2-4 coats of 1W epoxy wall coating. As you put on each coat check to see that the holes in the block wall are being filled.

Summary of Waterproofing Basement Walls with Epoxy

In conclusion: Leaking basements are a major problem to many structures in the spring. The easiest time to repair them is during the winter when there is little or no leakage. Epoxy.com epoxy coating systems can affectively and economically solve most basement leaking problems. The final product is a hard attractive ceramic like finish that does not require additional painting or other finishes over it.

Next Issue: Waterproofing Poured Wall foundations with Epoxy.

Additional Information on Epoxy Coatings

Product #1W (Wall Grade)  Epoxy Wall Coating – a general purpose epoxy wall coating

Product #2W (Wall Grade) Cemical Resistant Epoxy Wall Coating 

Product #32 (Wall Grade) Flexible Epoxy Membrane

Where to Start when installing epoxy.


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