Robert Lamoureux | Intrusion requires ‘positive waterproofing’

Robert Lamoureux
Robert Lamoureux

Question No. 1

Hi Robert,

I hope you are well and staying safe. We spoke two years ago when I had damage to my patio slab due to multiple leaks from the common area, which the HOA repaired. My slab was covered with epoxy paint to cover damages. I am now having a water intrusion issue on my storage room wall, which began during the rainy season last year. The wall sits below (underground) the patio. There is an email string below between the attorney and me that will help describe the issue. Is this serious? Thanks for looking. 

— Stacy

Answer No. 1


I read through communications you shared, between your attorney and yourself. The details you give, along with the photos, show that what your attorney said is exactly right, this is a water intrusion issue and the proper fix is to waterproof this CMU wall from the exterior, what we call “positive waterproofing.” 

Your photos prove my point and show that negative waterproofing —  which is to seal the wall on the interior — only buys a bit of time preventing the water from manifesting on the inside. 

What is still happening during that time, though, is that the water is still getting into the CMU blocks and causing the deterioration of both it and the rebar that is inside. Eventually, enough damage is done and, as the block deteriorates and spalls (breaks apart), even the sealant cannot hold it back. As it spalls, it takes up more space and pushes through the sealant, which is then the path that the water can take to escape. 

What you don’t see is the interior of the block and the damage that is happening there. The moisture is inside, against the rebar, which is the metal rod giving the block its additional strength. This rusts and, as it does so, expands, pushing the block apart. 

The integrity of the wall is now compromised and, in small amounts, is not detrimental, but as it continues, the stability of the wall continues to deteriorate. Eventually, this will become a structural issue because the wall is then not strong enough to hold up what is above it and in most of these cases, that is the building. 

There is no doubt that the positive waterproofing (waterproofing from the exterior) is more expensive than the negative (from the interior), as digging down below grade is necessary. However, it ultimately is far less expensive than the ultimate repairs that would be necessary, or the liability from ignoring the issue. 

In my experience, I’ve seen insurance companies not pay out on claims where there were known issues and proper maintenance or repairs were not done. 

I would share all of this information with your HOA board, documenting everything. You as an owner have a due responsibility to notify them of findings, and this is a big one. 

I highly recommend that this be repaired properly so it does not continue to deteriorate and decrease the integrity of the structure. 

Best of luck, feel free to call me if needed. 

— Robert

Robert Lamoureux has more than 40 years of experience as a general contractor, with separate licenses in electrical and plumbing contracting. He owns IMS Construction Inc. in Valencia. His opinions are his own, not necessarily those of The Signal. Opinions expressed in this column are not meant to replace the recommendations of a qualified contractor after that contractor has made a thorough visual inspection. Email questions to Robert at [email protected].

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