Sealing Split Face Block Does Not Solve The Water Issue, But There Is A Better & Permanent Solution!

Written by Greg Nagel, Ask Nagel Realty but with most of the Content Provided By Will Decker.

I believe Will Decker of, and Bob Kelly of have come up with a combination of the best solutions for arresting the Split Face Block building moisture issues facing West Town and many other Chicago neighborhoods.  In summary, their solution is a Certified Split Face Inspection Process, and some relatively easy one-time repairs focused on sealing the parapet capstones and ventilating the block.

As many of you already know, I’m a real estate broker who does not like split face block buildings, and I have been avidly speaking out against them for a decade.  I have steered many of my buyer clients away from them, despite the fact that it makes my job of finding my buyers a home in their budget far more difficult.  However, it becomes even more challenging when I’m hired by a seller who has a split face block building.  How do I help them?!

One of the challenges with split face water issues is that there are lot of experts out there with differing opinions.  The word on the streets is that you will always have to seal the block, which can cost typically $6K-20K for a typical 3 flat condo building.  There are lots of conversations on the type of sealer, clear vs the heavy paint-looking sealer, or an elastomeric sealer.  There is also lots of conversation about the best method of application, sprayed on versus painted on, or even pressed into the grooves in both directions.   I’ve even heard people talking about the weep holes as the main source for the water issue.  Please note that a 6K job is typically a short term clear sealant that is hand sprayed likely to last only 3 to five years.

In Will’s opinion and to many people’s surprise, sealing the block will have very little impact!  Will has found that only 8-11 percent of the time the water is coming in from the block on the sides!  The majority of the intruding water enters the wall through all three exposures of the parapet on a flat roof.  The capstones, AKA coping stones, that cover the parapet are typically made out of the Limestone or Renaissance stone which are both very attractive, but also very porous.

Will explains that the reason why split face block buildings with pitched roofs don’t typically have these water issues is that they don’t have parapets with porous capstones on them.

The analogy Will shared with me in comparing the benefits of sealing vs addressing the capstones was as follows:

What will keep you drier?

1) An umbrella – Flashing under the capstones


2) A rain coat with no umbrella – Sealing the block?

Obviously the umbrella is better as you will only get a little wet on the sides, which can naturally air dry.

And to stick with the metaphor – proper ventilation will allow the stone to naturally dry out from the side moisture.

There are some relatively minor repairs that can be made that can permanently solve the split face water issues:

  • Installation of a non-porous membrane of rubber or metal (called flashing) over the entire width of wall and under the capstone.  This serves as a barrier to water intrusion through the porous capstone.
  • If the parapet wall capstone is flashed, and also ventilated, this will allow the air within the block cells to “breath” and promote evaporation and convection of the air cavity.  If weep vents are added at the through-wall joist pocket flashing, this air flow is even better and allows more air drying of the block cells.

 The ideal product that does both of these is sold by Wick Right Inc: which is a ventilated flashing product that stops water from penetrating, and allows the stone to breathe out the top.  It’s about $80 a lineal foot installed, which should be about 15K for the typical 3 flat, which is still cheaper than most sealing companies. Furthermore, this is a permanent solution unlike sealing which needs to be redone every depending on who you ask every 3-7 years.


In addition Will has created an inspection process called, “Split Faced Certified”, which is a complete regimen where a subject building is inspected by a specially certified inspector.  If there are any outstanding issues, these are specified and can be repaired by certified contractors with special expertise dealing with split block water intrusion problems.  Well then gives out 3-4 referrals of qualified companies for the homeowner to select.  When the work is done he will go out and re-inspect at no additional charge, and assuming work is complete and done adequately, he will then issue a certification letter.

Will who is completely independent of Wick Right, believes that this patented Vapor Release System is the best product available.  Bob Kelly at has a great educational website including one video showing water pouring out of a split face building – very shocking!  He also has another video that explains why split face block buildings fail.

I will be coaching my selling clients to get this Certified Split Face Inspection which costs $650, and advising them to make the needed repairs.  At a minimum, they should put metal flashing over their capstone for a less expensive solution.  However, they should preferably put a ventilated flashing product under the capstone which is more money but better as it allows the wall to breathe, and release moisture vapor and help eliminate mold growth within the building.

I feel that this best info out there, and Will is the most reputable expert out there.

Will has three great articles on this topic that address different aspects of this:n

Will Decker Article Explaining the Problem & Repairs That Can Be Made.

Will Decker Article Explaining the Certified Split Face Block Inspection program


Will Decker Article that goes into more technical detail.

I hope this info helps some folks that are struggling with these issues.