I had a client call me the other day. Townhome style house in the northwest side of Chicago. Originally built in 2006. Client stated that house was never finished, structure, roof, interior framing, electric, plumbing done, but no drywall or insulation. I did a permit search and there are no records of permits at that address.
And the house was constructed using 8″ textured single wythe CMU, also known as Split Faced Block. This type of construction has been an ongoing problem in this area since the mid 90s.
As it turns out, the house was finished and occupied, but it suffered from such water infiltration problems, along with the proverbial dreaded mold problems, that the owners fled and the house was gutted of all the drywall, insulation and anything else they could think of but they left the electrical and plumbing.
I hope this article will help others to understand this type of construction, what the problems inherent in single wythe masonry construction and the proper construction methods that are needed so the house does not become a mold encrusted mess. It will also demonstrate that sealing the exterior block, either with a penetrating sealer or a ‘plugger’ type elastomeric paint makes little difference when the masonry flashing is not done properly.
First off, the house did have the exterior painted with a water proofing type paint. Such paints, or ‘sealing’ as it has become known as, are usually elastomeric paints. You see them used all the time on Public Storage buildings. The theory is that sealing the exterior from water penetration will stop the water infiltration. As is typical with this ‘solution’, the paint was applied all over the exterior, including sealing up the weep wicks and lintel drainage spaces. Most building sealed like this, in my experience, wind up having the paint bubbling off as the moisture that managed to get in anyway tries to get out. It is actually locked in by the paint. Sealing is NOT a long term permanent solution to the problem. It also gives a false sense of security, at least until the levy finally breaks.
The front elevation of these buildings are usually not constructed of CMU, but instead are
4″ concrete block structure covered with a brick, stone or some other style of facade. In this case, the facade was 4″ Renaissance Stone, a cast, polished concrete product that has been recently used as a substitute for the traditional Chicago style of limestone. In this house, they attached a metal framed front stairway but only anchored it in the stone veneer. This caused the stone to separate from the house and cause the veneer to crack and fall off on the side of the house.
The rear balcony was not much better. It was metal framed. but only
supported by the ledger board being bolted through the CMU at the rear. The ledger was separating from the block and the interior bolt had a vary small washer, almost completely sucked into the block on the inside. Keep in mind that this house had no building permits that could be found, was originally built and sold in 2006 and had been lived in for at least a couple of years.
The interior displayed all the typical split faced block water intrusion problems. The engineered wooden trusses, top loaded, were inserted in pockets in the block and this support pocket was grouted shut. This is actually a requirement in Chicago building codes. Especially in a single wythe masonry wall, this means that any moisture in the masonry will wick into the truss, eventually
rotting out the ends. Almost all of the metal truss gussets were rusted and there were water drip stains along all the walls.
All the electrical conduit and boxes displayed rusting. The copper water supply piping and PVC drain piping were still in place and appeared to be in good condition.
Where the trusses are supported by the masonry wall, there is supposed to be step flashing in the wall assembly, to block moisture from the truss ends and capture any moisture draining it out to the weep wicks. But, as is very typical, the flashing had no back damming. The flashing membrane was left to droop down on the interior of the wall. This allows water to also drain INTO the house, right above the hardwood flooring. So, if the client complains about buckling of the hardwood floors along the exterior walls, this is the cause.
The same errors were seen above the window and door openings. No back damming drooping flashing and no end damming. This has lead to EVERY window and door lintel in the entire
house to be extensively rusted and delaminated. All of them must be replaced.
The real cause of the water intrusion is NOT through the exterior walls. I know that people who have purchased
these type of properties want a quick and easy solution. Humans are like that, always looking for an easy way out. That is why ‘sealing’ the block has been so popular. But the water does NOT enter through the sides, at least not to any significant amount.
The water enters single wythe CMU block walls not through the side, but through the top. I used to be a big proponent of sealing the block exterior, but over the years and many evaluations of these type of buildings have changed my mind. The water enters through the
top of the wall, through parapet wall coping that has not been flashed.
This was clearly evident in this house. The parapet wall was covered with a stone coping with no flashing beneath. There was evidence of water intrusion in the parapet wall below, with many areas of cracking, both at the mortar joints and through the block. I noticed this fact when I discovered that split block buildings that had pitched roofs (i.e., no parapet walls) never had any water intrusion problems.
So, the real issue is one of poor (or non-existent) flashing, not the block itself. Granted, split block does absorb water more than other building materials and one should never build with single wythe style in Chicago, but there is hope for these type of buildings if they are either built properly, to begin with, or repaired by a licensed and qualified contractor who understands the cause of the problem and does not just want to do a quick ‘sealing the block’ job.
Our company also offers Split Block Certification. We inspect the property, recommend repairs and evaluate the repairs afterwards. If done properly, we issue a certification of the building (single and multiple family). We have evaluated more than 200 buildings like this and have never had a single complaint after the repairs.