The Chicago Spring Market has begun and as always, we are constantly looking for new clients to both buy and sell their homes. We pride ourselves on giving the upmost level of service to our clients we represent. And we encourage you to reach out to us to get to know us better and let us know how we can assist you or someone you know.
We are out daily with buyers looking at various interior finishes and trends in decor, but often over-looked is the exterior construction and what red flags need to be addressed with a prospective property. Transparency is key with us on both the listing and buy side of a transaction. We love to educate our buyers on the construction of units with the materials used. One of the most popular construction on units built in the late 90’s and early 2000’s is Split-Faced Block.
What is Split-Faced Block and Why Was It Used?
Split face as seen in this Lincoln Park condo. Typically used on 3/6 flats on the rear and sides of construction
By William Decker, CMI
Since the mid-1990s, especially during the building boom of the early to mid-2000, there were many new condominium buildings constructed in the Chicago area. Many of these condominium buildings utilized a newer exterior masonry product that is commonly called split faced concrete block. This material looked like an 8″ thick common “cinder block”, but had a rough face, making it look like stone (Right). The material is manufactured using aggregate, Portland cement, and course sand. During manufacture, a complete 16″ block is “split” in two so as to form two 8″ thick blocks, each with a rough face along the split edge. The finished product resembles rock-faced masonry in Richardsonian Romanesque houses popular in the mid-1880s (below). But, as we shall see, prioritizing form over function can lead to long term problems when building houses.
Split-Faced Blocks as commonly seen in the gangway of a Lincoln Park 3 flat
Split faced block was commonly used as the exterior wall cladding on the sides and rear of 3, 6 and 8 unit condominium buildings and some single-family houses with the front of the buildings, usually, being covered with brick or stone. “Was used” is the operative phrase because using this material in new construction residential buildings has, largely, been stopped in the Chicago area, in late 2009.
Split faced block was chosen by builders for a number of reasons, but the biggest one was cost.
Here are the cost factors:
– Split faced block material costs are low.
– Being larger than a brick, it is quicker to lay and faster to install.
– This block is strong enough to use as a structural wall (i.e. a wall that actually supports the building) and attractive enough to use as an exterior cladding wall at the same time (this is, technically, what is called a single wythe wall, a wall that is only one layer of masonry thick).
– The material could be installed by less expensive, sometimes newly immigrated, non-union masons.
Problems and Causes:
The problems seen with many split faced block buildings have been the result of water intrusion. The symptoms include water stains and bubbling paint on ceilings and walls, warping and buckling hardwood floors, water dripping from exterior wall outlets and light switch boxes, musty smells and mold formation. In extreme cases of long-term water intrusion, the roof and floor joist ends get wet and rot. This can lead to catastrophic structural collapse, where roofs and floors collapse! It is important to realize that these are not the problems, they are merely the symptoms of the real problem which is water intrusion into and through the block. Many times, homeowners will have the roof replaced or “fixed”. When water is coming through your ceiling or walls near the ceiling, people logically think that the roof is leaking. I have many clients who had their roofs completely replaced, but the water kept coming in. The best solution is always to solve the primary issue (the water intrusion) before addressing the secondary symptoms.
PLEASE NOTE: Many fly-by-night predators (and even some reputable masonry companies), seeking a quick fix and a quick buck, are going around promoting “sealing” the exterior of the block as the “easy fix”. While using waterproof block or applying an exterior sealer may help in some cases, the block not being sealed is NOT the primary problem with these buildings. It is only one factor and a minor factor at that. In my research, I have found that only 8 – 11% of the water entering the building is coming in through the block, laterally. There are many split block buildings that have never been sealed but have also never had water intrusion problems. Each building is different in its construction and each building has to be evaluated based upon its individual construction details. Quick fixes offered by the proverbial “two guys in white panel van” cost you money and time but do not fix the problem.
Why does the water come in?
To fully understand why split faced block houses and buildings have water problems, it is first necessary to understand how these buildings were built. The first thing to understand is that all masonry is porous and absorbs water. Brick, stone, cinder block and split faced block will all absorb water. So why aren’t all the old brick and stone houses having water problems? The reason is that they were built with multiple wythe walls. Multiple wythe (width) walls are actually two (and sometimes three or four) walls in one. The inner one or two widths are structural and support the building’s weight, while the outer wall (sometimes called a veneer wall) does not. Between the inner and outer walls is an air gap, usually about 1″ wide. Water will travel in pretty much any direction, based on gravity, pressure differences, humidity, capillary action and heat gradients, but the one thing that water will not cross is an air gap. This is the biggest issue with split faced block buildings. They were, almost always, built without an air gap as a single wythe wall.
Even when built in the single wythe configuration, split faced block buildings can avoid water intrusion problems if they are properly designed and built. Looking at the diagram to the left, we see how a split faced block wall should be built, based upon building science best practices and industry standard specifications. But these details are rarely used.
Coping flashing – The top of the exterior walls (also called the parapet) must be properly sealed. The top of the wall is usually covered with a piece of stone. This stone is supposed to keep rain water from entering the top of the wall and seeping through the masonry. Think of an umbrella. Many masons are not aware that this stone, itself, is porous and, given time, moisture will still get through. Older buildings were constructed using limestone that was 3 – 4″ thick and would dry out faster than the rain made it wet. The newer product (which is much less expensive) is a small aggregate concrete block that is polished to resemble limestone (Renaissance stone) and is usually 1 3/4 – 2″ thick. It is also very porous to water.
Best practices call for the installation of a non-porous membrane of rubber or metal (called flashing) over the entire width of wall and under the coping stone. This serves as a barrier to water intrusion. This construction detail is crucial because the majority (70 – 80%) of the intruding water enters the wall through the coping stone.
Parapet wall ventilation – While the top of the parapet wall should be covered and sealed to keep water from entering the top of the wall, the wall itself should also be ventilated. This is a classic construction technique that has been used for hundreds of years but seems to be lost to most modern Architects and Builders.
The Air Cells Within The Split Faced Blocks
The blocks themselves have air cells inside (left). If these internal cells are allowed to ventilate to the outside, to “breath”, moisture that is in the wall will be able to evaporate and be less inclined to pass through to the interior. This is was done in the older brick buildings in Chicago, where the parapet wall was “capped” with clay coping tiles and many of these buildings are over 80 years old and still in good condition. The inside and outside edges of these tiles provided an air space that allowed the interior of the brick walls to breath.
Mortar and block cracks – Another concern is cracking of the mortar. Intuitively, we think that big cracks in the mortar between the block will allow more water to enter the wall. In fact, the opposite is true. Big cracks do allow water to enter, but they also allow this same water to drain out. Small, hairline cracks are much more of a problem. They do not just “allow” water to enter the crack that actually sucks it in through a process called a capillary action. Because the crack is so narrow, the surface tension of the water draws rain into the crack where it is soon absorbed by the blocks natural porosity. Another problem with the mortar is caused by the employment of masons who do not understand the local conditions. Many newly immigrated masons have a long tradition, “from the old country” to add extra sand to the already pre-mixed mortar. They believe that this will make the mortar stronger when it also makes the mortar more water absorbent. Both these factors lead to water being absorbed into the block.
Flashing – When building a house, all areas that can possibly allow water to enter the building should be, so to speak, waterproofed. The problem is that almost impossible because most building materials (wood, stone, masonry, and siding) are porous. The exterior of a building is not “waterproof” but merely water resistant. It allows water to “shed” off the exterior surface. These susceptible areas must be “flashed”. Flashing involves installing a water impermeable barrier (vinyl, rubber or metal) between the outside and the inside of the house, and between building materials of different water absorptive levels (i.e., between wood and masonry). Flashing materials do not allow water (or water vapor) to pass through them and act to drainage plane to further shed any moisture absorbed in the wall down and out. This is why some better-built properties have the flashing, along with small pieces or rope (weep wicks, below) sticking out of the side walls at the level of the floor joists.
Ropes in the blocks creating “Weep Wicks”
BTW: Home Inspection Rule # 101: “Caulking is NOT flashing!” Caulk will crack, come loose and deteriorate. Any opening that is caulked (window and door frames, roof penetrations, bathtub/tile corners) must also have flashing of some sort behind the caulk. Caulk alone will not stop water and, in most cases, is more cosmetic than functional. Many times, in an effort to “fix” water intrusion problems, inexperienced workers will caulk an opening that should be left open to allow for water drainage. This is commonly seen above windows and doors where the drainage space between the steel lintel and the block/brick is caulked or mortared shut. Rather than stop water from entering the wall, it blocks the designed drainage opening and causes water to back up and drain down from the top if the windows and doors on the inside.
Joist flashing – The floors and roof of these buildings are supported by floor and roof joists. Commonly, these joists are engineered wooden trusses, specially designed and manufactured assemblies that are much stronger than a normal solid piece of lumber. They are usually constructed of lengths of 2 x 4 lumber secured with metal plates called gussets. These truss joists are inserted into pockets in the block masonry walls. There should also be a flashing membrane installed between the block and the wooden trusses to keep water away from the wood. The truss should also be installed with supporting shims and there should be an air gap between the truss’s wood and the masonry. The membrane and the air gap both provide protection against water wicking into the truss. It is never a good idea for wood to get wet or be in contact with masonry. Problems occur when the builders, a) do not install the flashing properly and/or, b) grout the truss end pocket instead of shimming. In both cases, moisture from the masonry wicks into the wooden truss ends, rotting the wood and rusting the securing gussets. As we shall see, later, this can lead to a very serious problem.
Exterior wall flashing – The other reason for the joist flashing is to catch any moisture that is draining down, within the wall, and direct it outward, away from the building. This flashing membrane should be upturned on the interior side of the wall (so as to catch and drain the water outward) and extend out of the exterior side of the wall, forming a drip edge. The drip edge should extend, at least, 5/8″ away from the wall. Current national construction standards call for the exterior drip edges to be made of stainless steel or copper, for durability.
Many times, the masons (or the insulation sub-contractors) do not properly turn up the interior end of the flashing and this allows water to drain into the building, warping hardwood floors and causing tiles to crack. Similarly, many builders fail to properly extend the exterior drip edge far enough outward from the exterior of the wall which allows the water (both already in the wall and water falling on the wall) to be sucked back into the masonry mortar. It is am an ironic circumstance that many builders do not install this flashing because the buyers will think it looks “ugly”. Functionality should always trump any cosmetics of a building and they should be designed to be properly appealing in the first place.
Exterior wall sealing – Contrary to common believe, sealing the block is NOT the final solution, but does help (BUT DOES NOT CURE) the problem. While it is better to have the block sealed, it is not necessary if the building was properly constructed. Sealing adds water impermeability to the block and acts to shed water off the surface. When the exterior wall of the block is not sealed and depending upon local weather conditions, rainwater and humidity in the air is drawn into the block. This moisture travels through the masonry into the insulation and drywall. It should be stressed that the majority (70 – 80%) of the water intrusion DOES NOT come, from the sides, through the walls but flows downwards from the unflashed parapet wall coping stones and stone window sills. That being said, the moisture intrusion through the walls must not be ignored.
A curious phenomenon that we have observed, many times, is what is known as “solar loading”. Imagine a large building with split faced block sides and the south and/or west sides exposed to the sun. It rains for a couple of days, not a hard driving rain but just a steady drizzle. There are no water intrusion problems while it is raining. Finally, the rain stops and the sun comes out. After 4 to 6 hours (around 1:00 PM or so) water starts staining the interior wall and dripping through electrical outlet and light switch covers on the south side. One wonders why the water didn’t come in during the rain, but does when the sun is shining.
What is happening is that the sun is heating the exterior block wall. Intuitively, one thinks that the sun will dry the water. In reality, the sun is only “drying” the moisture on the very surface of the block. The rest of the water that has already been absorbed is actually being driven further into the masonry because the heat of the sun is expanding its volume, increasing the vapor pressure and further pushing the water that was already in the masonry out into the insulation, drywall and out the wall. This condition is exacerbated by the use of mid-efficiency forced air furnaces in many of these condominium units which draws a significant volume of air out of the building. The negative interior air pressure works to actually suck the water in through the block.
It is interesting to note and contrary to common sense that masonry buildings, in fact, do most of their drying out during the winter, not the summer. In the winter, heat moves outward from the heated interior living space. As this heat moves, it pushes any moisture in the masonry ahead of it (heated water expands). When this water reaches the exterior surface of the masonry, the cold, dry air causes it to evaporate. This sometimes leaves a white, fluffy powder on the outside of the wall. This is called efflorescence and is the result of the outgoing water dissolving some of the lime in the wall mortar. The water dries on the outside of the wall and leaves the lime. Because of a couple of relatively warm (and wet) winters in our area, problems with water intrusion in masonry has been much more pronounced.
The old, commonly accepted best practices method of split faced block sealing used to be applying a “pigmented, silicone based, silane/siloxane, penetrating sealer”, but it has been found that such products only lasted 3 to 5 years (depending upon the manufacturer and the skill of application). Many times, the sealing contractor has not been properly trained in how to apply the sealer, and the condition of many “sealed” buildings attests to this fact. Silicone silane/siloxane sealers MUST be applied in a flood coat, completely covering the block and allowed to be soaked into the block. Repeated sealing is also expensive, properly sealing a 3 story condominium building is expensive ($17,000 – 21,000, professionally done). The current preferred sealing solution is a polyurethane or elastomeric based “plugger” type paint, installed by licensed, insured, trained and qualified masonry contractors. This product will completely seal both the block and any small cracks in the mortar joints rather than just retard absorption and can last for 10 – 15 years. But, this solution does not solve the larger problem and will NOT guarantee that the building will stay dry.
Antiquated Sealing/Repairing Techniques
Drying out the retained moisture – When a split faced block wall has been exposed to moisture for a long time, it tends to retain (or “sequester”) the water deep in the block. Think of a wide sponge. If you spray it with water it will absorb the water. When the sponge’s capacity to absorb the water is exceeded (in building science, this is called the “hygric buffer barrier”) water will start leaking out the other side. But, the water being leaked is NOT the same water that is being sprayed on the other side. There is always going to be some water, “in the pipeline”, so to speak. Split faced block can absorb its own weight in water, and this retained water has to be removed.
Once the exterior walls and parapet have been properly flashed and sealed, no more water will enter the wall. BUT, there is still a great deal of water that is already in the wall, and will not dry out because the exterior has been sealed against water getting in, and water getting out.
To fully solve the problem, the water that has already been absorbed in the masonry has to be removed. This can only be done by greatly lowering the humidity levels inside the house, which will draw the water out of the masonry through the insulation and drywall. Remember, in a typical three unit, duplex down, condominium building with split faced block on the sides and rear, there is approximately 2,500 GALLONS of water that is still in the block.
This process requires time (3 to 4 weeks, depending upon the conditions) and multiple, industrial capacity de-humidifiers running, full tilt and 24/7, under closed building protocols. This requires that the doors and windows in the house or building be kept closed (except for normal entering and exiting). Many times, we have seen home and condominium owners who believe that once the cause of the water intrusion has been solved, they can just re-drywall and / or re-paint and everything will be fine. They soon find the same water stains reappearing, sometimes in less than a week. Solve the cause of the problem, then remove all the residual moisture before tending to the cosmetic details. A car may have a really shiny and smooth paint job and cool chrome, but what really counts is what is under the hood.
Learn more about us on our social media platforms; and let us know if you have anyone looking to buy or sell – we are always happy to help!