Water intrusion consultation for wet buildings and mold problems.
By William Decker, CMI
The Chicago area housing market has a growing problem that has occurred over the past couple of years. Houses and condominium buildings have been experiencing a large amount of water intrusion. Sometimes this water is the result of a leaky roof, always the first suspect, but more commonly water is entering the building through the exterior masonry walls and stone trim. Typical symptoms include water leaks above windows, musty smells, mold stains around ceiling recessed light fixtures, water stains on ceilings and baseboards and excessive efflorescence on the building's exterior. The picture, at left, is a fine example. Notice the powdery white smears on the brick. This phenomenon is called efflorescence. It forms when water that has been absorbed by the brick and stone (both are porous) and wicks outward when drying. This is especially evident in the spring, after the winter's drying process is finished (masonry dries out during the dry, cold winter months). As the water travels outward, it dissolves some of the salts from the mortar. When the moisture reaches the outside surface and evaporates, it leaves these salts deposits behind. Efflorescence, in itself, is not a problem and can easily be removed (with a vinegar and water solution) but it is a sign of a larger underlying problem. The masonry walls are not properly constructed, sealed and flashed so excessive amounts of water are entering the building envelope. Water intrusion leads to deterioration of the masonry, rotting of the wooden windows frames and floor joists, stained drywall and promotes mold formation.
There has been a large increase in water intrusion in masonry buildings in the Chicagoland area. Many people see water leaks through their ceiling or out of recessed light fixtures and HVAC ducts and immediately think that they need a new roof. And many roofers are all to happy to oblige them (after all, a roofer's job is to sell you a new roof, not solve the water intrusion problem). This is where a professional home inspector can be of help. We are there to determine the source of the problem and how it should be fixed, not to sell you a new roof or an expensive tuck pointing job. We are house diagnosticians and building scientists, not tradesmen. We have the experience and tools (like thermal imaging, deep probing moisture meters, mold sampling equipment, etc) to find the problem's cause and recommend how to fix it in the best and least expensive way.
See a recent news story video on this problem, here.
Our company has become (much to our surprise) The Chicago area's experts on water intrusion problems, unfortunately, because these problems are becoming more common. Here are some of the causes we have found:
Improper installation of coping stones: Buildings with flat roofs are built with parapet walls (around the sides of the roof). The top of this parapet wall is equipped with a coping cap. Older buildings have coping tiles (rounded clay files) covering the parapet. Newer buildings use limestone or cast concrete coping stones. Whatever material is used, this coping is a cover for the top of the masonry wall and guards against rain and snow entering the top of the parapet. With clay coping tiles, the joints connecting the tile pieces will deteriorate, over time, and allow water to enter the wall. Non-professional repair attempts, using plastic roof cement, only aggravate the problem. These joints should be sealed with hydraulic cement and sealed with caulk. The newer buildings, with stone coping, are usually just not installed correctly. Proper installation calls for the stone to be beveled and sloped (so as to shed water), to be equipped with a drip edge (a small groove, cut under the edges of the stone, which will cause water to drip off and not be absorbed under the stone) and through-wall flashing under the stone (a rubber, plastic or metal membrane, as pictured above). If the copings are not properly installed and flashed, water will enter the top of the building's walls and wick through into the interior. We have found this to be the single greatest source of water intrusion on masonry condominium buildings.
Improperly installed or missing flashing above windows and doors: Exterior wall openings (for windows and doors) are built using a lintel. This is an angled piece of steel that rests on the sides of the openings and supports the brick or stone over the opening (below, left). The area behind the lintel will accumulate moisture and it will flow down to the lintel. The lintel must have flashing (usually, a plastic membrane) that runs between
the lintel and overlying brick. This membrane will direct the water out, between the brick and the lintel so that it will not drip down through the top of the window or door frame. Many times, the builder does not properly install this flashing. Another overlooked construction detail is the fact that the lintel / brick space should be left open. Many inexperienced masons will grout (mortar) or caulk this gap closed. If this gap is sealed shut, the accumulated water will flow outwards and run down the sides of the openings (right) Note the efflorescence on the sides of the door and window). Newer construction techniques also call for "weep wicks", small pieces of rope that hang out of the lintel space or at the base or sides of the walls. These weep wicks suck water out of the wall and wick it to the air, much like a paper towel will soak up water. Too often, these wicks are missing, improperly installed or not the recommended nylon or polypropylene, but just cotton clothesline. Cotton weep wicks will rot and deteriorate after a couple of years. Likewise, the ends of the flashing should be turned upwards, called dam flashing, so that the accumulated water drains outwards and not into the ends of the window opening.
Unsuitable materials and improper construction detail: There are always new building materials coming on the market. Usually, these materials are superior (and less expensive) than the old materials and allow for a better building at a lower cost. But not all these materials are suitable for all climates. The Chicago area has a strange micro-climate. We have cold winters and hot, humid summers. Significantly, the past two winters (2006 - 2007) were fairly warm and wet by Chicago standards. Masonry buildings absorb moisture and must be allowed to dry out. Contrary to what many people believe, most of this drying takes place during extended cold (and dry) periods during the winter. Because of these two wet winters, the masonry buildings in our area have not been allowed to properly dry out. A newer masonry product, called split faced concrete block (right) has been used extensively over the past 20 years. This is a rough faced, more decorative form of the old cinder block masonry unit. Split faced block is very porous and is not suitable for our wet climate. It must also be sealed with a penetrating sealer (and re-sealed every 3 - 5 years) or it will absorb a great deal of water. Many builders don't know this or were misinformed by their suppliers and told that the block had already been permanently sealed (not a true statement until very recently). Split faced block must also be installed only as a veneer in a double wythe wall (a two layer wall with the interior, structural wall actually supporting the structure and with a 1" air space between the two walls). Many builders have used split faced block in a single wythe wall or not properly constructing the wall with the required air gap and flashing between the walls. Many times, unprofessional masonry sub-contractors will not remove the excess mortar from between the two walls, which bridges the air gap and allows exterior wall moisture to leach through to the interior wall. Additionally, in condominium buildings, many condo associations are not informed that the block must be re-sealed. As a result, many of these buildings are suffering from "wet building syndrome", where moisture has been retained in the walls and has caused extensive damage and mold formation. Some buildings that we have inspected have been built so badly that they cannot be repaired and must be torn down. A newer sealing material is elasomeric "plugger" type paints which have a service life of 10 - 15 years, much longer than the penetrating sealers and for about the same price.
We have a great deal of experience evaluating these types of problems and can provide an un-biased inspection using the latest technology. Our inspection report will provide you with quantitative information on the condition of the building and give suggestions on how the water intrusion problem can be solved. We also will be able to guide you to a number of forensic contractors who can properly, and finally, fix the condition.