Moisture Problems in the By Greg Tuttle, graduate leakage. This publication as student, Department of discusses these problems and a liquid on the nearest surface that Agricultural Engineering, and points out means to help you is Susan Mireley, associate identify whether the problems exist in cooler than the air. Three professor and Extension your home, determine their cause(s) conditions housing specialist, Department and implement effective solutions as in the home increase the chances of Human Environment and quickly as possible. that condensation will occur. The Design, first Michigan State University. CONDENSATION of these is a relatively recent phenomenon, a side effect of the efforts many homeowners have In recent years, Michigan Condensation can be a problem in taken to increase the energy Cooperative Extension Service both winter and summer. In winter, it efficiency of their . Many staff members have reported an often appears on first in the have added insulation to cut heat increase in the number of form of fog or ice on panes. loss and heat gain, while others questions coming into county In the summertime, water dripping have caulked and weatherstripped offices about moisture and water- from tanks and cold water pipes around windows and to related problems in the home. and condensation on masonry or reduce the infiltration of cold air The complaints occur in both stone surfaces in are the into their homes. The same winter and summer, and they take major causes of frustration. a variety of forms. practices that trap heat in the Some homeowners complain home also trap high levels of about water and ice formation on Causes of moisture. interior windows in winter. Others Condensation complain about peeling exterior A second common condition paint and the growth of mildew All air contains water in the gaseous contributing to moisture problems and mold inside the home. Still or vapor form. The temperature of in Michigan homes is the existence other homeowners report the air determines how much water of cool surfaces with which interior frustration over water collecting in vapor it can hold. As air gets moisture vapor naturally comes in basements or crawl spaces. warmer, its capacity for holding water contact. This problem often occurs Resulting odors and concerns vapor increases. On the other hand, in the homes of people who have about structural damage that as air cools, its capacity for holding not insulated or weatherized. In could occur and the hard work water vapor decreases. When air less energy efficient homes, and expense needed to clean and cools and its vapor-holding capacity certain locations are prime repair any damage are major decreases and the amount of vapor candidates for condensation concerns. in the air stays the same, the air may problems because they commonly All of these problems involve one eventually reach or exceed its have cool surfaces. These include or more of the three most saturation level. At this saturation poorly weatherized and insulated common types of moisture point, the excess vapor from the windows (in winter), poorly problems in Michigan homes: air insulated exterior and condensation, seepage and will begin condensing and collect (winter), masonry or concrete surfaces (summer), toilet tanks (summer) and cold water pipes (summer). second alternative available to covering the ground, crawl spaces A third condition contributing to lower should be provided with adequate household condensation problems summer time humidity levels is to natural ventilation to facilitate air is excessively high humidity levels purchase and operate a movement throughout the space. in the air within the home. Humidity dehumidifier. If a vapor retarder is present in levels are expressed as percentages If humidity levels remain high in the , 1 square foot of and can be measured somewhat winter, you may need to run it free vent area is required for accurately with inexpensive gauges then, every 1,500 square feet of crawl purchased at local hardware stores. too. A dehumidifier uses space ground area. Without a The normal indoor humidity range in mechanical vapor retarder present, 1 winter is 15 to 50 percent. In the means to provide a cool surface square foot of free vent area is summer, the humidity range may be where condensation can occur. A required for every 150 square higher because of the higher outdoor container located below the feet of crawl space ground area. humidity levels we sometimes condensation coils catches and Most crawl space vents include experience then. collects the condensed water for louvers and/or screens to prevent eventual disposal down a drain. the entry of insects and small High Humidity Level Problems Though both air conditioners and animals. These coverings slow Because high household humidity dehumidifiers are effective air circulation and cut down on levels can cause problems in both solutions to excessive moisture the vent's effectiveness. Thus, energy-efficient and less energy- problems, they are relatively you will need to double the efficient homes, the first step to be expensive to buy and costly to amount of ventilation needed taken in attempting to control operate. Expect increases in your in most cases to compensate condensation problems is simply electricity bills during the months for this reduction. For example, to reduce the level of humidity in you use them. a 1,500 square foot crawl space the inside air. would require 1 square foot of During the winter, the humidity level on Crawl Spaces ! free you will want to attempt to achieve in In homes built on crawl spaces, vent area if a vapor retarder was your home will depend on the outside evaporation of moisture from the present on the ground. If the vents temperature. As outside temperatures earth is a major source of used had screens or louvers, 2 drop, you need to lower inside relative household humidity The high square feet of vent area would be humidity levels to minimize levels of humidity in crawl spaces needed to vent the crawl space condensation (see Table 1). Monitor can be a problem in both summer adequately. Locate vents near the interior surfaces of double pane and winter. Foul odors in the corners and across from one windows during winter. If running home or crawl space, mold and another to facilitate air movement water (condensation) is apparent on mildew growth in the interior of through the crawl space. them, the interior relative humidity the home (especially in ) level is too high and should be and growth of fungi in the crawl Attic Ventilation ! lowered. Levels to achieve in summer space itself are signs of the Adequate natural ventilation is are somewhat more arbitrary-they problem. Covering the crawl important in the attics of homes as depend mainly on how uncomfortable space ground with a vapor well. If a vapor retarder is not you are in high humidity conditions. retarder (polyethylene or heavy present in the to slow plastic sheets available at migration of moisture from the Summer Problems ! lumberyards) is crucial in home's interior into the attic, attics During the summer, one of the major preventing moisture problems in require 1 square foot of free vent functions of an air conditioner, in crawl space homes (see Fig. 1). area for each 150 square feet of addition to cooling warm interior air, is attic area. removing humidity from the In addition to a vapor retarder home. A An exception occurs when the problems for attic vents are located in a homeowners: humidifiers, new construction or, remodeling, and high/low configuration (i.e., half of malfunctioning combustion appliances. the vent area in the eave/soffit area and the other half in the Humidifiers ridge area). In that case, 1 square foot for each 300 square feet is Many homeowners use humidifiers to add moisture to their homes in winter. adequate. If a vapor retarder is In the past, when homes were leaky and so less energy efficient, much of the present in the ceiling, attics moisture generated inside the home went out with the warm air escaping require 1 square foot of free vent around and through windows and doors. area for each 300 square feet of attic area. Overly dry air was common, and people experienced static electricity buildup on carpets and clothes, breathing difficulties due to, dry, nasal passages and A number of types of vents are somewhat destructive overdrying of . To combat this dryness, they available to provide attic commonly used humidifiers. Some were incorporated directly into forced air ventilation (see Fig. 2), As with heating systems, and moisture was circulated in the home along with heated crawl space vents, most include air. A second type of humidifier, the free-standing model, is portable and can louvers or screens to prevent the be. moved freely around the home to provide moisture where it is most entry of insects and rodents, and needed. Whether you have extensively weatherized your home or not, these coverings slow air experiencing condensation problems means you should not use a humidifier. circulation. Therefore, twice the amount of ventilation is needed in most cases to compensate for this Construction Moisture reduction. For example, a 1,500 square foot attic would normally Homeowners who move into a newly constructed home or complete require 10 square feet of vent remodeling projects often experience high moisture levels in the interior as area if a vapor retarder was not the materials and systems dry. If it is necessary to close the present in the ceiling assembly. If because of cold weather, the problem may seem excessively serious. Over the vents used had screens and time, the building materials will dry and a form of equilibrium will be louvers, 20 square feet of vent established. In the meantime airing the house when you can and using area would be necessary to vent exhaust fans will help to move the moist air to the outside. the attic adequately. With or without a vapor retarder, Malfunctioning Combustion- Appliances circulation of the air throughout the attic space would be more Oil- or gas-fired heating appliances that are not functioning properly or effective if the vent openings unvented heating units can cause a buildup of moisture, in a dwelling. If you were distributed equally between suspect any combustion appliance in your home is not functioning correctly, low areas (eave and soffit) and have a repair person inspect it. Heating systems in particular should be high areas (roof ridge). regularly inspected and adjusted by a heating contractor. Oil-fired need annual inspections. Gas fired systems, depending on their age, can be Mechanical Ventilation A final inspected less frequently, though three years is the maximum time a gas- method to reduce interior humidity fired unit should go without being serviced. If you use unvented space heat- levels is to control inhome ers in the home, follow the manufacturer's use and maintenance instructions sources of moisture vapor carefully. generation. Fig. 3 shows some of the significant sources of water vapor in the home. The , bath, laundry and utility are primary moisture generation locations. Consider installing exhaust fans or vents in both the kitchen and the if they are not present. The vents should be ducted directly to the exterior of the home rather than to an attic

Additional Moisture

Three additional sources of moisture periodically cause or some interior space. Clothes and caulking on both the inside with the added insulation to dryers should always be vented and outside (see Fig. 4). prevent the migration of vapor to the outside as well. Removing into these areas from the interior moisture and depositing it A number of bulletins available of the home. Note: specially outside is an effective way to at your county Cooperative formulated vapor retarder paints control condensation problems in Extension Service office provide are available on the market. both winter and summer months. information on caulking and They seem to be the least weatherstripping procedures. Ask expensive and the easiest way to Cool Surface for Extension bulletins E-1104, create a vapor retarder on the Weatherstripping your Doors and winter warm side of the ceiling or Condensation Windows (covers when insulation is added to weatherstripping, caulking, these areas. Problems adding storm windows); E-1573, In less energy-efficient homes, Caulking and Weatherstripping, Sealing Interior Cracks and cool surfaces are readily and E-954, Replacing Broken Holes available for water vapor to Window Glass. condense and collect on. When you add insulation, be Warming these surfaces by sure to repair, caulk or Exterior Peeling Paint and adding insulation or cutting down weatherstrip any holes or cracks on the amount of cold air that Ceiling/Wall Discoloration in ceilings, walls and and can get to them by caulking and Problems along baseboards These are weatherstripping will lessen Peeling exterior paint and prime areas for moisture condensation problems. discolored interior walls and migration to occur (see Fig. 5). ceilings (usually in the form of Moisture vapor moves with air, Window Surface Problems mold or mildew growth) are good and any cracks or holes that allow air to flow freely through Condensation on window indications that condensation is them are potential trouble spots. surfaces in cool or cold months occurring inside wall cavities and Recent findings indicate that the can be controlled by adding attics. During winter, cold outside sealing of these small, often layers of glass in the form of air collects in these areas and overlooked areas can be a major storm windows or using double- can cool attic, ceiling, wall factor in solving moisture or triple glazed window units, cavity and interior wall surfaces problems occurring in attics and installing a plastic film on the to the point where condensation wall cavities. For additional outside or inside of the window occurs. Adding insulation to information on frame (a less expensive way to these areas will warm these add storm window protection), surfaces and thus help prevent repairing broken glass, and condensation. Vapor retarders sealing any leaks in and around should be used in conjunction the window with weatherstripping weatherizing, consult Extension Michigan Homes; E-1103, Insulate Wall Repair and Fasteners. They bulletins E-813, Weatherproofing Your Unfinished Attic; and E-816, are all available at your county Cooperative Extension Service side of the insulation, will prevent Cooperative Extension Service office. moisture that migrates or seeps office. Keep in mind, too, that if through the concrete or block wall condensation is occurring in the Wall Condensation from eventually damaging the basement during humid summer Problems insulation. Others think this second weather, windows and doors to the Adding insulation to basement walls layer is a waste of money and basement should be closed to help has advantages similar to adding it maintain that insulation should not keep the humid air out. Open doors to wall cavities and the ceiling: it be added to basement walls until all and windows when outside humidity eliminates cold surfaces where water seepage and leakage is levels are low to introduce dry air condensation can occur, and it cuts corrected.) into the basement. energy costs. Basement walls are often insulated by adding furring Rigid insulation is relatively Toilet Tank and Water Pipe strips to the walls and installing impervious to water and moisture Surfaces rigid or batt insulation between the vapor damage. Therefore, it does Toilet tank surfaces are another furring strips. If you use batt not require the addition of a vapor common place for condensation to insulation, install a vapor retarder retarder over or behind it when it is occur, particularly during warm, such as polyethylene film on the added to basement walls. As with humid months. Warm toilet tank winter warm side of the batt batt insulation, drywall can and surfaces by either installing rigid insulation to prevent future should be used over rigid insulation waterproof insulation on the inside moisture migration into it. to provide a finished look and, in of the tank or adding a mixing valve accordance with building codes, to to the cold water supply line. This To achieve a finished effect, place provide a fire protective covering introduces hot water into the tank drywall over the vapor retarder. over the material that separates it water supply and can help warm the (Note: There is some question from a habitable living space. tank to a level that prevents about using a second layer of condensation. Install tubular or polyethylene when batt insulation is Procedures for adding insulation to wrap insulation around water pipes used on basement walls. Some basement walls are described in to prevent condensation there. believe this second layer, located Extension bulletin E-1 105, on the basement wall or winter cold Insulate Your Basement Walls, available at your local county Using natural ventilation and vapor retarder paint on ceilings and walls Use mechanical ventilation to will help control a significant remove moisture. Use exhaust fans amount of the moisture vapor that Weatherization - in and baths when migrated into these areas. It is Related Humidity moisture-generated activities occur especially important to repair or in these areas. These fans should seal all holes, cracks, or leaks that Problems be vented directly to the outside. In allow air to migrate through the In homes where moisture problems winter, some heated air will ceiling or walls. Finally, it may be become common after extensive obviously be lost through these fans wise to open the house periodically energy conservation efforts, the as they remove humidity from the on milder winter days to let in procedures described in previous home. Studies indicate, however, cooler, drier exterior air. This may sections will help solve the that the cost to make up for this loss be especially important in a newly problems. They are briefly noted is not excessive. constructed or remodeled home. here. Controlling the source of excess moisture is extremely important. Place vapor retarders over crawl space dirt. Limit use of humidifiers and keep fossil fuel-fired heating equipment in good condition. SEEPAGE AND LEAKAGE runoff close to the (see Seepage or leakage problems Fig. 7). Eavestrough discharges commonly occur in the basement or should terminate at least 3 feet crawl space in the early spring away from the basement/ foundation when snow and ice are melting and wall and gently slope away from the frost is beginning to leave the foundation at least 1 inch per foot of ground. They can also occur in the discharge run. spring, summer and fall during and after heavy rains. An adequate ground slope away from the basement/foundation wall Seepage in a basement is the slow is needed to ensure that rainwater (non-pressurized) movement of will be distributed away from the groundwater through the basement foundation. Generally, a slope of 6 walls. It may appear as a damp inches in a 10-foot run of ground is spot in an isolated area or in many adequate. All pockets or openings spots. Leakage, on the other hand, between the soil and the foundation is the fast (pressurized) movement should be filled with clean material of groundwater through the wall. In that has good drainage the case of leakage, the entry characteristics, such as pea gravel routes for the water are cracks or and sandy soil. joints in the wall; with seepage, the water migrates through pores in the Window well covers should be wall material. installed so that rain-water will not collect in the wells. Locate lawn Two conditions must exist for sprinklers so they don't sprinkle the seepage or leakage to occur. First, walls. the soil near the basement or foundation walls must be wet or A sump pump can be attached to saturated. Second, the basement or the footing drain tile (a building foundation wall must have a weak contractor will be needed for this drain. A professional may have to spot where water infiltration can unless you are an experienced do-it- be hired to help with these occur. yourselfer) to drain excess methods. groundwater away from the tile An additional solution for serious system and discharge it into a sump basement moisture seepage/ Soil Saturation well set in the basement . In leakage problems is installing a turn, the sump can then pump the footing drain tile system around the Wet or saturated soil near waste water into the storm sewer exterior walls. While this is being basement walls can have several system or to a ground area adjacent done, the exterior side of the causes (see Fig. 6): improper to the house. Choose a spot where foundation walls should be disposal of roof water runoff, poor the water will not damage the waterproofed (see Fig. 9 for a surface drainage away from the foundation or any adjoining method commonly used). This house, separation between the property. solution involves excavating the basement or foundation wall and Contact your local township or city soil around the exterior walls, the soil surrounding it (this crack building officials for specific installing a footing drain tile system, acts like a funnel), window wells guidelines on where to dispose of waterproofing the wall, backfilling collecting rain water, lawn sump pump discharge. with clean and porous material, and sprinklers located too close to the sloping the backfill away from the house, an inadequate belowground walls. Contact your footing drain system or a high water Wall Repair and table. Conditioning

Once the soil is wet or saturated, If the seepage or leakage is cracks, weak joints or pores in the occurring through a small, visible masonry provide a route through crack, use a wire brush to clean the the basement or foundation wall. crack and fill it with mortar cement Alleviate wet or saturated soil near or hydraulic cement. For larger the basement walls by minimizing cracks, chisel out a dovetail groove or eliminating the moisture at its (see Fig. 8) and clean and fill the source. The installation, repair and groove with either mortar or maintenance of the gutter, hydraulic cement. If leakage is downspouts and eavestrough heavy or under pressure, you may discharge system are necessary to need to install weep pipes to direct minimize the ponding of roof water the leakage to a sump pump or local township or city building associations, or lumberyards? Are Finding solutions to moisture official to secure information about they licensed with the state of problems, be they condensation or discharge of footing drain tile water. Michigan? The State Licensing and water problems, is often a difficult, The addition of a footing drain tile, Regulation Department can tell you. time-consuming and expensive weep pipes and the procedures Contact it at (517) 335-1669 or 337- undertaking. The first step in any involved in attaching an existing 0678. Ask for the names of at least situation is to identify the source of footing drain tile to a sump pump three references who have had the problem. This may not be easy are expensive and time consuming. work similar to yours done by the because two and often more things Consult an experienced building individuals or their companies. Ask may be working together to create contractor, engineer or architect these people if they were satisfied the problem. before attempting these solutions. that their problems were correctly Before you hire anyone to do such identified and solved. Finally, a job, look for background determine if working arrangements information about these people. and business dealings between the How long have they been in references and the contractor were business in or near your comfortably and professionally community? What type of handled. reputation do they have with local banks, savings and loans CONCLUSION Once you know the source, rethink the basics about condensation and/or water problems discussed in this bulletin. What are the no-cost or low-cost solutions you can try first? Can the solution(s) attempted help you in other ways in addition to solving the moisture problem? The addition of storm windows, for example, can cut heating costs as well as help prevent fogging or icing of windows. In such a case, the cost of the solution may be well justified. In some cases, you may find you have to rely on outside help, such as contractors, engineers or architects. Do look into the backgrounds of these people to ensure that you are getting the best help available and that the solutions they offer will indeed solve the problems. SOURCES

Angell, William. Correcting Basement Moisture Problems, Special Report 2. St. Paul, Minn.: Agricultural Extension Service, University of Minnesota, 1981.

Merrill, John. Moisture Problems in the Home, B3371. Madison, Wis.: Cooperative Extension Service, University of Wisconsin, 1986.

National Center for Appropriate Technology Moisture and Home Energy Conservation: How to Detect, Solve and Avoid Related Problems. GPO 061-000-00615-0. Washington, D.C.: Government Printing Office, 1983.

Small Homes Council-Building Research Council. Moisture Condensation, F6.2. Champaign, Ill.: University of Illinois, 1975.