print this chapter download report

Healthy Housing
A Handbook for Portland Property Owners

A number of local efforts have recently shined a spotlight on the relationship between the built environment and the health of low-income Portlanders. Poorly designed housing; a lack of sidewalks and safe crossings; and limited access to recreation, schools, nature, places for social interaction, vital services, preventive medical care, and healthy food all contribute to health challenges that disparately affect low-income residents and communities of color.

Mold and Moisture Control

Most Moist

Properties with aluminum windows and baseboard heating are most prone to mold and moisture problems.

Mold spores are naturally present in the air, and under normal conditions, they don’t cause harm to people or buildings. But when mold spores come in contact with excess moisture, and begin to grow on walls and other surfaces of a building, they can cause serious respiratory health problems for occupants. They can also do costly structural damage to the building. The best path to preventing mold at your property is to control moisture infiltration, assure good air circulation and educate residents about how to do their part.

Mold and Moisture Control Benefits

Resident Health
and Wellbeing

Controlling mold and moisture protects residents from serious respiratory illnesses and other health problems. Molds can trigger asthma attacks and allergic reactions such as sneezing, runny nose, red eyes and skin rash. To a lesser extreme, mold may irritate the eyes, nose, throat, lungs and skin.

Controlling mold and moisture helps keep kids in school and adults at work. Allergies, asthma, chronic coughing and sneezing caused by mold exposure may impair residents’ ability to carry out necessary responsibilities.

Controlling mold and moisture prevents damage and destruction of residents’ personal property. Mold and mildew can ruin furniture and other belongings.


Property Performance
and Condition

Controlling mold and moisture protects building structures and finishes from damage. Mold and moisture can cause extensive damage to walls, carpets, drywall, ceilings and subfloors.

Controlling mold and moisture prevents costly remediation and repair bills. Some molds are very dangerous and require the help of expensive professional remediation services to be properly contained. Also, contaminated building materials might need to be replaced.

Controlling mold and moisture reduces unit turnover. Chronic mold and moisture problems may drive some residents to move out, which increases vacancy loss and operating costs.

Mold and Moisture Solutions

    Management and Maintenance

    Mold Mantra

    Moisture control is the key to mold control.
    Moisture control is the key to mold control.
    Moisture control is the key to mold control…

    Properly ventilate each apartment unit.

    • Make sure that bathrooms and kitchen stoves have operable ventilation fans that exhaust to the outside. Choose quiet fans (with low sone ratings); tenants are less inclined to use fans that are excessively noisy.
    • Consider installing humidistat controls that automatically turn on bathroom fans when moisture levels rise and shut them off when levels subside.
    • Make sure windows can open for ventilation, especially in kitchens, bathrooms and rooms with identified mold problems.

    Protect your building envelope from moisture infiltration. Your building envelope is your only line of defense against precipitation and wind-driven rain.

    This roof has no gutter, so the downspout is clearly not serving its purpose.

    • Clean your gutters annually. It’s best to do this in the fall, after trees shed their leaves. Take this opportunity to inspect your gutters for damage and make sure they drain away from your building’s crawlspace or basement.
    • Ensure the ground slopes away from all buildings on your property. Shoot for a downward slope of 5% for the first 10 feet. Check to see if pooling near your building foundation occurs after a heavy rain.
    • Direct downspouts away from your building’s foundation and make sure gutters are completely connected to them.
    • Install a 6-millimeter plastic vapor barrier on the floor of crawlspaces to reduce the amount of moisture evaporating from the ground and migrating inside your building.
    • Check your building’s crawlspace or basement for signs of water collection. Use your nose as well as your eyes to detect moisture: a dry, dusty smell is good; a damp, musty smell may indicate excessive moisture levels.

    Be diligent about routine maintenance. Small steps can prevent big problems.

    • Regularly inspect your building’s plumbing fixtures and roof for water leaks. Fix leaks immediately and take care to completely dry the surrounding area.
    • If units have air conditioners or dehumidifiers, empty the drip pans and make sure the drain lines are flowing properly.
    • Make sure heaters in units work properly. As long as air is circulating adequately, keeping indoor temperatures at around 68° will help inhibit mold growth.
    • Insulate cold-water pipes if you see condensation collecting on them.

    Act aggressively if you suspect mold is present.

    Mold consultants can contain and treat this spreading mold problem.

    • Don’t delay in addressing mold issues. The longer mold grows, the more damage it does.
    • If you observe mold, consider consulting a specialist to positively identify and remediate it.
    • If you can smell mold but can’t see the source, consult a specialist to help investigate. The mold could be hiding behind drywall, above ceiling tiles or under carpets. Uncovering hidden mold may disturb and release mold spores.
    • Do not run your building’s forced-air heating system if you think it may be contaminated with mold; doing this could spread mold spores throughout the building.

    More Mold and Moisture resources.

    Check your fan’s draw power

    Put a piece of toilet paper next to a running fan. If it doesn’t stick to the fan, the fan is likely not reducing moisture in the air.

    Access easy-to-follow mold prevention tips from the EPA

    The Environmental Protection Agency’s handy guide, Mold, Moisture, and Your Home, gives advice for residents and property managers on routine maintenance and indoor humidity control.

    Resident Communication and Education

    Advise residents to keep their apartments ventilated and dry. Provide a written notice with the following reminders:

    1) Keep your apartment ventilated:

    • Always run your bathroom vent fan when showering or bathing, and let it run for 15 additional minutes to vent away excess moisture. (Open your bathroom window if fans are not provided.)
    • Run the fan above your stove, or open your kitchen windows, while cooking and for 15 minutes after you’re done.
    • Crack or fully open your windows and/or doors for a half-hour every morning and evening. Remember to also open window curtains and blinds.
    • Keeping furniture and other belongings at least three inches away from walls will help prevent mold like this from growing.

    • Move furniture, mattresses, boxes and other belongings at least three inches away from walls. Make especially sure to move items away from exterior walls, where condensation is most likely to form.
    • Leave closet doors open and refrain from overfilling them.
    • Avoid clutter.
    • Consider purchasing a dehumidifier if mold or excess humidity persists.

    2) Keep your apartment dry:

    • Immediately report all plumbing leaks and moisture problems to your property manager.
    • Clean up water leaks, spills and condensation right away to prevent mold from growing.
    • Cover pots and pans when cooking.
    • Don’t hang wet clothes inside. Keep wet shoes outside.

    3) Follow these additional tips:

    • Tell your landlord if you have mold.
    • Clean more frequently, if necessary, to prevent mold from growing.
    • Don’t use a humidifier if your apartment is prone to mold.
    • If your apartment has a patch of mold smaller than 3 feet by 3 feet, clean the area with a solution of one cup vinegar and one cup water. Wear dishwashing gloves, unvented goggles and a N95 respirator (all available at a hardware store for under $20). Thoroughly scrub and dry the area.
    • Do not attempt to clean mold if the patch is larger than 3 feet by 3 feet; notify your landlord instead.
    • Pair warm air with good air circulation to prevent mold growth. Assuming your apartment is well ventilated, maintain an indoor temperature of 68°.

    More Mold and Moisture resources.

    Point your residents to Multnomah County’s healthy home resources.

    Written for tenants and landlords, What Makes a Healthy Home? contains tips on keeping apartments dry and ventilated.

    Rent Right: A Guide for Landlords and Tenants, developed by the Multnomah County Healthy Homes Coalition, discusses the different responsibilities that landlords and tenants have in making sure that rental units are safe, clean and habitable. It include helpful tips on mold prevention.

    Get the word out to non-English-speaking residents

    Provide translations of notices and signs in residents’ own languages. Consider using pictures and icons to communicate across multiple languages. Or ask bilingual residents, including youth, to verbally pass along the information to others in their language community.

    Cleaning up mold? Have the right equipment handy.

    Protect yourself with dishwashing gloves, unvented goggles and a N95 respirator.

    Design and Construction

    Keep rain and irrigation water flowing away from your building.

    • Direct downspouts away from the foundation. Grading should have a 5% slope away from the building for the first 10 feet.
    • Shape landscaping berms properly so that they carry water away from the building, rather than toward it.
    • Locate sprinklers at least one foot away from buildings to prevent intrusion of irrigation water.

    Provide suitable and sufficient mechanical ventilation systems.

    • Consider installing whole-house ventilation fans in each apartment. Whole-house fans provide 24-hour ventilation throughout an entire unit.
    • Also consider installing passive vents in each unit, a cost-effective way of drawing in fresh air and circulating it throughout the apartment.
    • Install occupancy-sensor fans in bathrooms; they automatically turn on when the room is occupied, and they stay on for a few minutes after it is vacated.
    • Vent fan ducts to the outside.

    Warm up your walls and windows.

    • Add insulation to your building’s exterior walls. Insulation causes the surface temperature of walls to increase, which reduces moisture condensation.
    • Install temporary (plastic) storm windows or new double-pane windows. This will increase the surface temperature of interior glass panes, which will in turn reduce interior moisture condensation.

    If attempting a major renovation, design your building envelope to the highest standards.

    • Ensure there is adequate air sealing/weatherization.
    • Ensure that window flashing is installed properly so that water drains to the outside.
    • Opt for roofs that have overhangs or eaves to keep rainwater away from siding.
    • If your building has a crawlspace, make sure it’s vented and a vapor barrier is installed.
    • Specify operable windows so that residents are better able to control the air circulation in their units.

    More Mold and Moisture resources.

    Get help paying for insulation and windows

    EnergyTrust of Oregon offers cash incentives for installing replacement windows and adding insulation to your attic, walls and underfloors. (Adequate insulation and tight-fitting, energy-efficient windows warm up interior surfaces, which reduces interior moisture condensation.)

    Consult the experts on improving your building envelope

    Oregon Housing and Community Services’ Building Enclosure Rehabilitation Guide: Multiunit Residential Wood-Framed Buildings focuses on how to manage heat, air and moisture transfer through building envelope design. It also offers guidance on assessing and rehabilitating wood-framed multifamily properties.

Rethink This Property

Rethink This Property

Mold and Moisture Control

Health-related design solutions for real East Portland apartment complexes.

We asked a team of architects to recommend health-related design solutions for real East Portland apartment complexes. These drawings illustrate how adding transom windows can improve interior airflow for better moisture control.

Get ideas for encouraging air movement in unit interiors. View the Improving Ventilation slideshow.

Images by Constructive Form Architecture & Design