Look out for these construction and moisture management defects to succeed in buying or renting a healthy, mold free home.
1. Inspect the roof design with an eye towards drainage. Water follows gravity.
Do valleys come together creating an area that will store water rather than drain it away?
Does a roof slope send water towards an adjacent wall?
These types of poor design details will fail and result in water accumulation and leaks over time.
2. Check drainage around the outside of the structure. Water flows downhill. Water should never be allowed to flow toward a structure. Notice neighbors - is their property draining toward yours?
Grade slope away from foundations should be a minimum of 6" in 10ft. In new construction the slope away should be even more as ground adjacent to the foundation has been disturbed and will settle over the next 10 years. What was once a slope away could turn into an avenue for water to enter the foundation over time.
3. Gutters and downspouts with long extensions away from the structure are an essential component of moisture management.
4. There should be a minimum of 6" of clearance from the ground to the start of floor framing or exterior wall finishes. I suggest 8". This often means an partially-exposed foundation wall.
5. Look for roof overhangs - the larger, the better. Your roof acts an umbrella over your structure. Shallow or non-existent overhangs are known to be associated with high incidence of water damage in outside walls.
6. Only use solid sheet metal ductwork. Remember that homes with flex duct throughout can never be effectively cleaned. Ducts collect dust in the air, which can be a food source for mold. They should be cleaned, on average, about every 8-10 years, depending on circumstances.
7. Any new house should have clean ductwork. Ask to remove some registers and check yourself with a Swiffer cloth. Ask to see the filter. Walk away if a new house has debris in ductwork. Debris in ductwork on new construction is a sign of very careless work and negligent oversight. Silica from drywall dust is also highly toxic.
Drywall work should never be done with the HVAC system running which will bring that dust into the system. Silica dust from drywall work is very difficult, if not impossible to remove, as the dust is very fine. If precautions were not taken to prevent the HVAC from being contaminated during the construction process, there's likely to be many other defects, oversights, poor construction and deficits due to lack of attention to detail, that are much harder to find easily. Consider debris in ductwork a red flag and walk away. If builders realize that people are noticing, they may start taking precautions.
8. Avoid HVAC systems in unconditioned spaces such as attics, garages and crawl spaces. Ductwork should be in the conditioned space as well. If ductwork must go into an attic or crawlspace it must be very well sealed and insulated.
9. Check for bathroom exhaust fans. Never buy a home without them. (Unless you will install one ASAP). Size exhaust fans correctly for the room and length of duct run. (Yes, there are calculations to do!) Insulated ducts to exterior. Install timer switches to ensure bath exhaust fans are used for at least 30 minutes after bathing or showering.
10. Check routing of all exhaust fan outlets, including bathroom fans, dryers, and kitchen exhausts. Solid duct is best, with few elbows and only short, direct runs to a wall or roof. Do NOT put exhaust outlets next to air intake vents!!! (I can't believe I had to write that...but this common error is everywhere!) Warm moist air wants to rise and will be drawn into the attic space when exhaust outlets are located next to soffit vents. Expect mold to grow in these attics over time. See mold pictures HERE.
NEVER accept bathroom, kitchen or dryer exhaust fans dispelling air into the crawl space, basement, attic.
11. Ask to see the construction details for the foundation for new construction. Know that any foundation type can have a moisture problem including slab, crawl space and basement foundations.
Crawl spaces should never have exposed dirt floor. Any soil which is a part of enclosed living space, must be encapsulated with a vapor barrier with all seams sealed. Also the vapor barrier must be sealed to the crawl space walls. Make sure exposed vapor barriers in crawl spaces are protected to avoid holes and breeches to this important protection layer.
12. Fully evaluate all pros and cons of any chemicals, biocides or sealants and other building products that might be suggested for new construction or already installed in buildings. Be cautious of particle board as it often off-gasses formaldhyde. Be wary of cabinet materials, shelving and closet doors which are often made of particle board or other substrates which may off-gas formaldehyde. NOTE: Particle board is NOT OSB (Oriented Strand Board). These are different products. OSB is a structural material while Particle Board is not.