HomeOwners for Better Building - Mold and New Home Construction Guide

Bulk Water --
Improper lot grading and/or settling create slopes toward foundations and allow
water to intrude into slabs, crawlspaces or basements; irrigation systems
overspray water and repeatedly wet foundations and walls; and roof downspouts
are inadequately separated away from homes and deposit water near
foundations instead of to a properly sloped grade.

Roof Eaves --
Roof eaves lack sufficient extensions outward and permit rain, especially wind
driven rain, to soak exterior porous (brick, stucco, wood, etc.) facades.

Vapor Barriers --
Barriers are sometimes incorrectly applied or of the wrong type, depending on
climate, and allow moisture to be trapped or build up in walls. Walls need to be
able to breathe.

Window Detailing in Wall and Roof Penetrations --
o Builders and subcontractors lack sufficient training for proper installation of
windows (and flashing).
o Building codes lack standardized window installation practices.
o Standards are non-existent for installation of building membranes and
flashings with windows.
o Standards for windows, building membranes, and flashing are outdated
(post WW-II ASTM standards) and need to be modernized.
o Trade organizations for fenestration, building membranes, and flashing
are needed to foster these training, standard, and code activities.• Interior Moisture/HVAC --
o Houses are too tight for natural ventilation to be effective. Mechanical
outside air (OA) ventilation is needed.
o Architects and engineers need to be educated on ventilation issues and
mechanical ventilation options.
o Oriented Strand Board (OSB) is often gets wet during construction and
then is not adequately dried before wall and roof construction is
completed.
o Some newer paints have much less tolerance to mold growth than paints
manufactured 20-25 years ago.
o DHW heaters, AC coils/drain pans, and ductwork, are placed in attics
where leaks can go unnoticed for some time until after substantial damage
is done.
o Baths and kitchens do not have properly sized exhaust fans that run until
moisture levels are reduced to desired humidity levels. Fan operation
needs to be automated (based on humidity level) to remove the human
factor. Most of these fans are too noisy and people are annoyed and limit
their operation.
o Wet spray cellulose, if used, Is not allowed to dry sufficiently. Moisture
content needs to be checked before closing drywall.
o Moisture content in wood framing is often to high before closing in the
walls. Moisture content needs to be checked before closing drywall and
should not be higher than 19%.

Miscellaneous
o An homeowners’ manual needs to be developed that would address some
of the maintenance issues that could prevent mold incidences over the life
of a house.
o A builders’ manual needs to be developed that offers a "systems
approach" to ensuring quality and managing risk during construction. For
example, utilizing a series of checkpoints established by extensive
litigation and failure analysis background, specially trained inspectors can
check for specific, known anomalies in the building assemblies at greatest
risk of water damage and mold formation.
o Construction sequencing is a clear issue with poor scheduling leading to
unprotected building materials getting soaked with rain/snow on the job
site.
o Elastomeric paints for stucco to limit cracking and water intrusion need to
be utilized.

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