Solving Moisture Problems in Manufactured Homes
Moisture, as liquid and vapor, is an integral
part of daily life. We breathe it, drink it, bathe in it, and use
it for growing foods. We don't often think of it as being the cause
of a potentially serious problem in housing.
Most building materials can tolerate occasional wetting-as long
as they also have sufficient exposure to air, which allows moisture
to dry out. At times, however, circumstances prevent drying and
cause moisture to build up to amounts that can damage a home. When
damage does occur, it can be difficult to diagnose and expensive
to repair. Extreme moisture problems can degrade the building material's
strength and insulation capacity; support mold and rust growth;
and increase the weight of building materials beyond the capacity
of supporting structures.
Moisture-related problems are relatively rare, but are occurring
with greater frequency in new homes, particularly in the hot, humid
areas of the nation. Moisture problems, however, can occur in all
climates and regions.
The best approach for avoiding moisture-related problems is to take
preventative steps that keep excessive moisture buildup from occurring.
These steps can be found in Moisture Problems in Manufactured Homes:
Understanding Their Causes and Finding Solutions, the Manufactured
Housing Research Alliance's most recent addition to its Excellence
in Design, Manufacturing, and Installation Series. This user-friendly
guide is designed to assist manufacturers, retailers, setup crews,
and homeowners in recognizing and solving moisture problems in manufactured
|Ice dams occur when attic insulation is
insufficient or warm home air enters the attic space. Melting
snow or ice on the roof surface backs up and seeps through
the shingles into the roof, damaging materials and reducing
This heavily illustrated guide covers steps
that can be taken to prevent moisture problems from occurring,
curing problems that do occur and understanding the building science
of moisture flow and accumulation. Easy-to-use checklists are
included to help recognize proven strategies for preventing moisture
problems. Practical examples and case studies illustrate symptoms,
causes and remedies of specific moisture problems.
The wall can store some moisture as long as it can dry out.
Moisture is added faster than it can dry out and damage occurs.
Decisions are made at every stage in the life
cycle of the home that influence whether or not the home will experience
moisture problems: in home design and construction; during set up;
and in the way the home is operated. The MHRA moisture guide makes
clear that the decisions and actions of the manufacturer, installer
and homeowner all play key roles in assuring that moisture does
not accumulate on building surfaces and within building components
causing discoloring, damage and possibly building system failures.
Avoiding Problems Through Design and Construction
|A properly graded site has a crown underneath
the home and sloping ground that carries water away from the
house, unlike the poor grading job shown below
Moisture Problems in Manufactured Homes: Understanding
Their Causes and Finding Solutions suggests how and why manufacturers
are the first line of defense against moisture problems. With loads
of case studies and illustrated examples, manufacturers are shown
how to take into consideration the most important factors that will
impact the tendency of moisture to accumulate and cause future problems,
and the role of the manufacturer in helping the installer and homeowner
recognize their contribution to minimizing such problems.
By taking a few extra precautions during the design and home production
stage, manufacturers can significantly reduce moisture risk, at
little added cost.
|When the vapor retarder is on the interior
wall in hot, humid climates, warm, moist air that enters the
wall cavity can accumulate on the cold interior wall board,
causing it to swell and disintegrate.
Avoiding Problems Through Setup
The guide clearly documents and demonstrates
that even the best design for moisture control can be compromised
by common errors made in home installation. Although manufactured
homes are primarily built in a factory, on-site installation crews
handle critical tasks that will impact the home's future moisture
The quality of the setup can contribute to home comfort, durability,
and efficiency or result in discomfort, high-energy costs, and moisture
problems. The installation can easily tip the scales in either direction.
Setup is a difficult task. It is dirty, dangerous, and demanding.
Completion deadlines often require intimate knowledge of several
manufacturers' installation instructions; work in confined spaces;
and a knack for simultaneously satisfying manufacturers, retailers,
state inspectors, and homeowners. Just as in manufacture, a poor
installation can defeat even the best planning. Given the financial
pressures of completing the setup quickly, it can be tempting for
a setup crew to take shortcuts that have a negative effect on the
Among the steps the set-up crew can take to avoid moisture problems
described in the guide are the following: properly grading the site
to shed water, installing a ground cover, properly sealing the marriage
line, attaching the cross over duct securely and with a permanent
connector, and properly sizing cooling equipment.
|Warping of the floor sheathing can occur
when a hole in the bottom board allows moist crawlspace air
to condense on exposed metal ducts. Water is absorbed by the
floor sheathing, causing it to swell.
Avoiding Problems Through Operation
Homeowners who are usually the first to experience any symptoms of
moisture problems will find this guide enlightening, particularly
if they assume that they have no role in avoiding moisture damage.
The guide teaches homeowners how to avoid moisture problems by proper
care and operation of their home. It also helps homeowners recognize
problem symptoms so they can be addressed quickly, correcting small
problems before they become big ones. This is especially important
for people with allergies or asthma, conditions that might be exacerbated
by mold and mildew brought on by moisture buildup.
The guide delves into actual case study examples of homes that have
experienced moisture-related damage and the actions taken to remedy
the damage. It also describes the basic building blocks of moisture
dynamics: moisture source, movement, and accumulation.