How to Inspect & Repair Mobile Home or Trailer Roofs
InspectAPedia® -
Mobile home roof inspection guide
Lists of roofing defects found on mobile homes, trailers, double-wides
Guide to Roof, Wind, Foundation, Strutural & General Safety and building codes for mobile homes
Questions & answers about mobile home and trailer roof leaks, damage, diagnosis, & repair methods
How to Inspect the Roofs of Mobile Homes or Manufactured Housing for Defects: detailed procedures, defect lists, references to standards.
InspectAPedia offers impartial, unbiased advice without conflicts of interest.
We will block advertisements which we discover or readers inform us are associated with bad business practices,
false-advertising, or junk science. Our contact info is at
InspectAPedia.com/Contact.htm.
Ver.3.4 - 04/25/07, 08/21/2011 - Steve Vermilye, New Paltz NY and Daniel Friedman, Poughkeepsie NY,
Hudson Valley ASHI Chapter Seminar, Newburgh NY, January 4, 2000, NY Metro ASHI Fall 99 Seminar, Holiday Inn Crowne Plaza, White Plains NY, October
2, 1999. Our photo at page top shows inspector Steve Vermilye on a double-wide trailer roof shows areas of ponding and a history of tar patching - Ulster County New York.
Guide to Trailer & Mobile Home ROOFING DEFECTS - Inspecting for Mobile Home Roofing Defects
Low slope mobile home roofs (above left) are at risk of leaks in part because of their slower drainage rate and due to sagging with age. Our photo at above right shows a leak-prone low-slope roof on the mobile home in the foreground. Behind this home you can see that a steeper gabled roof has been added on that home - a roof less likely to be a source of chronic leaks.
Our photo below shows tar spills on the side of a mobile home whose roof was coated in attempts to stop leaking.
31% of mobile homes had roof problems; (C. R. survey)
Flat or near-flat roofs, may be covered with conventional shingles (slope too low)
Chimneys or plumbing vents "patched-over" so as to be blocked, and are frequently missing caps, a functional problem for the heater and a potential fire hazard.
Dents and ponding on mobile home roofs, and leaks at seams (patching with roof cement fixes leaks but corrodes metal)
Mobile home roofs with no overhang (common design) contribute to frequent leaks in walls at windows or wall tops;
Shingled roofs on mobile homes usually have overhang (added?); flat roofs don't. Metal roof seams leak;
Definitions: What is a Mobile Home, Trailer, Doublewide, Modular Home, Factory-Built Home, Panelized-Construction-Built Home?
The following is the opinion of the author and has not had a technical review by other industry experts.
Various trailer, mobile home, and modular housing
manufacturers may disagree with some of these views. Corrections and content suggestions are welcome.
Characteristics of Trailers as Living Space
Trailer traditionally describes a usually small, wheeled, home with a history and image of flimsy construction
such as wooden 1x3 wall framing clad with aluminum siding, virtually no insulation, and low quality leaky windows.
"Trailers" up until the 1970's (my estimate) included both campers which really were intended to be towed
by a car or truck and moved often from site to site (though some were left parked for decades at campgrounds),
and also lightweight factory-made homes which were intended to be towed once to a home site and then
kept there.
Our photo (left) shows a trailer that was finally abandoned as a living space. The little blue structure used as an addition to the left of the small house in the photo
at the top of this page was undoubtedly a small camper.
No one building "trailers" calls them that any longer because of the "flimsy" image. The closest thing to a "trailer" in
current products on the market are motor homes and campers.
The least-costly campers (such as our pickup truck "slide-on camper") built after 2000 are probably
considerably better constructed than the "trailers" of old.
In current language (2009), a "trailer" is either a "mobile home" that is more than 20 years old (see below),
or it is a camper designed to be moved easily and often from site to site.
(Or in different usage, a "utility trailer" is a utility vehicle intended to haul goods or large
items and designed to be fastened to the back of a car or truck, and a "tractor trailer" is of course
a larger (typically 40 ft long) hauling system for moving goods by highway from city to city.)
Trailers may have had their wheels left on, but normally they'd be set on a masonry pier foundation and a skirt installed
around to hide the under-trailer area.
Characteristics of Mobile Homes as Living Space
In the past few decades (to 2006), "trailer" manufacturers have considerably improved the quality of construction of
such homes. The national manufacturing and building code standards for these structures have also been improved.
Perhaps in part to escape the less than wholesome image of "trailer", manufacturers use the term "mobile home" to
describe what is usually larger and better made home than "trailers" of old, though perhaps with similar materials.
Mobile homes are built in a factory and are designed to be moved (once and uncommonly, perhaps once again)
on its own wheels attached to its own frame to a site where a foundation is prepared and connections to utilities are made.
In the U.S., states have regulations about the siting, foundation, steps and entry, wiring, plumbing,
tie-downs for wind and storm safety that apply to these homes.
Some examples of mobile
home regulations for New York State are this website.
Individual state regulations will vary - you'll want to see what your state requires.
Even within states regulations vary as wind and weather conditions do also.
Examples of mobile home improvements include stronger overall wall and roof construction,
less leaky roof covering, and windows that are less notoriously leaky. In addition
newer mobile homes have, for fire safety, bedroom windows that can be pushed out to a wide opening for
emergency exit in case of fire - an important safety improvement. Usually building departments grandfather in
older structures, but sometimes they will insist that certain life-safety improvements be made, for example
if an older mobile home is being brought to a new site in a new community. If this is the
case one or two windows may need to be replaced to provide this important safety improvement.
When there is a severe storm or hurricane, mobile home communities are among the worst damaged as a strong
wind can completely turn over or demolish mobile homes. For this reason, mobile homes set up in high wind-risk
zones have extra requirements for tie-downs to secure the building against upset during a storm.
Mobile homes may arrive on wheels but they will be jacked enough to be set on some type of approved
building foundation, such as masonry piers or a masonry foundation.
In case these terms are not confusing enough, some mobile home makers
like to call these "factory built homes". But that use of "factory-built homes"
is confusing too since modular homes are also "factory built" but are quite different from trailers or mobile homes.
Characteristics of a "Doublewide" Mobile Home or Trailer
Some manufacturers provide mobile homes constructed to be joined together, side by side to form a double-width
living unit. While a double-wide mobile home is basically constructed by the same materials and methods
just described above, the tie-down and connection requirements for these living units may be different
in some jurisdictions, since their risk of being blown away in high winds is different. Other installation
and support requirements, such as connection of the two units and placement of foundation support will also
have to accommodate this variation.
Characteristics of Modular Homes or Modular Housing
Modular homes, too, enjoyed a less than stellar reputation several decades ago, having the reputation of
flimsy construction. That is certainly no longer the case.
A modular home is constructed in a factory of one or more sections which are carried to the building site on
a trailer and lifted by a crane to be set upon a foundation which has been prepared ahead of time.
Modular homes
can be quite large, involving four or quite a few more individual sections which are lifted and "set" into place
at the site. Some manufacturers provide custom architectural services and can deliver unique, but factory-built
homes in sections.
Contemporary modular construction of homes have these attributes:
The home is built indoors in a factory under controlled conditions, usually resulting in straight and square
construction of walls, ceilings, roofs, and floors.
Exterior wall sheathing and roof sheathing are glued as well as nailed to the surfaces of their
respective studs or rafters. Interior sub flooring and drywall on walls and ceilings are also
glued as well as nailed or screwed to their joists or studs. Some models by some manufacturers also install
a double layer of interior drywall. These methods result in a very stiff and strong construction.
The home is probably built to meet the building code requirements of all U.S. states, or at least all of the
states within a manufacturer's shipping area. You'll find an identifying label for the home with this information,
often on a kitchen sink cabinet wall.
The home is built strong enough to be lifted at the factory by crane for setting atop a steel trailer for
transport, then driven at 65 MPH down a highway, pushed or dragged on its trailer over an often hilly and rough
construction site, and lifted again by crane for final "set" atop its foundation. Without falling apart. (Try this with a
stick-built house.) At the Contempri factory in Pennsylvania on a modular home construction tour about a decade
ago, suddenly all of the workers and managers dropped their tools, ran to their cars, and drove madly out of
the factory parking lot.
We followed to see what was happening. One of their modular sections was being towed
on U.S. interstate I84 when the trailer disconnected from the towing tractor. The tractor drove ahead. The trailer
ran off the highway at 65 MPH. The trailer ran head on into the end of a steel guard rail. The trailer stopped.
The modular home section kept going, and impaled itself centered atop the guard rail. When we got to the accident,
there was no debris anywhere except where the guardrail had punched out of the rear wall of the modular home section.
You could look in windows into the kitchen where the cabinets and appliances were perfectly in place.
When the modular home is transported to its site, it is moved by being lifted and set onto an independent
steel frame which has its own independent wheels. At the destination the modular home or home section is
lifted by crane and set onto an independent foundation, and the steel frame/wheel set returns to the factory
for re-use.
A modular home is normally set on a foundation which has already been placed at the building site.
If the modular home is placed over a basement or if there is to be an attached or detached garage, often that construction
is performed by a local building contractor rather than by the modular home manufacturer (sometimes resulting
in different quality of workmanship).
A modular home can be difficult to recognize once its construction has been completed. However these clues will
work every time:
In the basement, if the ceiling is not fully enclosed, look at the main girder. Since most modular homes use at least
two long sections that have to be built and transported to the site, there will be at least two completely independent
floor framing systems, and at their mating point over the basement center, you'll see an unusually wide built-up
girder with (if properly installed) through bolts connecting the two building sections.
In the living area, if the building is a two-story unit, as you walk up the stairs from first to second
level, notice that there are a few more steps than usual between floors? Since each of the four stacked sections in
a four-section two-story modular home has been framed with a complete floor, wall, and ceiling structure, the "ceiling"
between the first and second floors will be double the normal depth since it is comprised of both the first floor
section ceiling framing and the second floor section floor framing. So if 2x10 joists were used, there will be
about 20" of ceiling thickness between floor (a great place to run wires and ducts).
In the attic is the fail-safe way to always identify a modular-built home unless there is simply no attic access
or all surfaces are covered. You'll find one, possibly two or even three features unique to modular home construction:
(1) there will
be a mating joint of the front and rear sections of the home visible as two girders in the attic floor, running along
the long dimension of the building, usually with a small gap between them, hopefully with insulation or other fire blocking
stuffed into the gap. The reason for the gap is that properly placed, the sections are set with their bottom girders
touching tightly, which may leave the top sections slightly separated at their highest point.
(2) there may be hinged roof rafters. Many modular homes have roof slopes which would be much too high
for the upper roof-bearing sections to travel up the highway. They travel with the roof laid flat atop
the upper floor module. The roof rafters are hinged, roughly 18-24" from the eaves of the home, and are lifted
up at the site, then supported by an attic knee wall. So you'll see two knee walls, one supporting the front
and one the back roof section. You may see the hinges on the rafters down near the eaves as well.
(3) One modular home
we inspected had fallen off of its trailer while being lifted by the crane. It rolled over on its face. Like the
unit which had impaled itself on the guard rail, there was little damage other than broken windows. But there was
a slight crease in all of the roof shingles about 24" up from the eaves. The rafter hinges had all been slightly
bent when the section toppled. Outside, even on a modular section which has not fallen, you may see this telltale
line of slight shingle anomaly, parallel to the eaves.
Questions & Answers regarding this article
Questions & answers about mobile home and trailer roof leaks, damage, diagnosis, & repair methods
Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
Additional technical contributors & reference sources for this article are listed below.
Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
"Modular Home Construction, special defects and inspection methods" Dan Friedman, NY Metro ASHI Seminar, Holiday Inn, Crowne Plaza, White Plains NY, October 4, 1996
"Modular Home Construction, special defects and inspection methods" Dan Friedman, NY Metro ASHI Seminar, Holiday Inn, Crowne Plaza, White Plains NY, October 4, 1996
New York State: "Manufactured Homes: an installation guide for the code enforcement official," undated. [Div. of Code Enforcement & Admin. - 518-474-4073, George E. Clark, Jr., Director] - this is a guide tool, not an enforcement code or standard.
HUD State Administrative Agency (for 36 states) (NY: 518-474-4073) - for complaints
Manufactured Housing Institute, 2101 Wilson Blvd. Ste. 610, Arlington VA 22201 703-558-0400 www.mfghome.org
NYMHA, 35 Commerce Ave., Albany NY 12206-2015 518-435-9859 800-721-HOME (they want the Star Program to provide for separate assessment of manufactured homes)
Consumer Reports: www.consumerreports.org - special report 2/98
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop. The Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ® editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
Design of Wood Structures - ASD, Donald E. Breyer, Kenneth Fridley, Kelly Cobeen, David Pollock, McGraw Hill, 2003, ISBN-10: 0071379320, ISBN-13: 978-0071379328
This book is an update of a long-established text dating from at least 1988 (DJF); Quoting: This book is gives a good grasp of seismic design for wood structures. Many of the examples especially near the end are good practice for the California PE Special Seismic Exam design questions. It gives a good grasp of how seismic forces move through a building and how to calculate those forces at various locations.THE CLASSIC TEXT ON WOOD DESIGN UPDATED TO INCLUDE THE LATEST CODES AND DATA. Reflects the most recent provisions of the 2003 International Building Code and 2001 National Design Specification for Wood Construction. Continuing the sterling standard set by earlier editions, this indispensable reference clearly explains the best wood design techniques for the safe handling of gravity and lateral loads. Carefully revised and updated to include the new 2003 International Building Code, ASCE 7-02 Minimum Design Loads for Buildings and Other Structures, the 2001 National Design Specification for Wood Construction, and the most recent Allowable Stress Design.
Diagnosing & Repairing House Structure Problems, Edgar O. Seaquist, McGraw Hill, 1980 ISBN 0-07-056013-7 (obsolete, incomplete, missing most diagnosis steps, but very good reading; out of print but used copies are available at Amazon.com, and reprints are available from some inspection tool suppliers). Ed Seaquist was among the first speakers invited to a series of educational conferences organized by D Friedman for ASHI, the American Society of Home Inspectors, where the topic of inspecting the in-service condition of building structures was first addressed.
Defects and Deterioration in Buildings: A Practical Guide to the Science and Technology of Material Failure, Barry Richardson, Spon Press; 2d Ed (2001), ISBN-10: 041925210X, ISBN-13: 978-0419252108. Quoting: A professional reference designed to assist surveyors, engineers, architects and contractors in diagnosing existing problems and avoiding them in new buildings. Fully revised and updated, this edition, in new clearer format, covers developments in building defects, and problems such as sick building syndrome. Well liked for its mixture of theory and practice the new edition will complement Hinks and Cook's student textbook on defects at the practitioner level.
"Avoiding Foundation Failures," Robert Marshall, Journal of Light Construction, July, 1996 (Highly recommend this article-DF)
"A Foundation for Unstable Soils," Harris Hyman, P.E., Journal of Light Construction, May 1995
"Backfilling Basics," Buck Bartley, Journal of Light Construction, October 1994
"Inspecting Block Foundations," Donald V. Cohen, P.E., ASHI Reporter, December 1998. This article in turn cites the Fine Homebuilding article noted below.
"When Block Foundations go Bad," Fine Homebuilding, June/July 1998
Masonry structures: The Masonry House, Home Inspection of a Masonry Building & Systems, Stephen Showalter (director, actor), DVD, Quoting: Movie Guide Experienced home inspectors and new home inspectors alike are sure to learn invaluable tips in this release designed to take viewers step-by-step through the home inspection process. In addition to being the former president of the National Association of Home Inspectors (NAHI), a longstanding member of the NAHI, the American Society of Home Inspectors (ASHI), and the Environmental Standard Organization (IESO), host Stephen Showalter has performed over 8000 building inspections - including environmental assessments. Now, the founder of a national home inspection school and inspection training curriculum shares his extensive experience in the inspection industry with everyday viewers looking to learn more about the process of evaluating homes. Topics covered in this release include: evaluation of masonry walls; detection of spalling from rebar failure; inspection of air conditioning systems; grounds and landscaping; electric systems and panel; plumbing supply and distribution; plumbing fixtures; electric furnaces; appliances; evaluation of electric water heaters; and safety techniques. Jason Buchanan --Jason Buchanan, All Movie Review
Masonry Structures: Behavior and Design, Robert G. Drysdale, Ahmid A. Hamid, Lawrie R. Baker, The Masonry Society; 2nd edition (1999), ISBN-10: 1929081014, ISBN-13: 978-1929081011
Straw Bale Home Design, U.S. Department of Energy provides information on strawbale home construction - original source at http://www.energysavers.gov/your_home/designing_remodeling/index.cfm/mytopic=10350
More Straw Bale Building: A Complete Guide to Designing and Building with Straw (Mother Earth News Wiser Living Series), Chris Magwood, Peter Mack, New Society Publishers (February 1, 2005), ISBN-10: 0865715181 ISBN-13: 978-0865715189 - Quoting: Straw bale houses are easy to build, affordable, super energy efficient, environmentally friendly, attractive, and can be designed to match the builder’s personal space needs, esthetics and budget. Despite mushrooming interest in the technique, however, most straw bale books focus on “selling” the dream of straw bale building, but don’t adequately address the most critical issues faced by bale house builders. Moreover, since many developments in this field are recent, few books are completely up to date with the latest techniques. More Straw Bale Building is designed to fill this gap. A completely rewritten edition of the 20,000-copy best--selling original, it leads the potential builder through the entire process of building a bale structure, tackling all the practical issues: finding and choosing bales; developing sound building plans; roofing; electrical, plumbing, and heating systems; building code compliance; and special concerns for builders in northern climates.
Mobile View
InspectAPedia ® Home & Site Map
